Annotation of src/usr.bin/ssh/authfd.c, Revision 1.26
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"
1.26 ! markus 20: RCSID("$OpenBSD: authfd.c,v 1.25 2000/08/19 21:34:42 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);
1.26 ! markus 358: buffer_put_int(&msg, 0); /* flags, unused */
1.25 markus 359: xfree(blob);
360:
361: if (ssh_request_reply(auth, &msg, &msg) == 0) {
362: buffer_free(&msg);
363: return -1;
364: }
365: type = buffer_get_char(&msg);
366: if (type == SSH_AGENT_FAILURE) {
367: log("Agent admitted failure to sign using the key.");
368: } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
369: fatal("Bad authentication response: %d", type);
370: } else {
371: ret = 0;
372: *sigp = buffer_get_string(&msg, lenp);
373: }
374: buffer_free(&msg);
375: return ret;
376: }
377:
1.22 markus 378: /* Encode key for a message to the agent. */
379:
380: void
381: ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment)
382: {
383: buffer_clear(b);
384: buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
385: buffer_put_int(b, BN_num_bits(key->n));
386: buffer_put_bignum(b, key->n);
387: buffer_put_bignum(b, key->e);
388: buffer_put_bignum(b, key->d);
389: /* To keep within the protocol: p < q for ssh. in SSL p > q */
390: buffer_put_bignum(b, key->iqmp); /* ssh key->u */
391: buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
392: buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
393: buffer_put_string(b, comment, strlen(comment));
394: }
395:
396: void
397: ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment)
398: {
399: buffer_clear(b);
400: buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
401: buffer_put_cstring(b, KEX_DSS);
402: buffer_put_bignum2(b, key->p);
403: buffer_put_bignum2(b, key->q);
404: buffer_put_bignum2(b, key->g);
405: buffer_put_bignum2(b, key->pub_key);
406: buffer_put_bignum2(b, key->priv_key);
407: buffer_put_string(b, comment, strlen(comment));
408: }
409:
1.14 markus 410: /*
411: * Adds an identity to the authentication server. This call is not meant to
412: * be used by normal applications.
413: */
1.1 deraadt 414:
1.18 markus 415: int
1.22 markus 416: ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
1.1 deraadt 417: {
1.25 markus 418: Buffer msg;
1.24 markus 419: int type;
1.12 markus 420:
1.25 markus 421: buffer_init(&msg);
1.22 markus 422:
423: switch (key->type) {
424: case KEY_RSA:
1.25 markus 425: ssh_encode_identity_rsa(&msg, key->rsa, comment);
1.22 markus 426: break;
427: case KEY_DSA:
1.25 markus 428: ssh_encode_identity_dsa(&msg, key->dsa, comment);
1.22 markus 429: break;
430: default:
1.25 markus 431: buffer_free(&msg);
1.22 markus 432: return 0;
433: break;
434: }
1.25 markus 435: if (ssh_request_reply(auth, &msg, &msg) == 0) {
436: buffer_free(&msg);
1.12 markus 437: return 0;
438: }
1.25 markus 439: type = buffer_get_char(&msg);
440: buffer_free(&msg);
1.24 markus 441: return decode_reply(type);
1.12 markus 442: }
1.1 deraadt 443:
1.14 markus 444: /*
445: * Removes an identity from the authentication server. This call is not
446: * meant to be used by normal applications.
447: */
1.1 deraadt 448:
1.18 markus 449: int
1.25 markus 450: ssh_remove_identity(AuthenticationConnection *auth, Key *key)
1.1 deraadt 451: {
1.25 markus 452: Buffer msg;
1.24 markus 453: int type;
1.25 markus 454: unsigned char *blob;
455: unsigned int blen;
1.12 markus 456:
1.25 markus 457: buffer_init(&msg);
1.12 markus 458:
1.25 markus 459: if (key->type == KEY_RSA) {
460: buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
461: buffer_put_int(&msg, BN_num_bits(key->rsa->n));
462: buffer_put_bignum(&msg, key->rsa->e);
463: buffer_put_bignum(&msg, key->rsa->n);
464: } else if (key->type == KEY_DSA) {
465: dsa_make_key_blob(key, &blob, &blen);
466: buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
467: buffer_put_string(&msg, blob, blen);
468: xfree(blob);
469: } else {
470: buffer_free(&msg);
471: return 0;
472: }
473: if (ssh_request_reply(auth, &msg, &msg) == 0) {
474: buffer_free(&msg);
1.12 markus 475: return 0;
476: }
1.25 markus 477: type = buffer_get_char(&msg);
478: buffer_free(&msg);
1.24 markus 479: return decode_reply(type);
1.12 markus 480: }
481:
1.14 markus 482: /*
483: * Removes all identities from the agent. This call is not meant to be used
484: * by normal applications.
485: */
1.1 deraadt 486:
1.18 markus 487: int
1.25 markus 488: ssh_remove_all_identities(AuthenticationConnection *auth, int version)
1.1 deraadt 489: {
1.25 markus 490: Buffer msg;
1.24 markus 491: int type;
1.25 markus 492: int code = (version==1) ?
493: SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
494: SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
1.12 markus 495:
1.25 markus 496: buffer_init(&msg);
497: buffer_put_char(&msg, code);
1.12 markus 498:
1.25 markus 499: if (ssh_request_reply(auth, &msg, &msg) == 0) {
500: buffer_free(&msg);
1.12 markus 501: return 0;
502: }
1.25 markus 503: type = buffer_get_char(&msg);
504: buffer_free(&msg);
1.24 markus 505: return decode_reply(type);
1.21 markus 506: }
507:
508: int
1.24 markus 509: decode_reply(int type)
1.21 markus 510: {
1.12 markus 511: switch (type) {
512: case SSH_AGENT_FAILURE:
1.24 markus 513: log("SSH_AGENT_FAILURE");
1.12 markus 514: return 0;
515: case SSH_AGENT_SUCCESS:
516: return 1;
517: default:
1.21 markus 518: fatal("Bad response from authentication agent: %d", type);
1.12 markus 519: }
520: /* NOTREACHED */
521: return 0;
522: }
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