pppd/plugins/winbind.c

   1 /***********************************************************************
   2 *
   3 * winbind.c
   4 *
   5 * WINBIND plugin for pppd.  Performs PAP, CHAP, MS-CHAP, MS-CHAPv2
   6 * authentication using WINBIND to contact a NT-style PDC.
   7 *
   8 * Based on the structure of the radius module.
   9 *
  10 * Copyright (C) 2003 Andrew Bartlet <abartlet@samba.org>
  11 *
  12 * Copyright 1999 Paul Mackerras, Alan Curry.
  13 * (pipe read code from passpromt.c)
  14 *
  15 * Copyright (C) 2002 Roaring Penguin Software Inc.
  16 *
  17 * Based on a patch for ipppd, which is:
  18 *    Copyright (C) 1996, Matjaz Godec <gody@elgo.si>
  19 *    Copyright (C) 1996, Lars Fenneberg <in5y050@public.uni-hamburg.de>
  20 *    Copyright (C) 1997, Miguel A.L. Paraz <map@iphil.net>
  21 *
  22 * Uses radiusclient library, which is:
  23 *    Copyright (C) 1995,1996,1997,1998 Lars Fenneberg <lf@elemental.net>
  24 *    Copyright (C) 2002 Roaring Penguin Software Inc.
  25 *
  26 * MPPE support is by Ralf Hofmann, <ralf.hofmann@elvido.net>, with
  27 * modification from Frank Cusack, <frank@google.com>.
  28 *
  29 * Updated on 2003-12-12 to support updated PPP plugin API from latest CVS
  30 *    Copyright (C) 2003, Sean E. Millichamp <sean at bruenor dot org>
  31 *
  32 * This plugin may be distributed according to the terms of the GNU
  33 * General Public License, version 2 or (at your option) any later version.
  34 *
  35 ***********************************************************************/
  36
  37 #include "pppd.h"
  38 #include "chap-new.h"
  39 #include "chap_ms.h"
  40 #ifdef MPPE
  41 #include "md5.h"
  42 #endif
  43 #include "fsm.h"
  44 #include "ipcp.h"
  45 #include <syslog.h>
  46 #include <sys/types.h>
  47 #include <sys/stat.h>
  48 #include <fcntl.h>
  49 #include <sys/time.h>
  50 #include <sys/wait.h>
  51 #include <string.h>
  52 #include <unistd.h>
  53 #include <stdlib.h>
  54 #include <errno.h>
  55 #include <ctype.h>
  56
  57 #define BUF_LEN 1024
  58
  59 #define NOT_AUTHENTICATED 0
  60 #define AUTHENTICATED 1
  61
  62 static char *ntlm_auth = NULL;
  63
  64 static int set_ntlm_auth(char **argv)
  65 {
  66         char *p;
  67
  68         p = argv[0];
  69         if (p[0] != '/') {
  70                 option_error("ntlm_auth-helper argument must be full path");
  71                 return 0;
  72         }
  73         p = strdup(p);
  74         if (p == NULL) {
  75                 novm("ntlm_auth-helper argument");
  76                 return 0;
  77         }
  78         if (ntlm_auth != NULL)
  79                 free(ntlm_auth);
  80         ntlm_auth = p;
  81         return 1;
  82 }
  83
  84 static option_t Options[] = {
  85         { "ntlm_auth-helper", o_special, (void *) &set_ntlm_auth,
  86           "Path to ntlm_auth executable", OPT_PRIV },
  87         { NULL }
  88 };
  89
  90 static int
  91 winbind_secret_check(void);
  92
  93 static int winbind_pap_auth(char *user,
  94                            char *passwd,
  95                            char **msgp,
  96                            struct wordlist **paddrs,
  97                            struct wordlist **popts);
  98 static int winbind_chap_verify(char *user, char *ourname, int id,
  99                                struct chap_digest_type *digest,
 100                                unsigned char *challenge,
 101                                unsigned char *response,
 102                                char *message, int message_space);
 103 static int winbind_allowed_address(u_int32_t addr);
 104
 105 char pppd_version[] = VERSION;
 106
 107 /**********************************************************************
 108 * %FUNCTION: plugin_init
 109 * %ARGUMENTS:
 110 *  None
 111 * %RETURNS:
 112 *  Nothing
 113 * %DESCRIPTION:
 114 *  Initializes WINBIND plugin.
 115 ***********************************************************************/
 116 void
 117 plugin_init(void)
 118 {
 119     pap_check_hook = winbind_secret_check;
 120     pap_auth_hook = winbind_pap_auth;
 121
 122     chap_check_hook = winbind_secret_check;
 123     chap_verify_hook = winbind_chap_verify;
 124
 125     allowed_address_hook = winbind_allowed_address;
 126
 127     /* Don't ask the peer for anything other than MS-CHAP or MS-CHAP V2 */
 128     chap_mdtype_all &= (MDTYPE_MICROSOFT_V2 | MDTYPE_MICROSOFT);
 129
 130     add_options(Options);
 131
 132     info("WINBIND plugin initialized.");
 133 }
 134
 135 /**
 136  Routine to get hex characters and turn them into a 16 byte array.
 137  the array can be variable length, and any non-hex-numeric
 138  characters are skipped.  "0xnn" or "0Xnn" is specially catered
 139  for.
 140
 141  valid examples: "0A5D15"; "0x15, 0x49, 0xa2"; "59\ta9\te3\n"
 142
 143 **/
 144
 145 /*
 146    Unix SMB/CIFS implementation.
 147    Samba utility functions
 148
 149    Copyright (C) Andrew Tridgell 1992-2001
 150    Copyright (C) Simo Sorce      2001-2002
 151    Copyright (C) Martin Pool     2003
 152
 153    This program is free software; you can redistribute it and/or modify
 154    it under the terms of the GNU General Public License as published by
 155    the Free Software Foundation; either version 2 of the License, or
 156    (at your option) any later version.
 157
 158    This program is distributed in the hope that it will be useful,
 159    but WITHOUT ANY WARRANTY; without even the implied warranty of
 160    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 161    GNU General Public License for more details.
 162
 163    You should have received a copy of the GNU General Public License
 164    along with this program; if not, write to the Free Software
 165    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 166 */
 167
 168 size_t strhex_to_str(char *p, size_t len, const char *strhex)
 169 {
 170         size_t i;
 171         size_t num_chars = 0;
 172         unsigned char   lonybble, hinybble;
 173         const char     *hexchars = "0123456789ABCDEF";
 174         char           *p1 = NULL, *p2 = NULL;
 175
 176         for (i = 0; i < len && strhex[i] != 0; i++) {
 177                 if (strncmp(hexchars, "0x", 2) == 0) {
 178                         i++; /* skip two chars */
 179                         continue;
 180                 }
 181
 182                 if (!(p1 = strchr(hexchars, toupper(strhex[i]))))
 183                         break;
 184
 185                 i++; /* next hex digit */
 186
 187                 if (!(p2 = strchr(hexchars, toupper(strhex[i]))))
 188                         break;
 189
 190                 /* get the two nybbles */
 191                 hinybble = (p1 - hexchars);
 192                 lonybble = (p2 - hexchars);
 193
 194                 p[num_chars] = (hinybble << 4) | lonybble;
 195                 num_chars++;
 196
 197                 p1 = NULL;
 198                 p2 = NULL;
 199         }
 200         return num_chars;
 201 }
 202
 203 static const char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 204
 205 /**
 206  * Encode a base64 string into a malloc()ed string caller to free.
 207  *
 208  *From SQUID: adopted from http://ftp.sunet.se/pub2/gnu/vm/base64-encode.c with adjustments
 209  **/
 210 char * base64_encode(const char *data)
 211 {
 212         size_t out_cnt = 0;
 213         size_t len = strlen(data);
 214         size_t output_len = 4 * ((len + 2) / 3) + 2;
 215         const unsigned char *ptr = (const unsigned char *) data;
 216         char *result = malloc(output_len); /* get us plenty of space */
 217         unsigned int bits;
 218
 219         for (; len >= 3; len -= 3) {
 220                 bits = (ptr[0] << 16) + (ptr[1] << 8) + ptr[2];
 221                 ptr += 3;
 222                 result[out_cnt++] = b64[bits >> 18];
 223                 result[out_cnt++] = b64[(bits >> 12) & 0x3f];
 224                 result[out_cnt++] = b64[(bits >> 6) & 0x3f];
 225                 result[out_cnt++] = b64[bits & 0x3f];
 226         }
 227         if (len != 0) {
 228                 bits = ptr[0] << 16;
 229                 if (len > 1)
 230                         bits |= ptr[1] << 8;
 231                 result[out_cnt++] = b64[bits >> 18];
 232                 result[out_cnt++] = b64[(bits >> 12) & 0x3f];
 233                 result[out_cnt++] = (len > 1)? b64[(bits >> 6) & 0x3f]: '=';
 234                 result[out_cnt++] = '=';
 235         }
 236
 237         result[out_cnt] = '\0'; /* terminate */
 238         return result;
 239 }
 240
 241 unsigned int run_ntlm_auth(const char *username,
 242                            const char *domain,
 243                            const char *full_username,
 244                            const char *plaintext_password,
 245                            const u_char *challenge,
 246                            size_t challenge_length,
 247                            const u_char *lm_response,
 248                            size_t lm_response_length,
 249                            const u_char *nt_response,
 250                            size_t nt_response_length,
 251                            u_char nt_key[16],
 252                            char **error_string)
 253 {
 254
 255         pid_t forkret;
 256         int child_in[2];
 257         int child_out[2];
 258         int status;
 259
 260         int authenticated = NOT_AUTHENTICATED; /* not auth */
 261         int got_user_session_key = 0; /* not got key */
 262
 263         char buffer[1024];
 264
 265         FILE *pipe_in;
 266         FILE *pipe_out;
 267
 268         int i;
 269         char *challenge_hex;
 270         char *lm_hex_hash;
 271         char *nt_hex_hash;
 272
 273         /* First see if we have a program to run... */
 274         if (ntlm_auth == NULL)
 275                 return NOT_AUTHENTICATED;
 276
 277         /* Make first child */
 278         if (pipe(child_out) == -1) {
 279                 error("pipe creation failed for child OUT!");
 280                 return NOT_AUTHENTICATED;
 281         }
 282
 283         if (pipe(child_in) == -1) {
 284                 error("pipe creation failed for child IN!");
 285                 return NOT_AUTHENTICATED;
 286         }
 287
 288         forkret = safe_fork(child_in[0], child_out[1], 2);
 289         if (forkret == -1) {
 290                 if (error_string) {
 291                         *error_string = strdup("fork failed!");
 292                 }
 293
 294                 return NOT_AUTHENTICATED;
 295         }
 296
 297         if (forkret == 0) {
 298                 /* child process */
 299                 uid_t uid;
 300
 301                 close(child_out[0]);
 302                 close(child_in[1]);
 303
 304                 /* run winbind as the user that invoked pppd */
 305                 setgid(getgid());
 306                 uid = getuid();
 307                 if (setuid(uid) == -1 || getuid() != uid)
 308                         fatal("pppd/winbind: could not setuid to %d: %m", uid);
 309                 execl("/bin/sh", "sh", "-c", ntlm_auth, NULL);
 310                 fatal("pppd/winbind: could not exec /bin/sh: %m");
 311         }
 312
 313         /* parent */
 314         close(child_out[1]);
 315         close(child_in[0]);
 316
 317         /* Need to write the User's info onto the pipe */
 318
 319         pipe_in = fdopen(child_in[1], "w");
 320
 321         pipe_out = fdopen(child_out[0], "r");
 322
 323         /* look for session key coming back */
 324
 325         if (username) {
 326                 char *b64_username = base64_encode(username);
 327                 fprintf(pipe_in, "Username:: %s\n", b64_username);
 328                 free(b64_username);
 329         }
 330
 331         if (domain) {
 332                 char *b64_domain = base64_encode(domain);
 333                 fprintf(pipe_in, "NT-Domain:: %s\n", b64_domain);
 334                 free(b64_domain);
 335         }
 336
 337         if (full_username) {
 338                 char *b64_full_username = base64_encode(full_username);
 339                 fprintf(pipe_in, "Full-Username:: %s\n", b64_full_username);
 340                 free(b64_full_username);
 341         }
 342
 343         if (plaintext_password) {
 344                 char *b64_plaintext_password = base64_encode(plaintext_password);
 345                 fprintf(pipe_in, "Password:: %s\n", b64_plaintext_password);
 346                 free(b64_plaintext_password);
 347         }
 348
 349         if (challenge_length) {
 350                 fprintf(pipe_in, "Request-User-Session-Key: yes\n");
 351
 352                 challenge_hex = malloc(challenge_length*2+1);
 353
 354                 for (i = 0; i < challenge_length; i++)
 355                         sprintf(challenge_hex + i * 2, "%02X", challenge[i]);
 356
 357                 fprintf(pipe_in, "LANMAN-Challenge: %s\n", challenge_hex);
 358                 free(challenge_hex);
 359         }
 360
 361         if (lm_response_length) {
 362                 lm_hex_hash = malloc(lm_response_length*2+1);
 363
 364                 for (i = 0; i < lm_response_length; i++)
 365                         sprintf(lm_hex_hash + i * 2, "%02X", lm_response[i]);
 366
 367                 fprintf(pipe_in, "LANMAN-response: %s\n", lm_hex_hash);
 368                 free(lm_hex_hash);
 369         }
 370
 371         if (nt_response_length) {
 372                 nt_hex_hash = malloc(nt_response_length*2+1);
 373
 374                 for (i = 0; i < nt_response_length; i++)
 375                         sprintf(nt_hex_hash + i * 2, "%02X", nt_response[i]);
 376
 377                 fprintf(pipe_in, "NT-response: %s\n", nt_hex_hash);
 378                 free(nt_hex_hash);
 379         }
 380
 381         fprintf(pipe_in, ".\n");
 382         fflush(pipe_in);
 383
 384         while (fgets(buffer, sizeof(buffer)-1, pipe_out) != NULL) {
 385                 char *message, *parameter;
 386                 if (buffer[strlen(buffer)-1] != '\n') {
 387                         break;
 388                 }
 389                 buffer[strlen(buffer)-1] = '\0';
 390                 message = buffer;
 391
 392                 if (!(parameter = strstr(buffer, ": "))) {
 393                         break;
 394                 }
 395
 396                 parameter[0] = '\0';
 397                 parameter++;
 398                 parameter[0] = '\0';
 399                 parameter++;
 400
 401                 if (strcmp(message, ".") == 0) {
 402                         /* end of sequence */
 403                         break;
 404                 } else if (strcasecmp(message, "Authenticated") == 0) {
 405                         if (strcasecmp(parameter, "Yes") == 0) {
 406                                 authenticated = AUTHENTICATED;
 407                         } else {
 408                                 notice("Winbind has declined authentication for user!");
 409                                 authenticated = NOT_AUTHENTICATED;
 410                         }
 411                 } else if (strcasecmp(message, "User-session-key") == 0) {
 412                         /* length is the number of characters to parse */
 413                         if (nt_key) {
 414                                 if (strhex_to_str(nt_key, 32, parameter) == 16) {
 415                                         got_user_session_key = 1;
 416                                 } else {
 417                                         notice("NT session key for user was not 16 bytes!");
 418                                 }
 419                         }
 420                 } else if (strcasecmp(message, "Error") == 0) {
 421                         authenticated = NOT_AUTHENTICATED;
 422                         if (error_string)
 423                                 *error_string = strdup(parameter);
 424                 } else if (strcasecmp(message, "Authentication-Error") == 0) {
 425                         authenticated = NOT_AUTHENTICATED;
 426                         if (error_string)
 427                                 *error_string = strdup(parameter);
 428                 } else {
 429                         notice("unrecognised input from ntlm_auth helper - %s: %s", message, parameter);
 430                 }
 431         }
 432
 433         /* parent */
 434         if (close(child_out[0]) == -1) {
 435                 notice("error closing pipe?!? for child OUT[0]");
 436                 return NOT_AUTHENTICATED;
 437         }
 438
 439        /* parent */
 440         if (close(child_in[1]) == -1) {
 441                 notice("error closing pipe?!? for child IN[1]");
 442                 return NOT_AUTHENTICATED;
 443         }
 444
 445         while ((wait(&status) == -1) && errno == EINTR)
 446                 ;
 447
 448         if ((authenticated == AUTHENTICATED) && nt_key && !got_user_session_key) {
 449                 notice("Did not get user session key, despite being authenticated!");
 450                 return NOT_AUTHENTICATED;
 451         }
 452         return authenticated;
 453 }
 454
 455 /**********************************************************************
 456 * %FUNCTION: winbind_secret_check
 457 * %ARGUMENTS:
 458 *  None
 459 * %RETURNS:
 460 *  0 if we don't have an ntlm_auth program to run, otherwise 1.
 461 * %DESCRIPTION:
 462 * Tells pppd that we will try to authenticate the peer, and not to
 463 * worry about looking in /etc/ppp/ *-secrets
 464 ***********************************************************************/
 465 static int
 466 winbind_secret_check(void)
 467 {
 468         return ntlm_auth != NULL;
 469 }
 470
 471 /**********************************************************************
 472 * %FUNCTION: winbind_pap_auth
 473 * %ARGUMENTS:
 474 *  user -- user-name of peer
 475 *  passwd -- password supplied by peer
 476 *  msgp -- Message which will be sent in PAP response
 477 *  paddrs -- set to a list of possible peer IP addresses
 478 *  popts -- set to a list of additional pppd options
 479 * %RETURNS:
 480 *  1 if we can authenticate, -1 if we cannot.
 481 * %DESCRIPTION:
 482 * Performs PAP authentication using WINBIND
 483 ***********************************************************************/
 484 static int
 485 winbind_pap_auth(char *user,
 486                 char *password,
 487                 char **msgp,
 488                 struct wordlist **paddrs,
 489                 struct wordlist **popts)
 490 {
 491         if (run_ntlm_auth(NULL, NULL, user, password, NULL, 0, NULL, 0, NULL, 0, NULL, msgp) == AUTHENTICATED) {
 492                 return 1;
 493         }
 494         return -1;
 495 }
 496
 497 /**********************************************************************
 498 * %FUNCTION: winbind_chap_auth
 499 * %ARGUMENTS:
 500 *  user -- user-name of peer
 501 *  remmd -- hash received from peer
 502 *  remmd_len -- length of remmd
 503 *  cstate -- pppd's chap_state structure
 504 * %RETURNS:
 505 *  AUTHENTICATED (1) if we can authenticate, NOT_AUTHENTICATED (0) if we cannot.
 506 * %DESCRIPTION:
 507 * Performs MS-CHAP and MS-CHAPv2 authentication using WINBIND.
 508 ***********************************************************************/
 509
 510 static int
 511 winbind_chap_verify(char *user, char *ourname, int id,
 512                     struct chap_digest_type *digest,
 513                     unsigned char *challenge,
 514                     unsigned char *response,
 515                     char *message, int message_space)
 516 {
 517         int challenge_len, response_len;
 518         char domainname[256];
 519         char *domain;
 520         char *username;
 521         char *p;
 522         char saresponse[MS_AUTH_RESPONSE_LENGTH+1];
 523
 524         /* The first byte of each of these strings contains their length */
 525         challenge_len = *challenge++;
 526         response_len = *response++;
 527
 528         /* remove domain from "domain\username" */
 529         if ((username = strrchr(user, '\\')) != NULL)
 530                 ++username;
 531         else
 532                 username = user;
 533
 534         strlcpy(domainname, user, sizeof(domainname));
 535
 536         /* remove domain from "domain\username" */
 537         if ((p = strrchr(domainname, '\\')) != NULL) {
 538                 *p = '\0';
 539                 domain = domainname;
 540         } else {
 541                 domain = NULL;
 542         }
 543
 544         /*  generate MD based on negotiated type */
 545         switch (digest->code) {
 546
 547         case CHAP_MICROSOFT:
 548         {
 549                 char *error_string = NULL;
 550                 u_char *nt_response = NULL;
 551                 u_char *lm_response = NULL;
 552                 int nt_response_size = 0;
 553                 int lm_response_size = 0;
 554                 u_char session_key[16];
 555
 556                 if (response_len != MS_CHAP_RESPONSE_LEN)
 557                         break;                  /* not even the right length */
 558
 559                 /* Determine which part of response to verify against */
 560                 if (response[MS_CHAP_USENT]) {
 561                         nt_response = &response[MS_CHAP_NTRESP];
 562                         nt_response_size = MS_CHAP_NTRESP_LEN;
 563                 } else {
 564 #ifdef MSLANMAN
 565                         lm_response = &response[MS_CHAP_LANMANRESP];
 566                         lm_response_size = MS_CHAP_LANMANRESP_LEN;
 567 #else
 568                         /* Should really propagate this into the error packet. */
 569                         notice("Peer request for LANMAN auth not supported");
 570                         return NOT_AUTHENTICATED;
 571 #endif /* MSLANMAN */
 572                 }
 573
 574                 /* ship off to winbind, and check */
 575
 576                 if (run_ntlm_auth(username,
 577                                   domain,
 578                                   NULL,
 579                                   NULL,
 580                                   challenge, challenge_len,
 581                                   lm_response, lm_response_size,
 582                                   nt_response, nt_response_size,
 583                                   session_key,
 584                                   &error_string) == AUTHENTICATED) {
 585                         mppe_set_keys(challenge, session_key);
 586                         slprintf(message, message_space, "Access granted");
 587                         return AUTHENTICATED;
 588
 589                 } else {
 590                         if (error_string) {
 591                                 notice(error_string);
 592                                 free(error_string);
 593                         }
 594                         slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0",
 595                                  challenge_len, challenge);
 596                         return NOT_AUTHENTICATED;
 597                 }
 598                 break;
 599         }
 600
 601         case CHAP_MICROSOFT_V2:
 602         {
 603                 u_char Challenge[8];
 604                 u_char session_key[MD4_SIGNATURE_SIZE];
 605                 char *error_string = NULL;
 606
 607                 if (response_len != MS_CHAP2_RESPONSE_LEN)
 608                         break;                  /* not even the right length */
 609
 610                 ChallengeHash(&response[MS_CHAP2_PEER_CHALLENGE], challenge,
 611                               user, Challenge);
 612
 613                 /* ship off to winbind, and check */
 614
 615                 if (run_ntlm_auth(username,
 616                                   domain,
 617                                   NULL,
 618                                   NULL,
 619                                   Challenge, 8,
 620                                   NULL, 0,
 621                                   &response[MS_CHAP2_NTRESP],
 622                                   MS_CHAP2_NTRESP_LEN,
 623                                   session_key,
 624                                   &error_string) == AUTHENTICATED) {
 625
 626                         GenerateAuthenticatorResponse(session_key,
 627                                 &response[MS_CHAP2_NTRESP],
 628                                 &response[MS_CHAP2_PEER_CHALLENGE],
 629                                 challenge, user, saresponse);
 630                         mppe_set_keys2(session_key, &response[MS_CHAP2_NTRESP],
 631                                        MS_CHAP2_AUTHENTICATOR);
 632                         if (response[MS_CHAP2_FLAGS]) {
 633                                 slprintf(message, message_space, "S=%s", saresponse);
 634                         } else {
 635                                 slprintf(message, message_space, "S=%s M=%s",
 636                                          saresponse, "Access granted");
 637                         }
 638                         return AUTHENTICATED;
 639
 640                 } else {
 641                         if (error_string) {
 642                                 notice(error_string);
 643                                 slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0 M=%s",
 644                                          challenge_len, challenge, error_string);
 645                                 free(error_string);
 646                         } else {
 647                                 slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0 M=%s",
 648                                          challenge_len, challenge, "Access denied");
 649                         }
 650                         return NOT_AUTHENTICATED;
 651                 }
 652                 break;
 653         }
 654
 655         default:
 656                 error("WINBIND: Challenge type %u unsupported", digest->code);
 657         }
 658         return NOT_AUTHENTICATED;
 659 }
 660
 661 static int
 662 winbind_allowed_address(u_int32_t addr)
 663 {
 664         ipcp_options *wo = &ipcp_wantoptions[0];
 665         if (wo->hisaddr !=0 && wo->hisaddr == addr) {
 666                 return 1;
 667         }
 668         return -1;
 669 }