Annotation of src/usr.bin/ssh/authfd.c, Revision 1.29.2.4
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
1.27 deraadt 5: * Functions for connecting the local authentication agent.
1.18 markus 6: *
1.27 deraadt 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".
1.18 markus 12: *
1.25 markus 13: * SSH2 implementation,
1.27 deraadt 14: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.25 markus 15: *
1.27 deraadt 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.
24: *
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"
1.29.2.4! jason 38: RCSID("$OpenBSD: authfd.c,v 1.39 2001/04/05 10:42:48 markus Exp $");
1.29.2.1 jason 39:
40: #include <openssl/evp.h>
1.1 deraadt 41:
42: #include "ssh.h"
43: #include "rsa.h"
44: #include "buffer.h"
45: #include "bufaux.h"
46: #include "xmalloc.h"
47: #include "getput.h"
1.22 markus 48: #include "key.h"
49: #include "authfd.h"
1.29.2.1 jason 50: #include "cipher.h"
1.22 markus 51: #include "kex.h"
1.28 markus 52: #include "compat.h"
1.29.2.1 jason 53: #include "log.h"
54: #include "atomicio.h"
1.2 provos 55:
1.21 markus 56: /* helper */
1.24 markus 57: int decode_reply(int type);
1.21 markus 58:
1.29 markus 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
1.29.2.1 jason 66: ssh_get_authentication_socket(void)
1.1 deraadt 67: {
1.12 markus 68: const char *authsocket;
1.23 deraadt 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));
1.29.2.3 jason 78: len = SUN_LEN(&sunaddr)+1;
79: sunaddr.sun_len = len;
1.12 markus 80:
81: sock = socket(AF_UNIX, SOCK_STREAM, 0);
82: if (sock < 0)
83: return -1;
84:
85: /* close on exec */
86: if (fcntl(sock, F_SETFD, 1) == -1) {
87: close(sock);
88: return -1;
89: }
1.23 deraadt 90: if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) {
1.12 markus 91: close(sock);
92: return -1;
93: }
94: return sock;
1.1 deraadt 95: }
96:
1.24 markus 97: int
1.25 markus 98: ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
1.24 markus 99: {
100: int l, len;
101: char buf[1024];
102:
103: /* Get the length of the message, and format it in the buffer. */
104: len = buffer_len(request);
105: PUT_32BIT(buf, len);
106:
107: /* Send the length and then the packet to the agent. */
108: if (atomicio(write, auth->fd, buf, 4) != 4 ||
109: atomicio(write, auth->fd, buffer_ptr(request),
110: buffer_len(request)) != buffer_len(request)) {
111: error("Error writing to authentication socket.");
112: return 0;
113: }
114: /*
115: * Wait for response from the agent. First read the length of the
116: * response packet.
117: */
118: len = 4;
119: while (len > 0) {
120: l = read(auth->fd, buf + 4 - len, len);
1.29.2.3 jason 121: if (l == -1 && (errno == EAGAIN || errno == EINTR))
1.29.2.4! jason 122: continue;
1.24 markus 123: if (l <= 0) {
124: error("Error reading response length from authentication socket.");
125: return 0;
126: }
127: len -= l;
128: }
129:
130: /* Extract the length, and check it for sanity. */
131: len = GET_32BIT(buf);
132: if (len > 256 * 1024)
133: fatal("Authentication response too long: %d", len);
134:
135: /* Read the rest of the response in to the buffer. */
136: buffer_clear(reply);
137: while (len > 0) {
138: l = len;
139: if (l > sizeof(buf))
140: l = sizeof(buf);
141: l = read(auth->fd, buf, l);
1.29.2.3 jason 142: if (l == -1 && (errno == EAGAIN || errno == EINTR))
1.29.2.4! jason 143: continue;
1.24 markus 144: if (l <= 0) {
145: error("Error reading response from authentication socket.");
146: return 0;
147: }
148: buffer_append(reply, (char *) buf, l);
149: len -= l;
150: }
151: return 1;
152: }
153:
1.14 markus 154: /*
155: * Closes the agent socket if it should be closed (depends on how it was
156: * obtained). The argument must have been returned by
157: * ssh_get_authentication_socket().
158: */
1.1 deraadt 159:
1.18 markus 160: void
1.12 markus 161: ssh_close_authentication_socket(int sock)
1.1 deraadt 162: {
1.12 markus 163: if (getenv(SSH_AUTHSOCKET_ENV_NAME))
164: close(sock);
1.1 deraadt 165: }
166:
1.14 markus 167: /*
168: * Opens and connects a private socket for communication with the
169: * authentication agent. Returns the file descriptor (which must be
170: * shut down and closed by the caller when no longer needed).
171: * Returns NULL if an error occurred and the connection could not be
172: * opened.
173: */
1.1 deraadt 174:
1.12 markus 175: AuthenticationConnection *
1.29.2.1 jason 176: ssh_get_authentication_connection(void)
1.1 deraadt 177: {
1.12 markus 178: AuthenticationConnection *auth;
179: int sock;
1.1 deraadt 180:
1.12 markus 181: sock = ssh_get_authentication_socket();
182:
1.14 markus 183: /*
184: * Fail if we couldn't obtain a connection. This happens if we
185: * exited due to a timeout.
186: */
1.12 markus 187: if (sock < 0)
188: return NULL;
189:
190: auth = xmalloc(sizeof(*auth));
191: auth->fd = sock;
192: buffer_init(&auth->identities);
193: auth->howmany = 0;
194:
195: return auth;
1.1 deraadt 196: }
197:
1.14 markus 198: /*
199: * Closes the connection to the authentication agent and frees any associated
200: * memory.
201: */
1.1 deraadt 202:
1.18 markus 203: void
1.25 markus 204: ssh_close_authentication_connection(AuthenticationConnection *auth)
1.1 deraadt 205: {
1.25 markus 206: buffer_free(&auth->identities);
207: close(auth->fd);
208: xfree(auth);
1.1 deraadt 209: }
210:
1.14 markus 211: /*
212: * Returns the first authentication identity held by the agent.
213: */
1.1 deraadt 214:
1.29.2.1 jason 215: int
216: ssh_get_num_identities(AuthenticationConnection *auth, int version)
1.1 deraadt 217: {
1.25 markus 218: int type, code1 = 0, code2 = 0;
1.24 markus 219: Buffer request;
1.25 markus 220:
221: switch(version){
222: case 1:
223: code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
224: code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
225: break;
226: case 2:
227: code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
228: code2 = SSH2_AGENT_IDENTITIES_ANSWER;
229: break;
230: default:
1.29.2.1 jason 231: return 0;
1.25 markus 232: }
1.1 deraadt 233:
1.14 markus 234: /*
235: * Send a message to the agent requesting for a list of the
236: * identities it can represent.
237: */
1.24 markus 238: buffer_init(&request);
1.25 markus 239: buffer_put_char(&request, code1);
1.12 markus 240:
241: buffer_clear(&auth->identities);
1.24 markus 242: if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
243: buffer_free(&request);
1.29.2.1 jason 244: return 0;
1.12 markus 245: }
1.24 markus 246: buffer_free(&request);
1.1 deraadt 247:
1.12 markus 248: /* Get message type, and verify that we got a proper answer. */
1.24 markus 249: type = buffer_get_char(&auth->identities);
1.29 markus 250: if (agent_failed(type)) {
1.29.2.1 jason 251: return 0;
1.25 markus 252: } else if (type != code2) {
1.24 markus 253: fatal("Bad authentication reply message type: %d", type);
1.25 markus 254: }
1.12 markus 255:
256: /* Get the number of entries in the response and check it for sanity. */
257: auth->howmany = buffer_get_int(&auth->identities);
258: if (auth->howmany > 1024)
1.29.2.3 jason 259: fatal("Too many identities in authentication reply: %d",
1.24 markus 260: auth->howmany);
1.12 markus 261:
1.29.2.1 jason 262: return auth->howmany;
263: }
264:
265: Key *
266: ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
267: {
268: /* get number of identities and return the first entry (if any). */
269: if (ssh_get_num_identities(auth, version) > 0)
270: return ssh_get_next_identity(auth, comment, version);
271: return NULL;
1.1 deraadt 272: }
273:
1.25 markus 274: Key *
275: ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
1.1 deraadt 276: {
1.29.2.1 jason 277: u_int bits;
278: u_char *blob;
279: u_int blen;
1.25 markus 280: Key *key = NULL;
1.9 markus 281:
1.12 markus 282: /* Return failure if no more entries. */
283: if (auth->howmany <= 0)
1.25 markus 284: return NULL;
1.12 markus 285:
1.14 markus 286: /*
287: * Get the next entry from the packet. These will abort with a fatal
288: * error if the packet is too short or contains corrupt data.
289: */
1.25 markus 290: switch(version){
291: case 1:
1.29.2.1 jason 292: key = key_new(KEY_RSA1);
1.25 markus 293: bits = buffer_get_int(&auth->identities);
294: buffer_get_bignum(&auth->identities, key->rsa->e);
295: buffer_get_bignum(&auth->identities, key->rsa->n);
296: *comment = buffer_get_string(&auth->identities, NULL);
297: if (bits != BN_num_bits(key->rsa->n))
298: log("Warning: identity keysize mismatch: actual %d, announced %u",
299: BN_num_bits(key->rsa->n), bits);
300: break;
301: case 2:
302: blob = buffer_get_string(&auth->identities, &blen);
303: *comment = buffer_get_string(&auth->identities, NULL);
1.29.2.1 jason 304: key = key_from_blob(blob, blen);
1.25 markus 305: xfree(blob);
306: break;
307: default:
308: return NULL;
309: break;
310: }
1.12 markus 311: /* Decrement the number of remaining entries. */
312: auth->howmany--;
1.25 markus 313: return key;
1.1 deraadt 314: }
315:
1.14 markus 316: /*
317: * Generates a random challenge, sends it to the agent, and waits for
318: * response from the agent. Returns true (non-zero) if the agent gave the
319: * correct answer, zero otherwise. Response type selects the style of
320: * response desired, with 0 corresponding to protocol version 1.0 (no longer
321: * supported) and 1 corresponding to protocol version 1.1.
322: */
1.1 deraadt 323:
1.2 provos 324: int
325: ssh_decrypt_challenge(AuthenticationConnection *auth,
1.25 markus 326: Key* key, BIGNUM *challenge,
1.29.2.1 jason 327: u_char session_id[16],
328: u_int response_type,
329: u_char response[16])
1.1 deraadt 330: {
1.12 markus 331: Buffer buffer;
1.24 markus 332: int success = 0;
333: int i;
334: int type;
1.12 markus 335:
1.29.2.1 jason 336: if (key->type != KEY_RSA1)
1.25 markus 337: return 0;
338: if (response_type == 0) {
339: log("Compatibility with ssh protocol version 1.0 no longer supported.");
340: return 0;
341: }
1.12 markus 342: buffer_init(&buffer);
1.24 markus 343: buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
1.25 markus 344: buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
345: buffer_put_bignum(&buffer, key->rsa->e);
346: buffer_put_bignum(&buffer, key->rsa->n);
1.12 markus 347: buffer_put_bignum(&buffer, challenge);
348: buffer_append(&buffer, (char *) session_id, 16);
349: buffer_put_int(&buffer, response_type);
350:
1.24 markus 351: if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
1.12 markus 352: buffer_free(&buffer);
353: return 0;
354: }
1.24 markus 355: type = buffer_get_char(&buffer);
1.12 markus 356:
1.29 markus 357: if (agent_failed(type)) {
1.12 markus 358: log("Agent admitted failure to authenticate using the key.");
1.24 markus 359: } else if (type != SSH_AGENT_RSA_RESPONSE) {
360: fatal("Bad authentication response: %d", type);
361: } else {
362: success = 1;
363: /*
364: * Get the response from the packet. This will abort with a
365: * fatal error if the packet is corrupt.
366: */
367: for (i = 0; i < 16; i++)
368: response[i] = buffer_get_char(&buffer);
1.12 markus 369: }
370: buffer_free(&buffer);
1.24 markus 371: return success;
1.12 markus 372: }
1.1 deraadt 373:
1.25 markus 374: /* ask agent to sign data, returns -1 on error, 0 on success */
375: int
376: ssh_agent_sign(AuthenticationConnection *auth,
377: Key *key,
1.29.2.1 jason 378: u_char **sigp, int *lenp,
379: u_char *data, int datalen)
1.25 markus 380: {
1.28 markus 381: extern int datafellows;
1.25 markus 382: Buffer msg;
1.29.2.1 jason 383: u_char *blob;
384: u_int blen;
1.28 markus 385: int type, flags = 0;
1.25 markus 386: int ret = -1;
387:
1.29.2.1 jason 388: if (key_to_blob(key, &blob, &blen) == 0)
1.25 markus 389: return -1;
390:
1.28 markus 391: if (datafellows & SSH_BUG_SIGBLOB)
392: flags = SSH_AGENT_OLD_SIGNATURE;
393:
1.25 markus 394: buffer_init(&msg);
395: buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
396: buffer_put_string(&msg, blob, blen);
397: buffer_put_string(&msg, data, datalen);
1.28 markus 398: buffer_put_int(&msg, flags);
1.25 markus 399: xfree(blob);
400:
401: if (ssh_request_reply(auth, &msg, &msg) == 0) {
402: buffer_free(&msg);
403: return -1;
404: }
405: type = buffer_get_char(&msg);
1.29 markus 406: if (agent_failed(type)) {
1.25 markus 407: log("Agent admitted failure to sign using the key.");
408: } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
409: fatal("Bad authentication response: %d", type);
410: } else {
411: ret = 0;
412: *sigp = buffer_get_string(&msg, lenp);
413: }
414: buffer_free(&msg);
415: return ret;
416: }
417:
1.22 markus 418: /* Encode key for a message to the agent. */
419:
420: void
1.29.2.1 jason 421: ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
1.22 markus 422: {
423: buffer_clear(b);
424: buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
425: buffer_put_int(b, BN_num_bits(key->n));
426: buffer_put_bignum(b, key->n);
427: buffer_put_bignum(b, key->e);
428: buffer_put_bignum(b, key->d);
429: /* To keep within the protocol: p < q for ssh. in SSL p > q */
430: buffer_put_bignum(b, key->iqmp); /* ssh key->u */
431: buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
432: buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
433: buffer_put_string(b, comment, strlen(comment));
434: }
435:
436: void
1.29.2.1 jason 437: ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
1.22 markus 438: {
439: buffer_clear(b);
440: buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
1.29.2.1 jason 441: buffer_put_cstring(b, key_ssh_name(key));
442: switch(key->type){
443: case KEY_RSA:
444: buffer_put_bignum2(b, key->rsa->n);
445: buffer_put_bignum2(b, key->rsa->e);
446: buffer_put_bignum2(b, key->rsa->d);
447: buffer_put_bignum2(b, key->rsa->iqmp);
448: buffer_put_bignum2(b, key->rsa->p);
449: buffer_put_bignum2(b, key->rsa->q);
450: break;
451: case KEY_DSA:
452: buffer_put_bignum2(b, key->dsa->p);
453: buffer_put_bignum2(b, key->dsa->q);
454: buffer_put_bignum2(b, key->dsa->g);
455: buffer_put_bignum2(b, key->dsa->pub_key);
456: buffer_put_bignum2(b, key->dsa->priv_key);
457: break;
458: }
459: buffer_put_cstring(b, comment);
1.22 markus 460: }
461:
1.14 markus 462: /*
463: * Adds an identity to the authentication server. This call is not meant to
464: * be used by normal applications.
465: */
1.1 deraadt 466:
1.18 markus 467: int
1.22 markus 468: ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
1.1 deraadt 469: {
1.25 markus 470: Buffer msg;
1.24 markus 471: int type;
1.12 markus 472:
1.25 markus 473: buffer_init(&msg);
1.22 markus 474:
475: switch (key->type) {
1.29.2.1 jason 476: case KEY_RSA1:
477: ssh_encode_identity_rsa1(&msg, key->rsa, comment);
1.22 markus 478: break;
1.29.2.1 jason 479: case KEY_RSA:
1.22 markus 480: case KEY_DSA:
1.29.2.1 jason 481: ssh_encode_identity_ssh2(&msg, key, comment);
1.22 markus 482: break;
483: default:
1.25 markus 484: buffer_free(&msg);
1.22 markus 485: return 0;
486: break;
487: }
1.25 markus 488: if (ssh_request_reply(auth, &msg, &msg) == 0) {
489: buffer_free(&msg);
1.12 markus 490: return 0;
491: }
1.25 markus 492: type = buffer_get_char(&msg);
493: buffer_free(&msg);
1.24 markus 494: return decode_reply(type);
1.12 markus 495: }
1.1 deraadt 496:
1.14 markus 497: /*
498: * Removes an identity from the authentication server. This call is not
499: * meant to be used by normal applications.
500: */
1.1 deraadt 501:
1.18 markus 502: int
1.25 markus 503: ssh_remove_identity(AuthenticationConnection *auth, Key *key)
1.1 deraadt 504: {
1.25 markus 505: Buffer msg;
1.24 markus 506: int type;
1.29.2.1 jason 507: u_char *blob;
508: u_int blen;
1.12 markus 509:
1.25 markus 510: buffer_init(&msg);
1.12 markus 511:
1.29.2.1 jason 512: if (key->type == KEY_RSA1) {
1.25 markus 513: buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
514: buffer_put_int(&msg, BN_num_bits(key->rsa->n));
515: buffer_put_bignum(&msg, key->rsa->e);
516: buffer_put_bignum(&msg, key->rsa->n);
1.29.2.1 jason 517: } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
518: key_to_blob(key, &blob, &blen);
1.25 markus 519: buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
520: buffer_put_string(&msg, blob, blen);
521: xfree(blob);
522: } else {
523: buffer_free(&msg);
524: return 0;
525: }
526: if (ssh_request_reply(auth, &msg, &msg) == 0) {
527: buffer_free(&msg);
1.12 markus 528: return 0;
529: }
1.25 markus 530: type = buffer_get_char(&msg);
531: buffer_free(&msg);
1.24 markus 532: return decode_reply(type);
1.12 markus 533: }
534:
1.14 markus 535: /*
536: * Removes all identities from the agent. This call is not meant to be used
537: * by normal applications.
538: */
1.1 deraadt 539:
1.18 markus 540: int
1.25 markus 541: ssh_remove_all_identities(AuthenticationConnection *auth, int version)
1.1 deraadt 542: {
1.25 markus 543: Buffer msg;
1.24 markus 544: int type;
1.25 markus 545: int code = (version==1) ?
546: SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
547: SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
1.12 markus 548:
1.25 markus 549: buffer_init(&msg);
550: buffer_put_char(&msg, code);
1.12 markus 551:
1.25 markus 552: if (ssh_request_reply(auth, &msg, &msg) == 0) {
553: buffer_free(&msg);
1.12 markus 554: return 0;
555: }
1.25 markus 556: type = buffer_get_char(&msg);
557: buffer_free(&msg);
1.24 markus 558: return decode_reply(type);
1.21 markus 559: }
560:
1.29.2.1 jason 561: int
1.24 markus 562: decode_reply(int type)
1.21 markus 563: {
1.12 markus 564: switch (type) {
565: case SSH_AGENT_FAILURE:
1.29 markus 566: case SSH_COM_AGENT2_FAILURE:
1.24 markus 567: log("SSH_AGENT_FAILURE");
1.12 markus 568: return 0;
569: case SSH_AGENT_SUCCESS:
570: return 1;
571: default:
1.21 markus 572: fatal("Bad response from authentication agent: %d", type);
1.12 markus 573: }
574: /* NOTREACHED */
575: return 0;
576: }