1/*
2 * chap-md5.c - New CHAP/MD5 implementation.
3 *
4 * Copyright (c) 2003 Paul Mackerras. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. The name(s) of the authors of this software must not be used to
14 *    endorse or promote products derived from this software without
15 *    prior written permission.
16 *
17 * 3. Redistributions of any form whatsoever must retain the following
18 *    acknowledgment:
19 *    "This product includes software developed by Paul Mackerras
20 *     <paulus@samba.org>".
21 *
22 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
23 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
24 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
25 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
26 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
27 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
28 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
29 */
30
31#include "netif/ppp/ppp_opts.h"
32#if PPP_SUPPORT && CHAP_SUPPORT  /* don't build if not configured for use in lwipopts.h */
33
34#if 0 /* UNUSED */
35#include <stdlib.h>
36#include <string.h>
37#endif /* UNUSED */
38
39#include "netif/ppp/ppp_impl.h"
40
41#include "netif/ppp/chap-new.h"
42#include "netif/ppp/chap-md5.h"
43#include "netif/ppp/magic.h"
44#include "netif/ppp/pppcrypt.h"
45
46#define MD5_HASH_SIZE		16
47#define MD5_MIN_CHALLENGE	17
48#define MD5_MAX_CHALLENGE	24
49#define MD5_MIN_MAX_POWER_OF_TWO_CHALLENGE     3   /* 2^3-1 = 7, 17+7 = 24 */
50
51#if PPP_SERVER
52static void chap_md5_generate_challenge(ppp_pcb *pcb, unsigned char *cp) {
53	int clen;
54	LWIP_UNUSED_ARG(pcb);
55
56	clen = MD5_MIN_CHALLENGE + magic_pow(MD5_MIN_MAX_POWER_OF_TWO_CHALLENGE);
57	*cp++ = clen;
58	magic_random_bytes(cp, clen);
59}
60
61static int chap_md5_verify_response(ppp_pcb *pcb, int id, const char *name,
62			 const unsigned char *secret, int secret_len,
63			 const unsigned char *challenge, const unsigned char *response,
64			 char *message, int message_space) {
65	lwip_md5_context ctx;
66	unsigned char idbyte = id;
67	unsigned char hash[MD5_HASH_SIZE];
68	int challenge_len, response_len;
69	LWIP_UNUSED_ARG(name);
70	LWIP_UNUSED_ARG(pcb);
71
72	challenge_len = *challenge++;
73	response_len = *response++;
74	if (response_len == MD5_HASH_SIZE) {
75		/* Generate hash of ID, secret, challenge */
76		lwip_md5_init(&ctx);
77		lwip_md5_starts(&ctx);
78		lwip_md5_update(&ctx, &idbyte, 1);
79		lwip_md5_update(&ctx, secret, secret_len);
80		lwip_md5_update(&ctx, challenge, challenge_len);
81		lwip_md5_finish(&ctx, hash);
82		lwip_md5_free(&ctx);
83
84		/* Test if our hash matches the peer's response */
85		if (memcmp(hash, response, MD5_HASH_SIZE) == 0) {
86			ppp_slprintf(message, message_space, "Access granted");
87			return 1;
88		}
89	}
90	ppp_slprintf(message, message_space, "Access denied");
91	return 0;
92}
93#endif /* PPP_SERVER */
94
95static void chap_md5_make_response(ppp_pcb *pcb, unsigned char *response, int id, const char *our_name,
96		       const unsigned char *challenge, const char *secret, int secret_len,
97		       unsigned char *private_) {
98	lwip_md5_context ctx;
99	unsigned char idbyte = id;
100	int challenge_len = *challenge++;
101	LWIP_UNUSED_ARG(our_name);
102	LWIP_UNUSED_ARG(private_);
103	LWIP_UNUSED_ARG(pcb);
104
105	lwip_md5_init(&ctx);
106	lwip_md5_starts(&ctx);
107	lwip_md5_update(&ctx, &idbyte, 1);
108	lwip_md5_update(&ctx, (const u_char *)secret, secret_len);
109	lwip_md5_update(&ctx, challenge, challenge_len);
110	lwip_md5_finish(&ctx, &response[1]);
111	lwip_md5_free(&ctx);
112	response[0] = MD5_HASH_SIZE;
113}
114
115const struct chap_digest_type md5_digest = {
116	CHAP_MD5,		/* code */
117#if PPP_SERVER
118	chap_md5_generate_challenge,
119	chap_md5_verify_response,
120#endif /* PPP_SERVER */
121	chap_md5_make_response,
122	NULL,			/* check_success */
123	NULL,			/* handle_failure */
124};
125
126#endif /* PPP_SUPPORT && CHAP_SUPPORT */
127