2 * Copyright (c) 1991, 1993
3 * Dave Safford. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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9 * notice, this list of conditions and the following disclaimer.
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13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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29 * $FreeBSD: src/crypto/telnet/libtelnet/sra.c,v 1.1.2.7 2002/05/16 08:46:49 markm Exp $
34 #include <sys/types.h>
35 #include <arpa/telnet.h>
44 #include <security/pam_appl.h>
54 char pka[HEXKEYBYTES+1], ska[HEXKEYBYTES+1], pkb[HEXKEYBYTES+1];
55 char *user, *pass, *xuser, *xpass;
59 extern int auth_debug_mode;
62 static int sra_valid = 0;
63 static int passwd_sent = 0;
65 static unsigned char str_data[1024] = {
66 IAC, SB, TELOPT_AUTHENTICATION, 0, AUTHTYPE_SRA, };
69 #define XSMALL_LEN 513
73 #define SRA_CONTINUE 2
78 static int check_user(char *, const char *);
80 /* support routine to send out authentication message */
82 Data(Authenticator *ap, int type, void *d, int c)
84 unsigned char *p = str_data + 4;
85 unsigned char *cd = (unsigned char *)d;
88 c = strlen((char *)cd);
90 if (auth_debug_mode) {
91 printf("%s:%d: [%d] (%d)",
92 str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
102 if ((*p++ = *cd++) == IAC)
107 if (str_data[3] == TELQUAL_IS)
108 printsub('>', &str_data[2], p - (&str_data[2]));
109 return(net_write(str_data, p - str_data));
113 sra_init(Authenticator *ap __unused, int server)
116 str_data[3] = TELQUAL_REPLY;
118 str_data[3] = TELQUAL_IS;
120 user = malloc(SMALL_LEN);
121 xuser = malloc(XSMALL_LEN);
122 pass = malloc(SMALL_LEN);
123 xpass = malloc(XSMALL_LEN);
125 if (user == NULL || xuser == NULL || pass == NULL || xpass == NULL)
126 return 0; /* malloc failed */
134 /* client received a go-ahead for sra */
136 sra_send(Authenticator *ap)
141 printf("Sent PKA to server.\r\n" );
142 printf("Trying SRA secure login:\r\n");
143 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) {
145 printf("Not enough room for authentication data\r\n");
152 /* server received an IS -- could be SRA KEY, USER, or PASS */
154 sra_is(Authenticator *ap, unsigned char *data, int cnt)
164 if (cnt < HEXKEYBYTES) {
165 Data(ap, SRA_REJECT, (void *)0, 0);
166 auth_finished(ap, AUTH_USER);
168 printf("SRA user rejected for bad PKB\r\n");
172 printf("Sent pka\r\n");
173 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) {
175 printf("Not enough room\r\n");
178 memcpy(pkb, data, HEXKEYBYTES);
179 pkb[HEXKEYBYTES] = '\0';
180 common_key(ska, pkb, &ik, &ck);
185 if (cnt > XSMALL_LEN - 1) /* Attempted buffer overflow */
187 memcpy(xuser, data, cnt);
189 pk_decode(xuser, user, &ck);
190 auth_encrypt_user(user);
191 Data(ap, SRA_CONTINUE, (void *)0, 0);
195 if (cnt > XSMALL_LEN - 1) /* Attempted buffer overflow */
198 memcpy(xpass, data, cnt);
200 pk_decode(xpass, pass, &ck);
202 /* check user's password */
203 valid = check_user(user, pass);
206 Data(ap, SRA_ACCEPT, (void *)0, 0);
210 encrypt_session_key(&skey, 1);
213 auth_finished(ap, AUTH_VALID);
215 printf("SRA user accepted\r\n");
217 Data(ap, SRA_CONTINUE, (void *)0, 0);
219 Data(ap, SRA_REJECT, (void *)0, 0);
221 auth_finished(ap, AUTH_REJECT);
224 printf("SRA user failed\r\n");
230 printf("Unknown SRA option %d\r\n", data[-1]);
234 Data(ap, SRA_REJECT, 0, 0);
236 auth_finished(ap, AUTH_REJECT);
239 /* client received REPLY -- could be SRA KEY, CONTINUE, ACCEPT, or REJECT */
241 sra_reply(Authenticator *ap, unsigned char *data, int cnt)
243 char uprompt[SMALL_LEN], tuser[SMALL_LEN];
252 /* calculate common key */
253 if (cnt < HEXKEYBYTES) {
255 printf("SRA user rejected for bad PKB\r\n");
258 memcpy(pkb, data, HEXKEYBYTES);
259 pkb[HEXKEYBYTES] = '\0';
260 common_key(ska, pkb, &ik, &ck);
264 memset(tuser, 0, sizeof(tuser));
265 sprintf(uprompt, "User (%s): ", UserNameRequested);
266 if (telnet_gets(uprompt, tuser, SMALL_LEN-1, 1) == NULL) {
270 if (tuser[0] == '\n' || tuser[0] == '\r' ) {
271 strlcpy(user, UserNameRequested, SMALL_LEN);
273 /* telnet_gets leaves the newline on */
274 for (i = 0; i < sizeof(tuser); i++) {
275 if (tuser[i] == '\n') {
280 strlcpy(user, tuser, SMALL_LEN);
282 pk_encode(user, xuser, &ck);
286 printf("Sent KAB(U)\r\n");
287 if (!Data(ap, SRA_USER, xuser, strlen(xuser))) {
289 printf("Not enough room\r\n");
297 printf("[ SRA login failed ]\r\n");
300 /* encode password */
301 memset(pass, 0, SMALL_LEN);
302 if (telnet_gets("Password: ", pass, SMALL_LEN-1, 0) == NULL) {
306 pk_encode(pass, xpass, &ck);
309 printf("Sent KAB(P)\r\n");
310 if (!Data(ap, SRA_PASS, xpass, strlen(xpass))) {
312 printf("Not enough room\r\n");
319 printf("[ SRA refuses authentication ]\r\n");
320 printf("Trying plaintext login:\r\n");
321 auth_finished(0, AUTH_REJECT);
325 printf("[ SRA accepts you ]\r\n");
329 encrypt_session_key(&skey, 0);
330 auth_finished(ap, AUTH_VALID);
335 printf("Unknown SRA option %d\r\n", data[-1]);
341 sra_status(Authenticator *ap __unused, char *name, int level)
343 if (level < AUTH_USER)
345 if (UserNameRequested && sra_valid) {
346 strcpy(name, UserNameRequested);
353 #define BUMP(buf, len) while (*(buf)) { ++(buf), --(len); }
354 #define ADDC(buf, len, c) if ((len) > 0) { *(buf)++ = (c); --(len); }
357 sra_printsub(unsigned char *data, int cnt, unsigned char *ubuf, int buflen)
359 char lbuf[32], *buf = (char *)ubuf;
362 buf[buflen-1] = '\0'; /* make sure its NULL terminated */
367 strncpy(buf, " CONTINUE ", buflen);
370 case SRA_REJECT: /* Rejected (reason might follow) */
371 strncpy(buf, " REJECT ", buflen);
374 case SRA_ACCEPT: /* Accepted (name might follow) */
375 strncpy(buf, " ACCEPT ", buflen);
381 ADDC(buf, buflen, '"');
382 for (i = 4; i < cnt; i++)
383 ADDC(buf, buflen, data[i]);
384 ADDC(buf, buflen, '"');
385 ADDC(buf, buflen, '\0');
388 case SRA_KEY: /* Authentication data follows */
389 strncpy(buf, " KEY ", buflen);
393 strncpy(buf, " USER ", buflen);
397 strncpy(buf, " PASS ", buflen);
401 snprintf(lbuf, sizeof(lbuf), " %d (unknown)", data[3]);
402 strncpy(buf, lbuf, buflen);
406 for (i = 4; i < cnt; i++) {
407 snprintf(lbuf, sizeof(lbuf), " %d", data[i]);
408 strncpy(buf, lbuf, buflen);
418 isroot(const char *usr)
420 struct passwd pws, *pwd;
423 if (getpwnam_r(usr, &pws, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
427 return (!pwd->pw_uid);
431 rootterm(const char *ttyn)
435 return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE);
439 check_user(char *name, const char *cred)
441 struct passwd pws, *pw;
443 char *xpasswd, *salt;
445 if (isroot(name) && !rootterm(line)) {
446 crypt("AA", "*"); /* Waste some time to simulate success */
450 if (getpwnam_r(name, &pws, pwbuf, sizeof(pwbuf), &pw) == 0 &&
452 if (pw->pw_shell == NULL)
455 salt = pw->pw_passwd;
456 xpasswd = crypt(cred, salt);
457 /* The strcmp does not catch null passwords! */
458 if (*pw->pw_passwd == '\0' || strcmp(xpasswd, pw->pw_passwd))
469 * The following is stolen from ftpd, which stole it from the imap-uw
470 * PAM module and login.c. It is needed because we can't really
471 * "converse" with the user, having already gone to the trouble of
472 * getting their username and password through an encrypted channel.
475 #define COPY_STRING(s) (s ? strdup(s) : NULL)
481 typedef struct cred_t cred_t;
484 auth_conv(int num_msg, const struct pam_message **msg,
485 struct pam_response **resp, void *appdata)
488 cred_t *cred = appdata;
489 struct pam_response *reply = malloc(sizeof(*reply) * num_msg);
494 for (i = 0; i < num_msg; i++) {
495 switch (msg[i]->msg_style) {
496 case PAM_PROMPT_ECHO_ON: /* assume want user name */
497 reply[i].resp_retcode = PAM_SUCCESS;
498 reply[i].resp = COPY_STRING(cred->uname);
499 /* PAM frees resp. */
501 case PAM_PROMPT_ECHO_OFF: /* assume want password */
502 reply[i].resp_retcode = PAM_SUCCESS;
503 reply[i].resp = COPY_STRING(cred->pass);
504 /* PAM frees resp. */
508 reply[i].resp_retcode = PAM_SUCCESS;
509 reply[i].resp = NULL;
511 default: /* unknown message style */
522 * The PAM version as a side effect may put a new username in *name.
525 check_user(char *name, const char *cred)
527 pam_handle_t *pamh = NULL;
531 cred_t auth_cred = { name, cred };
532 struct pam_conv conv = { &auth_conv, &auth_cred };
534 e = pam_start("telnetd", name, &conv, &pamh);
535 if (e != PAM_SUCCESS) {
536 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, e));
540 #if 0 /* Where can we find this value? */
541 e = pam_set_item(pamh, PAM_RHOST, remotehost);
542 if (e != PAM_SUCCESS) {
543 syslog(LOG_ERR, "pam_set_item(PAM_RHOST): %s",
544 pam_strerror(pamh, e));
549 e = pam_authenticate(pamh, 0);
553 * With PAM we support the concept of a "template"
554 * user. The user enters a login name which is
555 * authenticated by PAM, usually via a remote service
556 * such as RADIUS or TACACS+. If authentication
557 * succeeds, a different but related "template" name
558 * is used for setting the credentials, shell, and
559 * home directory. The name the user enters need only
560 * exist on the remote authentication server, but the
561 * template name must be present in the local password
564 * This is supported by two various mechanisms in the
565 * individual modules. However, from the application's
566 * point of view, the template user is always passed
567 * back as a changed value of the PAM_USER item.
569 if ((e = pam_get_item(pamh, PAM_USER,
570 &item)) == PAM_SUCCESS)
571 strlcpy(name, item, SMALL_LEN);
573 syslog(LOG_ERR, "Couldn't get PAM_USER: %s",
574 pam_strerror(pamh, e));
577 #if 0 /* pam_securetty(8) should be used to enforce this */
578 if (isroot(name) && !rootterm(line))
584 case PAM_USER_UNKNOWN:
590 syslog(LOG_ERR, "auth_pam: %s", pam_strerror(pamh, e));
595 if ((e = pam_end(pamh, e)) != PAM_SUCCESS) {
596 syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, e));
604 #endif /* ENCRYPTION */