Annotation of src/usr.bin/ssh/authfd.c, Revision 1.23
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: *
1.13 deraadt 14: */
1.1 deraadt 15:
16: #include "includes.h"
1.23 ! deraadt 17: RCSID("$OpenBSD: authfd.c,v 1.22 2000/07/16 08:27:20 markus Exp $");
1.1 deraadt 18:
19: #include "ssh.h"
20: #include "rsa.h"
21: #include "buffer.h"
22: #include "bufaux.h"
23: #include "xmalloc.h"
24: #include "getput.h"
25:
1.17 markus 26: #include <openssl/rsa.h>
1.22 markus 27: #include <openssl/dsa.h>
28: #include <openssl/evp.h>
29: #include "key.h"
30: #include "authfd.h"
31: #include "kex.h"
1.2 provos 32:
1.21 markus 33: /* helper */
34: int ssh_agent_get_reply(AuthenticationConnection *auth);
35:
1.1 deraadt 36: /* Returns the number of the authentication fd, or -1 if there is none. */
37:
1.2 provos 38: int
1.8 markus 39: ssh_get_authentication_socket()
1.1 deraadt 40: {
1.12 markus 41: const char *authsocket;
1.23 ! deraadt 42: int sock, len;
1.12 markus 43: struct sockaddr_un sunaddr;
44:
45: authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
46: if (!authsocket)
47: return -1;
48:
49: sunaddr.sun_family = AF_UNIX;
50: strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
1.23 ! deraadt 51: sunaddr.sun_len = len = SUN_LEN(&sunaddr)+1;
1.12 markus 52:
53: sock = socket(AF_UNIX, SOCK_STREAM, 0);
54: if (sock < 0)
55: return -1;
56:
57: /* close on exec */
58: if (fcntl(sock, F_SETFD, 1) == -1) {
59: close(sock);
60: return -1;
61: }
1.23 ! deraadt 62: if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) {
1.12 markus 63: close(sock);
64: return -1;
65: }
66: return sock;
1.1 deraadt 67: }
68:
1.14 markus 69: /*
70: * Closes the agent socket if it should be closed (depends on how it was
71: * obtained). The argument must have been returned by
72: * ssh_get_authentication_socket().
73: */
1.1 deraadt 74:
1.18 markus 75: void
1.12 markus 76: ssh_close_authentication_socket(int sock)
1.1 deraadt 77: {
1.12 markus 78: if (getenv(SSH_AUTHSOCKET_ENV_NAME))
79: close(sock);
1.1 deraadt 80: }
81:
1.14 markus 82: /*
83: * Opens and connects a private socket for communication with the
84: * authentication agent. Returns the file descriptor (which must be
85: * shut down and closed by the caller when no longer needed).
86: * Returns NULL if an error occurred and the connection could not be
87: * opened.
88: */
1.1 deraadt 89:
1.12 markus 90: AuthenticationConnection *
91: ssh_get_authentication_connection()
1.1 deraadt 92: {
1.12 markus 93: AuthenticationConnection *auth;
94: int sock;
1.1 deraadt 95:
1.12 markus 96: sock = ssh_get_authentication_socket();
97:
1.14 markus 98: /*
99: * Fail if we couldn't obtain a connection. This happens if we
100: * exited due to a timeout.
101: */
1.12 markus 102: if (sock < 0)
103: return NULL;
104:
105: auth = xmalloc(sizeof(*auth));
106: auth->fd = sock;
107: buffer_init(&auth->packet);
108: buffer_init(&auth->identities);
109: auth->howmany = 0;
110:
111: return auth;
1.1 deraadt 112: }
113:
1.14 markus 114: /*
115: * Closes the connection to the authentication agent and frees any associated
116: * memory.
117: */
1.1 deraadt 118:
1.18 markus 119: void
1.12 markus 120: ssh_close_authentication_connection(AuthenticationConnection *ac)
1.1 deraadt 121: {
1.12 markus 122: buffer_free(&ac->packet);
123: buffer_free(&ac->identities);
124: close(ac->fd);
125: xfree(ac);
1.1 deraadt 126: }
127:
1.14 markus 128: /*
129: * Returns the first authentication identity held by the agent.
130: * Returns true if an identity is available, 0 otherwise.
131: * The caller must initialize the integers before the call, and free the
132: * comment after a successful call (before calling ssh_get_next_identity).
133: */
1.1 deraadt 134:
1.2 provos 135: int
136: ssh_get_first_identity(AuthenticationConnection *auth,
1.9 markus 137: BIGNUM *e, BIGNUM *n, char **comment)
1.1 deraadt 138: {
1.12 markus 139: unsigned char msg[8192];
140: int len, l;
1.1 deraadt 141:
1.14 markus 142: /*
143: * Send a message to the agent requesting for a list of the
144: * identities it can represent.
145: */
1.22 markus 146: PUT_32BIT(msg, 1);
1.12 markus 147: msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
1.15 deraadt 148: if (atomicio(write, auth->fd, msg, 5) != 5) {
1.12 markus 149: error("write auth->fd: %.100s", strerror(errno));
150: return 0;
151: }
152: /* Read the length of the response. XXX implement timeouts here. */
153: len = 4;
154: while (len > 0) {
155: l = read(auth->fd, msg + 4 - len, len);
156: if (l <= 0) {
157: error("read auth->fd: %.100s", strerror(errno));
158: return 0;
159: }
160: len -= l;
161: }
162:
1.14 markus 163: /*
164: * Extract the length, and check it for sanity. (We cannot trust
165: * authentication agents).
166: */
1.12 markus 167: len = GET_32BIT(msg);
168: if (len < 1 || len > 256 * 1024)
169: fatal("Authentication reply message too long: %d\n", len);
170:
171: /* Read the packet itself. */
172: buffer_clear(&auth->identities);
173: while (len > 0) {
174: l = len;
175: if (l > sizeof(msg))
176: l = sizeof(msg);
177: l = read(auth->fd, msg, l);
178: if (l <= 0)
179: fatal("Incomplete authentication reply.");
180: buffer_append(&auth->identities, (char *) msg, l);
181: len -= l;
182: }
1.1 deraadt 183:
1.12 markus 184: /* Get message type, and verify that we got a proper answer. */
185: buffer_get(&auth->identities, (char *) msg, 1);
186: if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER)
187: fatal("Bad authentication reply message type: %d", msg[0]);
188:
189: /* Get the number of entries in the response and check it for sanity. */
190: auth->howmany = buffer_get_int(&auth->identities);
191: if (auth->howmany > 1024)
192: fatal("Too many identities in authentication reply: %d\n", auth->howmany);
193:
194: /* Return the first entry (if any). */
195: return ssh_get_next_identity(auth, e, n, comment);
1.1 deraadt 196: }
197:
1.14 markus 198: /*
199: * Returns the next authentication identity for the agent. Other functions
200: * can be called between this and ssh_get_first_identity or two calls of this
201: * function. This returns 0 if there are no more identities. The caller
202: * must free comment after a successful return.
203: */
1.1 deraadt 204:
1.2 provos 205: int
206: ssh_get_next_identity(AuthenticationConnection *auth,
1.9 markus 207: BIGNUM *e, BIGNUM *n, char **comment)
1.1 deraadt 208: {
1.12 markus 209: unsigned int bits;
1.9 markus 210:
1.12 markus 211: /* Return failure if no more entries. */
212: if (auth->howmany <= 0)
213: return 0;
214:
1.14 markus 215: /*
216: * Get the next entry from the packet. These will abort with a fatal
217: * error if the packet is too short or contains corrupt data.
218: */
1.12 markus 219: bits = buffer_get_int(&auth->identities);
220: buffer_get_bignum(&auth->identities, e);
221: buffer_get_bignum(&auth->identities, n);
222: *comment = buffer_get_string(&auth->identities, NULL);
223:
224: if (bits != BN_num_bits(n))
1.19 markus 225: log("Warning: identity keysize mismatch: actual %d, announced %u",
226: BN_num_bits(n), bits);
1.9 markus 227:
1.12 markus 228: /* Decrement the number of remaining entries. */
229: auth->howmany--;
1.1 deraadt 230:
1.12 markus 231: return 1;
1.1 deraadt 232: }
233:
1.14 markus 234: /*
235: * Generates a random challenge, sends it to the agent, and waits for
236: * response from the agent. Returns true (non-zero) if the agent gave the
237: * correct answer, zero otherwise. Response type selects the style of
238: * response desired, with 0 corresponding to protocol version 1.0 (no longer
239: * supported) and 1 corresponding to protocol version 1.1.
240: */
1.1 deraadt 241:
1.2 provos 242: int
243: ssh_decrypt_challenge(AuthenticationConnection *auth,
1.12 markus 244: BIGNUM* e, BIGNUM *n, BIGNUM *challenge,
1.2 provos 245: unsigned char session_id[16],
246: unsigned int response_type,
247: unsigned char response[16])
1.1 deraadt 248: {
1.12 markus 249: Buffer buffer;
250: unsigned char buf[8192];
251: int len, l, i;
252:
253: /* Response type 0 is no longer supported. */
254: if (response_type == 0)
255: fatal("Compatibility with ssh protocol version 1.0 no longer supported.");
256:
257: /* Format a message to the agent. */
258: buf[0] = SSH_AGENTC_RSA_CHALLENGE;
259: buffer_init(&buffer);
260: buffer_append(&buffer, (char *) buf, 1);
261: buffer_put_int(&buffer, BN_num_bits(n));
262: buffer_put_bignum(&buffer, e);
263: buffer_put_bignum(&buffer, n);
264: buffer_put_bignum(&buffer, challenge);
265: buffer_append(&buffer, (char *) session_id, 16);
266: buffer_put_int(&buffer, response_type);
267:
268: /* Get the length of the message, and format it in the buffer. */
269: len = buffer_len(&buffer);
270: PUT_32BIT(buf, len);
271:
272: /* Send the length and then the packet to the agent. */
1.15 deraadt 273: if (atomicio(write, auth->fd, buf, 4) != 4 ||
274: atomicio(write, auth->fd, buffer_ptr(&buffer),
275: buffer_len(&buffer)) != buffer_len(&buffer)) {
1.12 markus 276: error("Error writing to authentication socket.");
277: error_cleanup:
278: buffer_free(&buffer);
279: return 0;
280: }
1.14 markus 281: /*
282: * Wait for response from the agent. First read the length of the
283: * response packet.
284: */
1.12 markus 285: len = 4;
286: while (len > 0) {
287: l = read(auth->fd, buf + 4 - len, len);
288: if (l <= 0) {
289: error("Error reading response length from authentication socket.");
290: goto error_cleanup;
291: }
292: len -= l;
293: }
294:
295: /* Extract the length, and check it for sanity. */
296: len = GET_32BIT(buf);
297: if (len > 256 * 1024)
298: fatal("Authentication response too long: %d", len);
299:
300: /* Read the rest of the response in tothe buffer. */
301: buffer_clear(&buffer);
302: while (len > 0) {
303: l = len;
304: if (l > sizeof(buf))
305: l = sizeof(buf);
306: l = read(auth->fd, buf, l);
307: if (l <= 0) {
308: error("Error reading response from authentication socket.");
309: goto error_cleanup;
310: }
311: buffer_append(&buffer, (char *) buf, l);
312: len -= l;
313: }
314:
315: /* Get the type of the packet. */
316: buffer_get(&buffer, (char *) buf, 1);
317:
318: /* Check for agent failure message. */
319: if (buf[0] == SSH_AGENT_FAILURE) {
320: log("Agent admitted failure to authenticate using the key.");
321: goto error_cleanup;
322: }
323: /* Now it must be an authentication response packet. */
324: if (buf[0] != SSH_AGENT_RSA_RESPONSE)
325: fatal("Bad authentication response: %d", buf[0]);
326:
1.14 markus 327: /*
328: * Get the response from the packet. This will abort with a fatal
329: * error if the packet is corrupt.
330: */
1.12 markus 331: for (i = 0; i < 16; i++)
332: response[i] = buffer_get_char(&buffer);
333:
334: /* The buffer containing the packet is no longer needed. */
335: buffer_free(&buffer);
336:
337: /* Correct answer. */
338: return 1;
339: }
1.1 deraadt 340:
1.22 markus 341: /* Encode key for a message to the agent. */
342:
343: void
344: ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment)
345: {
346: buffer_clear(b);
347: buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
348: buffer_put_int(b, BN_num_bits(key->n));
349: buffer_put_bignum(b, key->n);
350: buffer_put_bignum(b, key->e);
351: buffer_put_bignum(b, key->d);
352: /* To keep within the protocol: p < q for ssh. in SSL p > q */
353: buffer_put_bignum(b, key->iqmp); /* ssh key->u */
354: buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
355: buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
356: buffer_put_string(b, comment, strlen(comment));
357: }
358:
359: void
360: ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment)
361: {
362: buffer_clear(b);
363: buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
364: buffer_put_cstring(b, KEX_DSS);
365: buffer_put_bignum2(b, key->p);
366: buffer_put_bignum2(b, key->q);
367: buffer_put_bignum2(b, key->g);
368: buffer_put_bignum2(b, key->pub_key);
369: buffer_put_bignum2(b, key->priv_key);
370: buffer_put_string(b, comment, strlen(comment));
371: }
372:
1.14 markus 373: /*
374: * Adds an identity to the authentication server. This call is not meant to
375: * be used by normal applications.
376: */
1.1 deraadt 377:
1.18 markus 378: int
1.22 markus 379: ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
1.1 deraadt 380: {
1.12 markus 381: Buffer buffer;
382: unsigned char buf[8192];
1.21 markus 383: int len;
1.12 markus 384:
385: buffer_init(&buffer);
1.22 markus 386:
387: switch (key->type) {
388: case KEY_RSA:
389: ssh_encode_identity_rsa(&buffer, key->rsa, comment);
390: break;
391: case KEY_DSA:
392: ssh_encode_identity_dsa(&buffer, key->dsa, comment);
393: break;
394: default:
395: buffer_free(&buffer);
396: return 0;
397: break;
398: }
1.12 markus 399:
400: /* Get the length of the message, and format it in the buffer. */
401: len = buffer_len(&buffer);
402: PUT_32BIT(buf, len);
403:
404: /* Send the length and then the packet to the agent. */
1.15 deraadt 405: if (atomicio(write, auth->fd, buf, 4) != 4 ||
406: atomicio(write, auth->fd, buffer_ptr(&buffer),
407: buffer_len(&buffer)) != buffer_len(&buffer)) {
1.12 markus 408: error("Error writing to authentication socket.");
409: buffer_free(&buffer);
410: return 0;
411: }
1.21 markus 412: buffer_free(&buffer);
413: return ssh_agent_get_reply(auth);
1.12 markus 414: }
1.1 deraadt 415:
1.14 markus 416: /*
417: * Removes an identity from the authentication server. This call is not
418: * meant to be used by normal applications.
419: */
1.1 deraadt 420:
1.18 markus 421: int
1.12 markus 422: ssh_remove_identity(AuthenticationConnection *auth, RSA *key)
1.1 deraadt 423: {
1.12 markus 424: Buffer buffer;
1.21 markus 425: unsigned char buf[5];
426: int len;
1.12 markus 427:
428: /* Format a message to the agent. */
429: buffer_init(&buffer);
430: buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY);
431: buffer_put_int(&buffer, BN_num_bits(key->n));
432: buffer_put_bignum(&buffer, key->e);
433: buffer_put_bignum(&buffer, key->n);
434:
435: /* Get the length of the message, and format it in the buffer. */
436: len = buffer_len(&buffer);
437: PUT_32BIT(buf, len);
438:
439: /* Send the length and then the packet to the agent. */
1.15 deraadt 440: if (atomicio(write, auth->fd, buf, 4) != 4 ||
441: atomicio(write, auth->fd, buffer_ptr(&buffer),
442: buffer_len(&buffer)) != buffer_len(&buffer)) {
1.12 markus 443: error("Error writing to authentication socket.");
444: buffer_free(&buffer);
445: return 0;
446: }
1.21 markus 447: buffer_free(&buffer);
448: return ssh_agent_get_reply(auth);
1.12 markus 449: }
450:
1.14 markus 451: /*
452: * Removes all identities from the agent. This call is not meant to be used
453: * by normal applications.
454: */
1.1 deraadt 455:
1.18 markus 456: int
1.12 markus 457: ssh_remove_all_identities(AuthenticationConnection *auth)
1.1 deraadt 458: {
1.21 markus 459: unsigned char buf[5];
1.12 markus 460:
461: /* Get the length of the message, and format it in the buffer. */
462: PUT_32BIT(buf, 1);
463: buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES;
464:
465: /* Send the length and then the packet to the agent. */
1.15 deraadt 466: if (atomicio(write, auth->fd, buf, 5) != 5) {
1.12 markus 467: error("Error writing to authentication socket.");
468: return 0;
469: }
1.21 markus 470: return ssh_agent_get_reply(auth);
471: }
472:
473: /*
474: * Read for reply from agent. returns 1 for success, 0 on error
475: */
476:
477: int
478: ssh_agent_get_reply(AuthenticationConnection *auth)
479: {
480: Buffer buffer;
481: unsigned char buf[8192];
482: int len, l, type;
483:
1.14 markus 484: /*
485: * Wait for response from the agent. First read the length of the
486: * response packet.
487: */
1.12 markus 488: len = 4;
489: while (len > 0) {
490: l = read(auth->fd, buf + 4 - len, len);
491: if (l <= 0) {
492: error("Error reading response length from authentication socket.");
1.21 markus 493: buffer_free(&buffer);
1.12 markus 494: return 0;
495: }
496: len -= l;
497: }
498:
499: /* Extract the length, and check it for sanity. */
500: len = GET_32BIT(buf);
501: if (len > 256 * 1024)
1.21 markus 502: fatal("Response from agent too long: %d", len);
1.12 markus 503:
1.21 markus 504: /* Read the rest of the response in to the buffer. */
1.12 markus 505: buffer_init(&buffer);
506: while (len > 0) {
507: l = len;
508: if (l > sizeof(buf))
509: l = sizeof(buf);
510: l = read(auth->fd, buf, l);
511: if (l <= 0) {
512: error("Error reading response from authentication socket.");
513: buffer_free(&buffer);
514: return 0;
515: }
516: buffer_append(&buffer, (char *) buf, l);
517: len -= l;
518: }
519:
520: /* Get the type of the packet. */
521: type = buffer_get_char(&buffer);
1.21 markus 522: buffer_free(&buffer);
1.12 markus 523: switch (type) {
524: case SSH_AGENT_FAILURE:
1.22 markus 525: log("SSH_AGENT_FAILURE");
1.12 markus 526: return 0;
527: case SSH_AGENT_SUCCESS:
528: return 1;
529: default:
1.21 markus 530: fatal("Bad response from authentication agent: %d", type);
1.12 markus 531: }
532: /* NOTREACHED */
533: return 0;
534: }
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