Annotation of src/usr.bin/ssh/authfd.c, Revision 1.25
1.1 deraadt 1: /*
1.18 markus 2: *
1.13 deraadt 3: * authfd.c
1.18 markus 4: *
1.13 deraadt 5: * Author: Tatu Ylonen <ylo@cs.hut.fi>
1.18 markus 6: *
1.13 deraadt 7: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8: * All rights reserved
1.18 markus 9: *
1.13 deraadt 10: * Created: Wed Mar 29 01:30:28 1995 ylo
1.18 markus 11: *
1.13 deraadt 12: * Functions for connecting the local authentication agent.
1.18 markus 13: *
1.25 ! markus 14: * SSH2 implementation,
! 15: * Copyright (c) 2000 Markus Friedl. All rights reserved.
! 16: *
1.13 deraadt 17: */
1.1 deraadt 18:
19: #include "includes.h"
1.25 ! markus 20: RCSID("$OpenBSD: authfd.c,v 1.24 2000/08/15 19:20:46 markus Exp $");
1.1 deraadt 21:
22: #include "ssh.h"
23: #include "rsa.h"
24: #include "buffer.h"
25: #include "bufaux.h"
26: #include "xmalloc.h"
27: #include "getput.h"
28:
1.17 markus 29: #include <openssl/rsa.h>
1.22 markus 30: #include <openssl/dsa.h>
31: #include <openssl/evp.h>
32: #include "key.h"
33: #include "authfd.h"
34: #include "kex.h"
1.25 ! markus 35: #include "dsa.h"
1.2 provos 36:
1.21 markus 37: /* helper */
1.24 markus 38: int decode_reply(int type);
1.21 markus 39:
1.1 deraadt 40: /* Returns the number of the authentication fd, or -1 if there is none. */
41:
1.2 provos 42: int
1.8 markus 43: ssh_get_authentication_socket()
1.1 deraadt 44: {
1.12 markus 45: const char *authsocket;
1.23 deraadt 46: int sock, len;
1.12 markus 47: struct sockaddr_un sunaddr;
48:
49: authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
50: if (!authsocket)
51: return -1;
52:
53: sunaddr.sun_family = AF_UNIX;
54: strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
1.23 deraadt 55: sunaddr.sun_len = len = SUN_LEN(&sunaddr)+1;
1.12 markus 56:
57: sock = socket(AF_UNIX, SOCK_STREAM, 0);
58: if (sock < 0)
59: return -1;
60:
61: /* close on exec */
62: if (fcntl(sock, F_SETFD, 1) == -1) {
63: close(sock);
64: return -1;
65: }
1.23 deraadt 66: if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) {
1.12 markus 67: close(sock);
68: return -1;
69: }
70: return sock;
1.1 deraadt 71: }
72:
1.24 markus 73: int
1.25 ! markus 74: ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
1.24 markus 75: {
76: int l, len;
77: char buf[1024];
78:
79: /* Get the length of the message, and format it in the buffer. */
80: len = buffer_len(request);
81: PUT_32BIT(buf, len);
82:
83: /* Send the length and then the packet to the agent. */
84: if (atomicio(write, auth->fd, buf, 4) != 4 ||
85: atomicio(write, auth->fd, buffer_ptr(request),
86: buffer_len(request)) != buffer_len(request)) {
87: error("Error writing to authentication socket.");
88: return 0;
89: }
90: /*
91: * Wait for response from the agent. First read the length of the
92: * response packet.
93: */
94: len = 4;
95: while (len > 0) {
96: l = read(auth->fd, buf + 4 - len, len);
97: if (l <= 0) {
98: error("Error reading response length from authentication socket.");
99: return 0;
100: }
101: len -= l;
102: }
103:
104: /* Extract the length, and check it for sanity. */
105: len = GET_32BIT(buf);
106: if (len > 256 * 1024)
107: fatal("Authentication response too long: %d", len);
108:
109: /* Read the rest of the response in to the buffer. */
110: buffer_clear(reply);
111: while (len > 0) {
112: l = len;
113: if (l > sizeof(buf))
114: l = sizeof(buf);
115: l = read(auth->fd, buf, l);
116: if (l <= 0) {
117: error("Error reading response from authentication socket.");
118: return 0;
119: }
120: buffer_append(reply, (char *) buf, l);
121: len -= l;
122: }
123: return 1;
124: }
125:
1.14 markus 126: /*
127: * Closes the agent socket if it should be closed (depends on how it was
128: * obtained). The argument must have been returned by
129: * ssh_get_authentication_socket().
130: */
1.1 deraadt 131:
1.18 markus 132: void
1.12 markus 133: ssh_close_authentication_socket(int sock)
1.1 deraadt 134: {
1.12 markus 135: if (getenv(SSH_AUTHSOCKET_ENV_NAME))
136: close(sock);
1.1 deraadt 137: }
138:
1.14 markus 139: /*
140: * Opens and connects a private socket for communication with the
141: * authentication agent. Returns the file descriptor (which must be
142: * shut down and closed by the caller when no longer needed).
143: * Returns NULL if an error occurred and the connection could not be
144: * opened.
145: */
1.1 deraadt 146:
1.12 markus 147: AuthenticationConnection *
148: ssh_get_authentication_connection()
1.1 deraadt 149: {
1.12 markus 150: AuthenticationConnection *auth;
151: int sock;
1.1 deraadt 152:
1.12 markus 153: sock = ssh_get_authentication_socket();
154:
1.14 markus 155: /*
156: * Fail if we couldn't obtain a connection. This happens if we
157: * exited due to a timeout.
158: */
1.12 markus 159: if (sock < 0)
160: return NULL;
161:
162: auth = xmalloc(sizeof(*auth));
163: auth->fd = sock;
164: buffer_init(&auth->identities);
165: auth->howmany = 0;
166:
167: return auth;
1.1 deraadt 168: }
169:
1.14 markus 170: /*
171: * Closes the connection to the authentication agent and frees any associated
172: * memory.
173: */
1.1 deraadt 174:
1.18 markus 175: void
1.25 ! markus 176: ssh_close_authentication_connection(AuthenticationConnection *auth)
1.1 deraadt 177: {
1.25 ! markus 178: buffer_free(&auth->identities);
! 179: close(auth->fd);
! 180: xfree(auth);
1.1 deraadt 181: }
182:
1.14 markus 183: /*
184: * Returns the first authentication identity held by the agent.
185: */
1.1 deraadt 186:
1.25 ! markus 187: Key *
! 188: ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
1.1 deraadt 189: {
1.25 ! markus 190: int type, code1 = 0, code2 = 0;
1.24 markus 191: Buffer request;
1.25 ! markus 192:
! 193: switch(version){
! 194: case 1:
! 195: code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
! 196: code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
! 197: break;
! 198: case 2:
! 199: code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
! 200: code2 = SSH2_AGENT_IDENTITIES_ANSWER;
! 201: break;
! 202: default:
! 203: return NULL;
! 204: }
1.1 deraadt 205:
1.14 markus 206: /*
207: * Send a message to the agent requesting for a list of the
208: * identities it can represent.
209: */
1.24 markus 210: buffer_init(&request);
1.25 ! markus 211: buffer_put_char(&request, code1);
1.12 markus 212:
213: buffer_clear(&auth->identities);
1.24 markus 214: if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
215: buffer_free(&request);
1.25 ! markus 216: return NULL;
1.12 markus 217: }
1.24 markus 218: buffer_free(&request);
1.1 deraadt 219:
1.12 markus 220: /* Get message type, and verify that we got a proper answer. */
1.24 markus 221: type = buffer_get_char(&auth->identities);
1.25 ! markus 222: if (type == SSH_AGENT_FAILURE) {
! 223: return NULL;
! 224: } else if (type != code2) {
1.24 markus 225: fatal("Bad authentication reply message type: %d", type);
1.25 ! markus 226: }
1.12 markus 227:
228: /* Get the number of entries in the response and check it for sanity. */
229: auth->howmany = buffer_get_int(&auth->identities);
230: if (auth->howmany > 1024)
1.24 markus 231: fatal("Too many identities in authentication reply: %d\n",
232: auth->howmany);
1.12 markus 233:
234: /* Return the first entry (if any). */
1.25 ! markus 235: return ssh_get_next_identity(auth, comment, version);
1.1 deraadt 236: }
237:
1.25 ! markus 238: Key *
! 239: ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
1.1 deraadt 240: {
1.12 markus 241: unsigned int bits;
1.25 ! markus 242: unsigned char *blob;
! 243: unsigned int blen;
! 244: Key *key = NULL;
1.9 markus 245:
1.12 markus 246: /* Return failure if no more entries. */
247: if (auth->howmany <= 0)
1.25 ! markus 248: return NULL;
1.12 markus 249:
1.14 markus 250: /*
251: * Get the next entry from the packet. These will abort with a fatal
252: * error if the packet is too short or contains corrupt data.
253: */
1.25 ! markus 254: switch(version){
! 255: case 1:
! 256: key = key_new(KEY_RSA);
! 257: bits = buffer_get_int(&auth->identities);
! 258: buffer_get_bignum(&auth->identities, key->rsa->e);
! 259: buffer_get_bignum(&auth->identities, key->rsa->n);
! 260: *comment = buffer_get_string(&auth->identities, NULL);
! 261: if (bits != BN_num_bits(key->rsa->n))
! 262: log("Warning: identity keysize mismatch: actual %d, announced %u",
! 263: BN_num_bits(key->rsa->n), bits);
! 264: break;
! 265: case 2:
! 266: blob = buffer_get_string(&auth->identities, &blen);
! 267: *comment = buffer_get_string(&auth->identities, NULL);
! 268: key = dsa_key_from_blob(blob, blen);
! 269: xfree(blob);
! 270: break;
! 271: default:
! 272: return NULL;
! 273: break;
! 274: }
1.12 markus 275: /* Decrement the number of remaining entries. */
276: auth->howmany--;
1.25 ! markus 277: return key;
1.1 deraadt 278: }
279:
1.14 markus 280: /*
281: * Generates a random challenge, sends it to the agent, and waits for
282: * response from the agent. Returns true (non-zero) if the agent gave the
283: * correct answer, zero otherwise. Response type selects the style of
284: * response desired, with 0 corresponding to protocol version 1.0 (no longer
285: * supported) and 1 corresponding to protocol version 1.1.
286: */
1.1 deraadt 287:
1.2 provos 288: int
289: ssh_decrypt_challenge(AuthenticationConnection *auth,
1.25 ! markus 290: Key* key, BIGNUM *challenge,
1.24 markus 291: unsigned char session_id[16],
292: unsigned int response_type,
293: unsigned char response[16])
1.1 deraadt 294: {
1.12 markus 295: Buffer buffer;
1.24 markus 296: int success = 0;
297: int i;
298: int type;
1.12 markus 299:
1.25 ! markus 300: if (key->type != KEY_RSA)
! 301: return 0;
! 302: if (response_type == 0) {
! 303: log("Compatibility with ssh protocol version 1.0 no longer supported.");
! 304: return 0;
! 305: }
1.12 markus 306: buffer_init(&buffer);
1.24 markus 307: buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
1.25 ! markus 308: buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
! 309: buffer_put_bignum(&buffer, key->rsa->e);
! 310: buffer_put_bignum(&buffer, key->rsa->n);
1.12 markus 311: buffer_put_bignum(&buffer, challenge);
312: buffer_append(&buffer, (char *) session_id, 16);
313: buffer_put_int(&buffer, response_type);
314:
1.24 markus 315: if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
1.12 markus 316: buffer_free(&buffer);
317: return 0;
318: }
1.24 markus 319: type = buffer_get_char(&buffer);
1.12 markus 320:
1.24 markus 321: if (type == SSH_AGENT_FAILURE) {
1.12 markus 322: log("Agent admitted failure to authenticate using the key.");
1.24 markus 323: } else if (type != SSH_AGENT_RSA_RESPONSE) {
324: fatal("Bad authentication response: %d", type);
325: } else {
326: success = 1;
327: /*
328: * Get the response from the packet. This will abort with a
329: * fatal error if the packet is corrupt.
330: */
331: for (i = 0; i < 16; i++)
332: response[i] = buffer_get_char(&buffer);
1.12 markus 333: }
334: buffer_free(&buffer);
1.24 markus 335: return success;
1.12 markus 336: }
1.1 deraadt 337:
1.25 ! markus 338: /* ask agent to sign data, returns -1 on error, 0 on success */
! 339: int
! 340: ssh_agent_sign(AuthenticationConnection *auth,
! 341: Key *key,
! 342: unsigned char **sigp, int *lenp,
! 343: unsigned char *data, int datalen)
! 344: {
! 345: Buffer msg;
! 346: unsigned char *blob;
! 347: unsigned int blen;
! 348: int type;
! 349: int ret = -1;
! 350:
! 351: if (dsa_make_key_blob(key, &blob, &blen) == 0)
! 352: return -1;
! 353:
! 354: buffer_init(&msg);
! 355: buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
! 356: buffer_put_string(&msg, blob, blen);
! 357: buffer_put_string(&msg, data, datalen);
! 358: xfree(blob);
! 359:
! 360: if (ssh_request_reply(auth, &msg, &msg) == 0) {
! 361: buffer_free(&msg);
! 362: return -1;
! 363: }
! 364: type = buffer_get_char(&msg);
! 365: if (type == SSH_AGENT_FAILURE) {
! 366: log("Agent admitted failure to sign using the key.");
! 367: } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
! 368: fatal("Bad authentication response: %d", type);
! 369: } else {
! 370: ret = 0;
! 371: *sigp = buffer_get_string(&msg, lenp);
! 372: }
! 373: buffer_free(&msg);
! 374: return ret;
! 375: }
! 376:
1.22 markus 377: /* Encode key for a message to the agent. */
378:
379: void
380: ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment)
381: {
382: buffer_clear(b);
383: buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
384: buffer_put_int(b, BN_num_bits(key->n));
385: buffer_put_bignum(b, key->n);
386: buffer_put_bignum(b, key->e);
387: buffer_put_bignum(b, key->d);
388: /* To keep within the protocol: p < q for ssh. in SSL p > q */
389: buffer_put_bignum(b, key->iqmp); /* ssh key->u */
390: buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
391: buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
392: buffer_put_string(b, comment, strlen(comment));
393: }
394:
395: void
396: ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment)
397: {
398: buffer_clear(b);
399: buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
400: buffer_put_cstring(b, KEX_DSS);
401: buffer_put_bignum2(b, key->p);
402: buffer_put_bignum2(b, key->q);
403: buffer_put_bignum2(b, key->g);
404: buffer_put_bignum2(b, key->pub_key);
405: buffer_put_bignum2(b, key->priv_key);
406: buffer_put_string(b, comment, strlen(comment));
407: }
408:
1.14 markus 409: /*
410: * Adds an identity to the authentication server. This call is not meant to
411: * be used by normal applications.
412: */
1.1 deraadt 413:
1.18 markus 414: int
1.22 markus 415: ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
1.1 deraadt 416: {
1.25 ! markus 417: Buffer msg;
1.24 markus 418: int type;
1.12 markus 419:
1.25 ! markus 420: buffer_init(&msg);
1.22 markus 421:
422: switch (key->type) {
423: case KEY_RSA:
1.25 ! markus 424: ssh_encode_identity_rsa(&msg, key->rsa, comment);
1.22 markus 425: break;
426: case KEY_DSA:
1.25 ! markus 427: ssh_encode_identity_dsa(&msg, key->dsa, comment);
1.22 markus 428: break;
429: default:
1.25 ! markus 430: buffer_free(&msg);
1.22 markus 431: return 0;
432: break;
433: }
1.25 ! markus 434: if (ssh_request_reply(auth, &msg, &msg) == 0) {
! 435: buffer_free(&msg);
1.12 markus 436: return 0;
437: }
1.25 ! markus 438: type = buffer_get_char(&msg);
! 439: buffer_free(&msg);
1.24 markus 440: return decode_reply(type);
1.12 markus 441: }
1.1 deraadt 442:
1.14 markus 443: /*
444: * Removes an identity from the authentication server. This call is not
445: * meant to be used by normal applications.
446: */
1.1 deraadt 447:
1.18 markus 448: int
1.25 ! markus 449: ssh_remove_identity(AuthenticationConnection *auth, Key *key)
1.1 deraadt 450: {
1.25 ! markus 451: Buffer msg;
1.24 markus 452: int type;
1.25 ! markus 453: unsigned char *blob;
! 454: unsigned int blen;
1.12 markus 455:
1.25 ! markus 456: buffer_init(&msg);
1.12 markus 457:
1.25 ! markus 458: if (key->type == KEY_RSA) {
! 459: buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
! 460: buffer_put_int(&msg, BN_num_bits(key->rsa->n));
! 461: buffer_put_bignum(&msg, key->rsa->e);
! 462: buffer_put_bignum(&msg, key->rsa->n);
! 463: } else if (key->type == KEY_DSA) {
! 464: dsa_make_key_blob(key, &blob, &blen);
! 465: buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
! 466: buffer_put_string(&msg, blob, blen);
! 467: xfree(blob);
! 468: } else {
! 469: buffer_free(&msg);
! 470: return 0;
! 471: }
! 472: if (ssh_request_reply(auth, &msg, &msg) == 0) {
! 473: buffer_free(&msg);
1.12 markus 474: return 0;
475: }
1.25 ! markus 476: type = buffer_get_char(&msg);
! 477: buffer_free(&msg);
1.24 markus 478: return decode_reply(type);
1.12 markus 479: }
480:
1.14 markus 481: /*
482: * Removes all identities from the agent. This call is not meant to be used
483: * by normal applications.
484: */
1.1 deraadt 485:
1.18 markus 486: int
1.25 ! markus 487: ssh_remove_all_identities(AuthenticationConnection *auth, int version)
1.1 deraadt 488: {
1.25 ! markus 489: Buffer msg;
1.24 markus 490: int type;
1.25 ! markus 491: int code = (version==1) ?
! 492: SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
! 493: SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
1.12 markus 494:
1.25 ! markus 495: buffer_init(&msg);
! 496: buffer_put_char(&msg, code);
1.12 markus 497:
1.25 ! markus 498: if (ssh_request_reply(auth, &msg, &msg) == 0) {
! 499: buffer_free(&msg);
1.12 markus 500: return 0;
501: }
1.25 ! markus 502: type = buffer_get_char(&msg);
! 503: buffer_free(&msg);
1.24 markus 504: return decode_reply(type);
1.21 markus 505: }
506:
507: int
1.24 markus 508: decode_reply(int type)
1.21 markus 509: {
1.12 markus 510: switch (type) {
511: case SSH_AGENT_FAILURE:
1.24 markus 512: log("SSH_AGENT_FAILURE");
1.12 markus 513: return 0;
514: case SSH_AGENT_SUCCESS:
515: return 1;
516: default:
1.21 markus 517: fatal("Bad response from authentication agent: %d", type);
1.12 markus 518: }
519: /* NOTREACHED */
520: return 0;
521: }
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