Annotation of src/usr.bin/ssh/authfd.c, Revision 1.19.2.2
1.1 deraadt 1: /*
1.13 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Functions for connecting the local authentication agent.
1.18 markus 6: *
1.19.2.2! jason 7: * As far as I am concerned, the code I have written for this software
! 8: * can be used freely for any purpose. Any derived versions of this
! 9: * software must be clearly marked as such, and if the derived work is
! 10: * incompatible with the protocol description in the RFC file, it must be
! 11: * called by a name other than "ssh" or "Secure Shell".
! 12: *
1.19.2.1 jason 13: * SSH2 implementation,
1.19.2.2! jason 14: * Copyright (c) 2000 Markus Friedl. All rights reserved.
! 15: *
! 16: * Redistribution and use in source and binary forms, with or without
! 17: * modification, are permitted provided that the following conditions
! 18: * are met:
! 19: * 1. Redistributions of source code must retain the above copyright
! 20: * notice, this list of conditions and the following disclaimer.
! 21: * 2. Redistributions in binary form must reproduce the above copyright
! 22: * notice, this list of conditions and the following disclaimer in the
! 23: * documentation and/or other materials provided with the distribution.
1.19.2.1 jason 24: *
1.19.2.2! jason 25: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
! 26: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
! 27: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
! 28: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
! 29: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
! 30: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
! 31: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
! 32: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
! 33: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
! 34: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.13 deraadt 35: */
1.1 deraadt 36:
37: #include "includes.h"
1.19.2.2! jason 38: RCSID("$OpenBSD: authfd.c,v 1.29 2000/10/09 21:51:00 markus Exp $");
1.1 deraadt 39:
40: #include "ssh.h"
41: #include "rsa.h"
42: #include "buffer.h"
43: #include "bufaux.h"
44: #include "xmalloc.h"
45: #include "getput.h"
46:
1.17 markus 47: #include <openssl/rsa.h>
1.19.2.1 jason 48: #include <openssl/dsa.h>
49: #include <openssl/evp.h>
50: #include "key.h"
51: #include "authfd.h"
52: #include "kex.h"
53: #include "dsa.h"
1.19.2.2! jason 54: #include "compat.h"
1.19.2.1 jason 55:
56: /* helper */
57: int decode_reply(int type);
1.2 provos 58:
1.19.2.2! jason 59: /* macro to check for "agent failure" message */
! 60: #define agent_failed(x) \
! 61: ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE))
! 62:
1.1 deraadt 63: /* Returns the number of the authentication fd, or -1 if there is none. */
64:
1.2 provos 65: int
1.8 markus 66: ssh_get_authentication_socket()
1.1 deraadt 67: {
1.12 markus 68: const char *authsocket;
1.19.2.1 jason 69: int sock, len;
1.12 markus 70: struct sockaddr_un sunaddr;
71:
72: authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
73: if (!authsocket)
74: return -1;
75:
76: sunaddr.sun_family = AF_UNIX;
77: strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
1.19.2.1 jason 78: sunaddr.sun_len = len = SUN_LEN(&sunaddr)+1;
1.12 markus 79:
80: sock = socket(AF_UNIX, SOCK_STREAM, 0);
81: if (sock < 0)
82: return -1;
83:
84: /* close on exec */
85: if (fcntl(sock, F_SETFD, 1) == -1) {
86: close(sock);
87: return -1;
88: }
1.19.2.1 jason 89: if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) {
1.12 markus 90: close(sock);
91: return -1;
92: }
93: return sock;
1.1 deraadt 94: }
95:
1.19.2.1 jason 96: int
97: ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
98: {
99: int l, len;
100: char buf[1024];
101:
102: /* Get the length of the message, and format it in the buffer. */
103: len = buffer_len(request);
104: PUT_32BIT(buf, len);
105:
106: /* Send the length and then the packet to the agent. */
107: if (atomicio(write, auth->fd, buf, 4) != 4 ||
108: atomicio(write, auth->fd, buffer_ptr(request),
109: buffer_len(request)) != buffer_len(request)) {
110: error("Error writing to authentication socket.");
111: return 0;
112: }
113: /*
114: * Wait for response from the agent. First read the length of the
115: * response packet.
116: */
117: len = 4;
118: while (len > 0) {
119: l = read(auth->fd, buf + 4 - len, len);
120: if (l <= 0) {
121: error("Error reading response length from authentication socket.");
122: return 0;
123: }
124: len -= l;
125: }
126:
127: /* Extract the length, and check it for sanity. */
128: len = GET_32BIT(buf);
129: if (len > 256 * 1024)
130: fatal("Authentication response too long: %d", len);
131:
132: /* Read the rest of the response in to the buffer. */
133: buffer_clear(reply);
134: while (len > 0) {
135: l = len;
136: if (l > sizeof(buf))
137: l = sizeof(buf);
138: l = read(auth->fd, buf, l);
139: if (l <= 0) {
140: error("Error reading response from authentication socket.");
141: return 0;
142: }
143: buffer_append(reply, (char *) buf, l);
144: len -= l;
145: }
146: return 1;
147: }
148:
1.14 markus 149: /*
150: * Closes the agent socket if it should be closed (depends on how it was
151: * obtained). The argument must have been returned by
152: * ssh_get_authentication_socket().
153: */
1.1 deraadt 154:
1.18 markus 155: void
1.12 markus 156: ssh_close_authentication_socket(int sock)
1.1 deraadt 157: {
1.12 markus 158: if (getenv(SSH_AUTHSOCKET_ENV_NAME))
159: close(sock);
1.1 deraadt 160: }
161:
1.14 markus 162: /*
163: * Opens and connects a private socket for communication with the
164: * authentication agent. Returns the file descriptor (which must be
165: * shut down and closed by the caller when no longer needed).
166: * Returns NULL if an error occurred and the connection could not be
167: * opened.
168: */
1.1 deraadt 169:
1.12 markus 170: AuthenticationConnection *
171: ssh_get_authentication_connection()
1.1 deraadt 172: {
1.12 markus 173: AuthenticationConnection *auth;
174: int sock;
1.1 deraadt 175:
1.12 markus 176: sock = ssh_get_authentication_socket();
177:
1.14 markus 178: /*
179: * Fail if we couldn't obtain a connection. This happens if we
180: * exited due to a timeout.
181: */
1.12 markus 182: if (sock < 0)
183: return NULL;
184:
185: auth = xmalloc(sizeof(*auth));
186: auth->fd = sock;
187: buffer_init(&auth->identities);
188: auth->howmany = 0;
189:
190: return auth;
1.1 deraadt 191: }
192:
1.14 markus 193: /*
194: * Closes the connection to the authentication agent and frees any associated
195: * memory.
196: */
1.1 deraadt 197:
1.18 markus 198: void
1.19.2.1 jason 199: ssh_close_authentication_connection(AuthenticationConnection *auth)
1.1 deraadt 200: {
1.19.2.1 jason 201: buffer_free(&auth->identities);
202: close(auth->fd);
203: xfree(auth);
1.1 deraadt 204: }
205:
1.14 markus 206: /*
207: * Returns the first authentication identity held by the agent.
208: */
1.1 deraadt 209:
1.19.2.1 jason 210: Key *
211: ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
1.1 deraadt 212: {
1.19.2.1 jason 213: int type, code1 = 0, code2 = 0;
214: Buffer request;
1.1 deraadt 215:
1.19.2.1 jason 216: switch(version){
217: case 1:
218: code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
219: code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
220: break;
221: case 2:
222: code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
223: code2 = SSH2_AGENT_IDENTITIES_ANSWER;
224: break;
225: default:
226: return NULL;
1.12 markus 227: }
228:
1.14 markus 229: /*
1.19.2.1 jason 230: * Send a message to the agent requesting for a list of the
231: * identities it can represent.
1.14 markus 232: */
1.19.2.1 jason 233: buffer_init(&request);
234: buffer_put_char(&request, code1);
1.12 markus 235:
236: buffer_clear(&auth->identities);
1.19.2.1 jason 237: if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
238: buffer_free(&request);
239: return NULL;
1.12 markus 240: }
1.19.2.1 jason 241: buffer_free(&request);
1.1 deraadt 242:
1.12 markus 243: /* Get message type, and verify that we got a proper answer. */
1.19.2.1 jason 244: type = buffer_get_char(&auth->identities);
1.19.2.2! jason 245: if (agent_failed(type)) {
1.19.2.1 jason 246: return NULL;
247: } else if (type != code2) {
248: fatal("Bad authentication reply message type: %d", type);
249: }
1.12 markus 250:
251: /* Get the number of entries in the response and check it for sanity. */
252: auth->howmany = buffer_get_int(&auth->identities);
253: if (auth->howmany > 1024)
1.19.2.1 jason 254: fatal("Too many identities in authentication reply: %d\n",
255: auth->howmany);
1.12 markus 256:
257: /* Return the first entry (if any). */
1.19.2.1 jason 258: return ssh_get_next_identity(auth, comment, version);
1.1 deraadt 259: }
260:
1.19.2.1 jason 261: Key *
262: ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
1.1 deraadt 263: {
1.12 markus 264: unsigned int bits;
1.19.2.1 jason 265: unsigned char *blob;
266: unsigned int blen;
267: Key *key = NULL;
1.9 markus 268:
1.12 markus 269: /* Return failure if no more entries. */
270: if (auth->howmany <= 0)
1.19.2.1 jason 271: return NULL;
1.12 markus 272:
1.14 markus 273: /*
274: * Get the next entry from the packet. These will abort with a fatal
275: * error if the packet is too short or contains corrupt data.
276: */
1.19.2.1 jason 277: switch(version){
278: case 1:
279: key = key_new(KEY_RSA);
280: bits = buffer_get_int(&auth->identities);
281: buffer_get_bignum(&auth->identities, key->rsa->e);
282: buffer_get_bignum(&auth->identities, key->rsa->n);
283: *comment = buffer_get_string(&auth->identities, NULL);
284: if (bits != BN_num_bits(key->rsa->n))
285: log("Warning: identity keysize mismatch: actual %d, announced %u",
286: BN_num_bits(key->rsa->n), bits);
287: break;
288: case 2:
289: blob = buffer_get_string(&auth->identities, &blen);
290: *comment = buffer_get_string(&auth->identities, NULL);
291: key = dsa_key_from_blob(blob, blen);
292: xfree(blob);
293: break;
294: default:
295: return NULL;
296: break;
297: }
1.12 markus 298: /* Decrement the number of remaining entries. */
299: auth->howmany--;
1.19.2.1 jason 300: return key;
1.1 deraadt 301: }
302:
1.14 markus 303: /*
304: * Generates a random challenge, sends it to the agent, and waits for
305: * response from the agent. Returns true (non-zero) if the agent gave the
306: * correct answer, zero otherwise. Response type selects the style of
307: * response desired, with 0 corresponding to protocol version 1.0 (no longer
308: * supported) and 1 corresponding to protocol version 1.1.
309: */
1.1 deraadt 310:
1.2 provos 311: int
312: ssh_decrypt_challenge(AuthenticationConnection *auth,
1.19.2.1 jason 313: Key* key, BIGNUM *challenge,
314: unsigned char session_id[16],
315: unsigned int response_type,
316: unsigned char response[16])
1.1 deraadt 317: {
1.12 markus 318: Buffer buffer;
1.19.2.1 jason 319: int success = 0;
320: int i;
321: int type;
1.12 markus 322:
1.19.2.1 jason 323: if (key->type != KEY_RSA)
324: return 0;
325: if (response_type == 0) {
326: log("Compatibility with ssh protocol version 1.0 no longer supported.");
327: return 0;
328: }
1.12 markus 329: buffer_init(&buffer);
1.19.2.1 jason 330: buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
331: buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
332: buffer_put_bignum(&buffer, key->rsa->e);
333: buffer_put_bignum(&buffer, key->rsa->n);
1.12 markus 334: buffer_put_bignum(&buffer, challenge);
335: buffer_append(&buffer, (char *) session_id, 16);
336: buffer_put_int(&buffer, response_type);
337:
1.19.2.1 jason 338: if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
1.12 markus 339: buffer_free(&buffer);
340: return 0;
341: }
1.19.2.1 jason 342: type = buffer_get_char(&buffer);
343:
1.19.2.2! jason 344: if (agent_failed(type)) {
1.19.2.1 jason 345: log("Agent admitted failure to authenticate using the key.");
346: } else if (type != SSH_AGENT_RSA_RESPONSE) {
347: fatal("Bad authentication response: %d", type);
348: } else {
349: success = 1;
350: /*
351: * Get the response from the packet. This will abort with a
352: * fatal error if the packet is corrupt.
353: */
354: for (i = 0; i < 16; i++)
355: response[i] = buffer_get_char(&buffer);
1.12 markus 356: }
1.19.2.1 jason 357: buffer_free(&buffer);
358: return success;
359: }
1.12 markus 360:
1.19.2.1 jason 361: /* ask agent to sign data, returns -1 on error, 0 on success */
362: int
363: ssh_agent_sign(AuthenticationConnection *auth,
364: Key *key,
365: unsigned char **sigp, int *lenp,
366: unsigned char *data, int datalen)
367: {
1.19.2.2! jason 368: extern int datafellows;
1.19.2.1 jason 369: Buffer msg;
370: unsigned char *blob;
371: unsigned int blen;
1.19.2.2! jason 372: int type, flags = 0;
1.19.2.1 jason 373: int ret = -1;
1.12 markus 374:
1.19.2.1 jason 375: if (dsa_make_key_blob(key, &blob, &blen) == 0)
376: return -1;
1.12 markus 377:
1.19.2.2! jason 378: if (datafellows & SSH_BUG_SIGBLOB)
! 379: flags = SSH_AGENT_OLD_SIGNATURE;
! 380:
1.19.2.1 jason 381: buffer_init(&msg);
382: buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
383: buffer_put_string(&msg, blob, blen);
384: buffer_put_string(&msg, data, datalen);
1.19.2.2! jason 385: buffer_put_int(&msg, flags);
1.19.2.1 jason 386: xfree(blob);
1.12 markus 387:
1.19.2.1 jason 388: if (ssh_request_reply(auth, &msg, &msg) == 0) {
389: buffer_free(&msg);
390: return -1;
391: }
392: type = buffer_get_char(&msg);
1.19.2.2! jason 393: if (agent_failed(type)) {
1.19.2.1 jason 394: log("Agent admitted failure to sign using the key.");
395: } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
396: fatal("Bad authentication response: %d", type);
397: } else {
398: ret = 0;
399: *sigp = buffer_get_string(&msg, lenp);
1.12 markus 400: }
1.19.2.1 jason 401: buffer_free(&msg);
402: return ret;
403: }
1.12 markus 404:
1.19.2.1 jason 405: /* Encode key for a message to the agent. */
1.12 markus 406:
1.19.2.1 jason 407: void
408: ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment)
409: {
410: buffer_clear(b);
411: buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
412: buffer_put_int(b, BN_num_bits(key->n));
413: buffer_put_bignum(b, key->n);
414: buffer_put_bignum(b, key->e);
415: buffer_put_bignum(b, key->d);
416: /* To keep within the protocol: p < q for ssh. in SSL p > q */
417: buffer_put_bignum(b, key->iqmp); /* ssh key->u */
418: buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
419: buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
420: buffer_put_string(b, comment, strlen(comment));
421: }
1.12 markus 422:
1.19.2.1 jason 423: void
424: ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment)
425: {
426: buffer_clear(b);
427: buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
428: buffer_put_cstring(b, KEX_DSS);
429: buffer_put_bignum2(b, key->p);
430: buffer_put_bignum2(b, key->q);
431: buffer_put_bignum2(b, key->g);
432: buffer_put_bignum2(b, key->pub_key);
433: buffer_put_bignum2(b, key->priv_key);
434: buffer_put_string(b, comment, strlen(comment));
1.12 markus 435: }
1.1 deraadt 436:
1.14 markus 437: /*
438: * Adds an identity to the authentication server. This call is not meant to
439: * be used by normal applications.
440: */
1.1 deraadt 441:
1.18 markus 442: int
1.19.2.1 jason 443: ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
1.1 deraadt 444: {
1.19.2.1 jason 445: Buffer msg;
446: int type;
1.12 markus 447:
1.19.2.1 jason 448: buffer_init(&msg);
1.12 markus 449:
1.19.2.1 jason 450: switch (key->type) {
451: case KEY_RSA:
452: ssh_encode_identity_rsa(&msg, key->rsa, comment);
453: break;
454: case KEY_DSA:
455: ssh_encode_identity_dsa(&msg, key->dsa, comment);
456: break;
457: default:
458: buffer_free(&msg);
1.12 markus 459: return 0;
1.19.2.1 jason 460: break;
1.12 markus 461: }
1.19.2.1 jason 462: if (ssh_request_reply(auth, &msg, &msg) == 0) {
463: buffer_free(&msg);
1.12 markus 464: return 0;
465: }
1.19.2.1 jason 466: type = buffer_get_char(&msg);
467: buffer_free(&msg);
468: return decode_reply(type);
1.12 markus 469: }
1.1 deraadt 470:
1.14 markus 471: /*
472: * Removes an identity from the authentication server. This call is not
473: * meant to be used by normal applications.
474: */
1.1 deraadt 475:
1.18 markus 476: int
1.19.2.1 jason 477: ssh_remove_identity(AuthenticationConnection *auth, Key *key)
1.1 deraadt 478: {
1.19.2.1 jason 479: Buffer msg;
480: int type;
481: unsigned char *blob;
482: unsigned int blen;
483:
484: buffer_init(&msg);
485:
486: if (key->type == KEY_RSA) {
487: buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
488: buffer_put_int(&msg, BN_num_bits(key->rsa->n));
489: buffer_put_bignum(&msg, key->rsa->e);
490: buffer_put_bignum(&msg, key->rsa->n);
491: } else if (key->type == KEY_DSA) {
492: dsa_make_key_blob(key, &blob, &blen);
493: buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
494: buffer_put_string(&msg, blob, blen);
495: xfree(blob);
496: } else {
497: buffer_free(&msg);
1.12 markus 498: return 0;
499: }
1.19.2.1 jason 500: if (ssh_request_reply(auth, &msg, &msg) == 0) {
501: buffer_free(&msg);
1.12 markus 502: return 0;
503: }
1.19.2.1 jason 504: type = buffer_get_char(&msg);
505: buffer_free(&msg);
506: return decode_reply(type);
1.12 markus 507: }
508:
1.14 markus 509: /*
510: * Removes all identities from the agent. This call is not meant to be used
511: * by normal applications.
512: */
1.1 deraadt 513:
1.18 markus 514: int
1.19.2.1 jason 515: ssh_remove_all_identities(AuthenticationConnection *auth, int version)
1.1 deraadt 516: {
1.19.2.1 jason 517: Buffer msg;
518: int type;
519: int code = (version==1) ?
520: SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
521: SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
1.12 markus 522:
1.19.2.1 jason 523: buffer_init(&msg);
524: buffer_put_char(&msg, code);
1.12 markus 525:
1.19.2.1 jason 526: if (ssh_request_reply(auth, &msg, &msg) == 0) {
527: buffer_free(&msg);
1.12 markus 528: return 0;
529: }
1.19.2.1 jason 530: type = buffer_get_char(&msg);
531: buffer_free(&msg);
532: return decode_reply(type);
533: }
1.12 markus 534:
1.19.2.1 jason 535: int
536: decode_reply(int type)
537: {
1.12 markus 538: switch (type) {
539: case SSH_AGENT_FAILURE:
1.19.2.2! jason 540: case SSH_COM_AGENT2_FAILURE:
1.19.2.1 jason 541: log("SSH_AGENT_FAILURE");
1.12 markus 542: return 0;
543: case SSH_AGENT_SUCCESS:
544: return 1;
545: default:
1.19.2.1 jason 546: fatal("Bad response from authentication agent: %d", type);
1.12 markus 547: }
548: /* NOTREACHED */
549: return 0;
550: }
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