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
62static char *ntlm_auth = NULL;
63
64static 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
84static 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
90static int
91winbind_secret_check(void);
92
93static int winbind_pap_auth(char *user,
94			   char *passwd,
95			   char **msgp,
96			   struct wordlist **paddrs,
97			   struct wordlist **popts);
98static 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);
103static int winbind_allowed_address(u_int32_t addr);
104
105char pppd_version[] = VERSION;
106
107/**********************************************************************
108* %FUNCTION: plugin_init
109* %ARGUMENTS:
110*  None
111* %RETURNS:
112*  Nothing
113* %DESCRIPTION:
114*  Initializes WINBIND plugin.
115***********************************************************************/
116void
117plugin_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
168size_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
203static 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 **/
210char * 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
241unsigned 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***********************************************************************/
465static int
466winbind_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***********************************************************************/
484static int
485winbind_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
510static int
511winbind_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
661static int
662winbind_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}
670