crypto/telnet/libtelnet/sra.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      Dave Safford.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  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.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *
  30  * $FreeBSD: src/crypto/telnet/libtelnet/sra.c,v 1.1.2.7 2002/05/16 08:46:49 markm Exp $
  31  * $DragonFly: src/crypto/telnet/libtelnet/sra.c,v 1.3 2006/01/17 23:50:34 dillon Exp $
  32  */
  33
  34 #ifdef  SRA
  35 #ifdef  ENCRYPTION
  36 #include <sys/types.h>
  37 #include <arpa/telnet.h>
  38 #include <pwd.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <syslog.h>
  43 #include <ttyent.h>
  44
  45 #ifndef NOPAM
  46 #include <security/pam_appl.h>
  47 #else
  48 #include <unistd.h>
  49 #endif
  50
  51 #include "auth.h"
  52 #include "misc.h"
  53 #include "encrypt.h"
  54 #include "pk.h"
  55
  56 char pka[HEXKEYBYTES+1], ska[HEXKEYBYTES+1], pkb[HEXKEYBYTES+1];
  57 char *user, *pass, *xuser, *xpass;
  58 DesData ck;
  59 IdeaData ik;
  60
  61 #define PASS_SIZE       256
  62
  63 extern int auth_debug_mode;
  64 extern char line[];
  65
  66 static int sra_valid = 0;
  67 static int passwd_sent = 0;
  68
  69 static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0,
  70                                         AUTHTYPE_SRA, };
  71
  72 #define SRA_KEY 0
  73 #define SRA_USER 1
  74 #define SRA_CONTINUE 2
  75 #define SRA_PASS 3
  76 #define SRA_ACCEPT 4
  77 #define SRA_REJECT 5
  78
  79 static int check_user(char *, char *);
  80
  81 /* support routine to send out authentication message */
  82 static int
  83 Data(Authenticator *ap, int type, void *d, int c)
  84 {
  85         unsigned char *p = str_data + 4;
  86         unsigned char *cd = (unsigned char *)d;
  87
  88         if (c == -1)
  89                 c = strlen((char *)cd);
  90
  91         if (auth_debug_mode) {
  92                 printf("%s:%d: [%d] (%d)",
  93                         str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
  94                         str_data[3],
  95                         type, c);
  96                 printd(d, c);
  97                 printf("\r\n");
  98         }
  99         *p++ = ap->type;
 100         *p++ = ap->way;
 101         *p++ = type;
 102         while (c-- > 0) {
 103                 if ((*p++ = *cd++) == IAC)
 104                         *p++ = IAC;
 105         }
 106         *p++ = IAC;
 107         *p++ = SE;
 108         if (str_data[3] == TELQUAL_IS)
 109                 printsub('>', &str_data[2], p - (&str_data[2]));
 110         return(net_write(str_data, p - str_data));
 111 }
 112
 113 int
 114 sra_init(Authenticator *ap __unused, int server)
 115 {
 116         if (server)
 117                 str_data[3] = TELQUAL_REPLY;
 118         else
 119                 str_data[3] = TELQUAL_IS;
 120
 121         user = (char *)malloc(256);
 122         xuser = (char *)malloc(513);
 123         pass = (char *)malloc(PASS_SIZE);
 124         xpass = (char *)malloc(513);
 125
 126         if (user == NULL || xuser == NULL || pass == NULL || xpass ==
 127         NULL)
 128                 return 0; /* malloc failed */
 129
 130         passwd_sent = 0;
 131
 132         genkeys(pka,ska);
 133         return(1);
 134 }
 135
 136 /* client received a go-ahead for sra */
 137 int
 138 sra_send(Authenticator *ap)
 139 {
 140         /* send PKA */
 141
 142         if (auth_debug_mode)
 143                 printf("Sent PKA to server.\r\n" );
 144         printf("Trying SRA secure login:\r\n");
 145         if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) {
 146                 if (auth_debug_mode)
 147                         printf("Not enough room for authentication data\r\n");
 148                 return(0);
 149         }
 150
 151         return(1);
 152 }
 153
 154 /* server received an IS -- could be SRA KEY, USER, or PASS */
 155 void
 156 sra_is(Authenticator *ap, unsigned char *data, int cnt)
 157 {
 158         int valid;
 159         Session_Key skey;
 160
 161         if (cnt-- < 1)
 162                 goto bad;
 163         switch (*data++) {
 164
 165         case SRA_KEY:
 166                 if (cnt < HEXKEYBYTES) {
 167                         Data(ap, SRA_REJECT, (void *)0, 0);
 168                         auth_finished(ap, AUTH_USER);
 169                         if (auth_debug_mode) {
 170                                 printf("SRA user rejected for bad PKB\r\n");
 171                         }
 172                         return;
 173                 }
 174                 if (auth_debug_mode)
 175                         printf("Sent pka\r\n");
 176                 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) {
 177                         if (auth_debug_mode)
 178                                 printf("Not enough room\r\n");
 179                         return;
 180                 }
 181                 memcpy(pkb,data,HEXKEYBYTES);
 182                 pkb[HEXKEYBYTES] = '\0';
 183                 common_key(ska,pkb,&ik,&ck);
 184                 return;
 185
 186         case SRA_USER:
 187                 /* decode KAB(u) */
 188                 if (cnt > 512) /* Attempted buffer overflow */
 189                         break;
 190                 memcpy(xuser,data,cnt);
 191                 xuser[cnt] = '\0';
 192                 pk_decode(xuser,user,&ck);
 193                 auth_encrypt_user(user);
 194                 Data(ap, SRA_CONTINUE, (void *)0, 0);
 195
 196                 return;
 197
 198         case SRA_PASS:
 199                 if (cnt > 512) /* Attempted buffer overflow */
 200                         break;
 201                 /* decode KAB(P) */
 202                 memcpy(xpass,data,cnt);
 203                 xpass[cnt] = '\0';
 204                 pk_decode(xpass,pass,&ck);
 205
 206                 /* check user's password */
 207                 valid = check_user(user,pass);
 208
 209                 if(valid) {
 210                         Data(ap, SRA_ACCEPT, (void *)0, 0);
 211                         skey.data = ck;
 212                         skey.type = SK_DES;
 213                         skey.length = 8;
 214                         encrypt_session_key(&skey, 1);
 215
 216                         sra_valid = 1;
 217                         auth_finished(ap, AUTH_VALID);
 218                         if (auth_debug_mode) {
 219                                 printf("SRA user accepted\r\n");
 220                         }
 221                 }
 222                 else {
 223                         Data(ap, SRA_CONTINUE, (void *)0, 0);
 224 /*
 225                         Data(ap, SRA_REJECT, (void *)0, 0);
 226                         sra_valid = 0;
 227                         auth_finished(ap, AUTH_REJECT);
 228 */
 229                         if (auth_debug_mode) {
 230                                 printf("SRA user failed\r\n");
 231                         }
 232                 }
 233                 return;
 234
 235         default:
 236                 if (auth_debug_mode)
 237                         printf("Unknown SRA option %d\r\n", data[-1]);
 238         }
 239 bad:
 240         Data(ap, SRA_REJECT, 0, 0);
 241         sra_valid = 0;
 242         auth_finished(ap, AUTH_REJECT);
 243 }
 244
 245 /* client received REPLY -- could be SRA KEY, CONTINUE, ACCEPT, or REJECT */
 246 void
 247 sra_reply(Authenticator *ap, unsigned char *data, int cnt)
 248 {
 249         char uprompt[256],tuser[256];
 250         Session_Key skey;
 251         size_t i;
 252
 253         if (cnt-- < 1)
 254                 return;
 255         switch (*data++) {
 256
 257         case SRA_KEY:
 258                 /* calculate common key */
 259                 if (cnt < HEXKEYBYTES) {
 260                         if (auth_debug_mode) {
 261                                 printf("SRA user rejected for bad PKB\r\n");
 262                         }
 263                         return;
 264                 }
 265                 memcpy(pkb,data,HEXKEYBYTES);
 266                 pkb[HEXKEYBYTES] = '\0';
 267
 268                 common_key(ska,pkb,&ik,&ck);
 269
 270         enc_user:
 271
 272                 /* encode user */
 273                 memset(tuser,0,sizeof(tuser));
 274                 sprintf(uprompt,"User (%s): ",UserNameRequested);
 275                 telnet_gets(uprompt,tuser,255,1);
 276                 if (tuser[0] == '\n' || tuser[0] == '\r' )
 277                         strcpy(user,UserNameRequested);
 278                 else {
 279                         /* telnet_gets leaves the newline on */
 280                         for(i=0;i<sizeof(tuser);i++) {
 281                                 if (tuser[i] == '\n') {
 282                                         tuser[i] = '\0';
 283                                         break;
 284                                 }
 285                         }
 286                         strcpy(user,tuser);
 287                 }
 288                 pk_encode(user,xuser,&ck);
 289
 290                 /* send it off */
 291                 if (auth_debug_mode)
 292                         printf("Sent KAB(U)\r\n");
 293                 if (!Data(ap, SRA_USER, (void *)xuser, strlen(xuser))) {
 294                         if (auth_debug_mode)
 295                                 printf("Not enough room\r\n");
 296                         return;
 297                 }
 298                 break;
 299
 300         case SRA_CONTINUE:
 301                 if (passwd_sent) {
 302                         passwd_sent = 0;
 303                         printf("[ SRA login failed ]\r\n");
 304                         goto enc_user;
 305                 }
 306                 /* encode password */
 307                 memset(pass,0,PASS_SIZE);
 308                 telnet_gets("Password: ",pass,PASS_SIZE-1,0);
 309                 pk_encode(pass,xpass,&ck);
 310                 /* send it off */
 311                 if (auth_debug_mode)
 312                         printf("Sent KAB(P)\r\n");
 313                 if (!Data(ap, SRA_PASS, (void *)xpass, strlen(xpass))) {
 314                         if (auth_debug_mode)
 315                                 printf("Not enough room\r\n");
 316                         return;
 317                 }
 318                 passwd_sent = 1;
 319                 break;
 320
 321         case SRA_REJECT:
 322                 printf("[ SRA refuses authentication ]\r\n");
 323                 printf("Trying plaintext login:\r\n");
 324                 auth_finished(0,AUTH_REJECT);
 325                 return;
 326
 327         case SRA_ACCEPT:
 328                 printf("[ SRA accepts you ]\r\n");
 329                 skey.data = ck;
 330                 skey.type = SK_DES;
 331                 skey.length = 8;
 332                 encrypt_session_key(&skey, 0);
 333
 334                 auth_finished(ap, AUTH_VALID);
 335                 return;
 336         default:
 337                 if (auth_debug_mode)
 338                         printf("Unknown SRA option %d\r\n", data[-1]);
 339                 return;
 340         }
 341 }
 342
 343 int
 344 sra_status(Authenticator *ap __unused, char *name, int level)
 345 {
 346         if (level < AUTH_USER)
 347                 return(level);
 348         if (UserNameRequested && sra_valid) {
 349                 strcpy(name, UserNameRequested);
 350                 return(AUTH_VALID);
 351         } else
 352                 return(AUTH_USER);
 353 }
 354
 355 #define BUMP(buf, len)          while (*(buf)) {++(buf), --(len);}
 356 #define ADDC(buf, len, c)       if ((len) > 0) {*(buf)++ = (c); --(len);}
 357
 358 void
 359 sra_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
 360 {
 361         char lbuf[32];
 362         int i;
 363
 364         buf[buflen-1] = '\0';           /* make sure its NULL terminated */
 365         buflen -= 1;
 366
 367         switch(data[3]) {
 368
 369         case SRA_CONTINUE:
 370                 strncpy((char *)buf, " CONTINUE ", buflen);
 371                 goto common;
 372
 373         case SRA_REJECT:                /* Rejected (reason might follow) */
 374                 strncpy((char *)buf, " REJECT ", buflen);
 375                 goto common;
 376
 377         case SRA_ACCEPT:                /* Accepted (name might follow) */
 378                 strncpy((char *)buf, " ACCEPT ", buflen);
 379
 380         common:
 381                 BUMP(buf, buflen);
 382                 if (cnt <= 4)
 383                         break;
 384                 ADDC(buf, buflen, '"');
 385                 for (i = 4; i < cnt; i++)
 386                         ADDC(buf, buflen, data[i]);
 387                 ADDC(buf, buflen, '"');
 388                 ADDC(buf, buflen, '\0');
 389                 break;
 390
 391         case SRA_KEY:                   /* Authentication data follows */
 392                 strncpy((char *)buf, " KEY ", buflen);
 393                 goto common2;
 394
 395         case SRA_USER:
 396                 strncpy((char *)buf, " USER ", buflen);
 397                 goto common2;
 398
 399         case SRA_PASS:
 400                 strncpy((char *)buf, " PASS ", buflen);
 401                 goto common2;
 402
 403         default:
 404                 sprintf(lbuf, " %d (unknown)", data[3]);
 405                 strncpy((char *)buf, lbuf, buflen);
 406         common2:
 407                 BUMP(buf, buflen);
 408                 for (i = 4; i < cnt; i++) {
 409                         sprintf(lbuf, " %d", data[i]);
 410                         strncpy((char *)buf, lbuf, buflen);
 411                         BUMP(buf, buflen);
 412                 }
 413                 break;
 414         }
 415 }
 416
 417 static int
 418 isroot(const char *usr)
 419 {
 420         struct passwd *pwd;
 421
 422         if ((pwd=getpwnam(usr))==NULL)
 423                 return 0;
 424         return (!pwd->pw_uid);
 425 }
 426
 427 static int
 428 rootterm(char *ttyn)
 429 {
 430         struct ttyent *t;
 431
 432         return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE);
 433 }
 434
 435 #ifdef NOPAM
 436 static int
 437 check_user(char *name, char *cred)
 438 {
 439         char *cp;
 440         char *xpasswd, *salt;
 441
 442         if (isroot(name) && !rootterm(line))
 443         {
 444                 crypt("AA","*"); /* Waste some time to simulate success */
 445                 return(0);
 446         }
 447
 448         if (pw = sgetpwnam(name)) {
 449                 if (pw->pw_shell == NULL) {
 450                         pw = (struct passwd *) NULL;
 451                         return(0);
 452                 }
 453
 454                 salt = pw->pw_passwd;
 455                 xpasswd = crypt(cred, salt);
 456                 /* The strcmp does not catch null passwords! */
 457                 if (pw == NULL || *pw->pw_passwd == '\0' ||
 458                         strcmp(xpasswd, pw->pw_passwd)) {
 459                         pw = (struct passwd *) NULL;
 460                         return(0);
 461                 }
 462                 return(1);
 463         }
 464         return(0);
 465 }
 466 #else
 467
 468 /*
 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.
 473  */
 474
 475 #define COPY_STRING(s) (s ? strdup(s):NULL)
 476
 477 struct cred_t {
 478         const char *uname;
 479         const char *pass;
 480 };
 481 typedef struct cred_t cred_t;
 482
 483 static int
 484 auth_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata)
 485 {
 486         int i;
 487         cred_t *cred = (cred_t *) appdata;
 488         struct pam_response *reply =
 489                 malloc(sizeof(struct pam_response) * num_msg);
 490
 491         if (reply == NULL)
 492                 return PAM_BUF_ERR;
 493
 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. */
 500                         break;
 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. */
 505                         break;
 506                 case PAM_TEXT_INFO:
 507                 case PAM_ERROR_MSG:
 508                         reply[i].resp_retcode = PAM_SUCCESS;
 509                         reply[i].resp = NULL;
 510                         break;
 511                 default:                        /* unknown message style */
 512                         free(reply);
 513                         return PAM_CONV_ERR;
 514                 }
 515         }
 516
 517         *resp = reply;
 518         return PAM_SUCCESS;
 519 }
 520
 521 /*
 522  * The PAM version as a side effect may put a new username in *name.
 523  */
 524 static int
 525 check_user(char *name, char *cred)
 526 {
 527         pam_handle_t *pamh = NULL;
 528         const void *item;
 529         int rval;
 530         int e;
 531         cred_t auth_cred = { name, cred };
 532         struct pam_conv conv = { &auth_conv, &auth_cred };
 533
 534         e = pam_start("telnetd", name, &conv, &pamh);
 535         if (e != PAM_SUCCESS) {
 536                 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, e));
 537                 return 0;
 538         }
 539
 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));
 545                 return 0;
 546         }
 547 #endif
 548
 549         e = pam_authenticate(pamh, 0);
 550         switch (e) {
 551         case PAM_SUCCESS:
 552                 /*
 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
 562                  * database.
 563                  *
 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.
 568                  */
 569                 if ((e = pam_get_item(pamh, PAM_USER, &item)) ==
 570                     PAM_SUCCESS) {
 571                         strcpy(name, item);
 572                 } else
 573                         syslog(LOG_ERR, "Couldn't get PAM_USER: %s",
 574                         pam_strerror(pamh, e));
 575                 if (isroot(name) && !rootterm(line))
 576                         rval = 0;
 577                 else
 578                         rval = 1;
 579                 break;
 580
 581         case PAM_AUTH_ERR:
 582         case PAM_USER_UNKNOWN:
 583         case PAM_MAXTRIES:
 584                 rval = 0;
 585         break;
 586
 587         default:
 588                 syslog(LOG_ERR, "auth_pam: %s", pam_strerror(pamh, e));
 589                 rval = 0;
 590                 break;
 591         }
 592
 593         if ((e = pam_end(pamh, e)) != PAM_SUCCESS) {
 594                 syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, e));
 595                 rval = 0;
 596         }
 597         return rval;
 598 }
 599
 600 #endif
 601
 602 #endif /* ENCRYPTION */
 603 #endif /* SRA */