1/*
2 * chap-new.c - New CHAP 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. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in
15 *    the documentation and/or other materials provided with the
16 *    distribution.
17 *
18 * 3. The name(s) of the authors of this software must not be used to
19 *    endorse or promote products derived from this software without
20 *    prior written permission.
21 *
22 * 4. Redistributions of any form whatsoever must retain the following
23 *    acknowledgment:
24 *    "This product includes software developed by Paul Mackerras
25 *     <paulus@samba.org>".
26 *
27 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
28 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
29 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
30 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
31 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
32 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
33 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
34 */
35
36/*
37 * CHAP packets begin with a standard header with code, id, len (2 bytes).
38 */
39#define CHAP_HDRLEN	4
40
41/*
42 * Values for the code field.
43 */
44#define CHAP_CHALLENGE	1
45#define CHAP_RESPONSE	2
46#define CHAP_SUCCESS	3
47#define CHAP_FAILURE	4
48
49/*
50 * CHAP digest codes.
51 */
52#define CHAP_MD5		5
53#define CHAP_MICROSOFT		0x80
54#define CHAP_MICROSOFT_V2	0x81
55
56/*
57 * Semi-arbitrary limits on challenge and response fields.
58 */
59#define MAX_CHALLENGE_LEN	64
60#define MAX_RESPONSE_LEN	64
61
62/* bitmask of supported algorithms */
63#define MDTYPE_MICROSOFT_V2	0x1
64#define MDTYPE_MICROSOFT	0x2
65#define MDTYPE_MD5		0x4
66
67#ifdef CHAPMS
68#define MDTYPE_ALL (MDTYPE_MICROSOFT_V2 | MDTYPE_MICROSOFT | MDTYPE_MD5)
69#else
70#define MDTYPE_ALL (MDTYPE_MD5)
71#endif
72#define MDTYPE_NONE 0
73
74/* Return the digest alg. ID for the most preferred digest type. */
75#define CHAP_DIGEST(mdtype) \
76    ((mdtype) & MDTYPE_MICROSOFT_V2)? CHAP_MICROSOFT_V2: \
77    ((mdtype) & MDTYPE_MICROSOFT)? CHAP_MICROSOFT: \
78    ((mdtype) & MDTYPE_MD5)? CHAP_MD5: \
79    0
80
81/* Return the bit flag (lsb set) for our most preferred digest type. */
82#define CHAP_MDTYPE(mdtype) ((mdtype) ^ ((mdtype) - 1)) & (mdtype)
83
84/* Return the bit flag for a given digest algorithm ID. */
85#define CHAP_MDTYPE_D(digest) \
86    ((digest) == CHAP_MICROSOFT_V2)? MDTYPE_MICROSOFT_V2: \
87    ((digest) == CHAP_MICROSOFT)? MDTYPE_MICROSOFT: \
88    ((digest) == CHAP_MD5)? MDTYPE_MD5: \
89    0
90
91/* Can we do the requested digest? */
92#define CHAP_CANDIGEST(mdtype, digest) \
93    ((digest) == CHAP_MICROSOFT_V2)? (mdtype) & MDTYPE_MICROSOFT_V2: \
94    ((digest) == CHAP_MICROSOFT)? (mdtype) & MDTYPE_MICROSOFT: \
95    ((digest) == CHAP_MD5)? (mdtype) & MDTYPE_MD5: \
96    0
97
98/*
99 * The code for each digest type has to supply one of these.
100 */
101struct chap_digest_type {
102	int code;
103
104	/*
105	 * Note: challenge and response arguments below are formatted as
106	 * a length byte followed by the actual challenge/response data.
107	 */
108	void (*generate_challenge)(unsigned char *challenge);
109	int (*verify_response)(int id, char *name,
110		unsigned char *secret, int secret_len,
111		unsigned char *challenge, unsigned char *response,
112		char *message, int message_space);
113	void (*make_response)(unsigned char *response, int id, char *our_name,
114		unsigned char *challenge, char *secret, int secret_len,
115		unsigned char *priv);
116	int (*check_success)(unsigned char *pkt, int len, unsigned char *priv);
117	void (*handle_failure)(unsigned char *pkt, int len);
118
119	struct chap_digest_type *next;
120};
121
122/* Hook for a plugin to validate CHAP challenge */
123extern int (*chap_verify_hook)(char *name, char *ourname, int id,
124			struct chap_digest_type *digest,
125			unsigned char *challenge, unsigned char *response,
126			unsigned char *message, int message_space);
127
128/* Called by digest code to register a digest type */
129extern void chap_register_digest(struct chap_digest_type *);
130
131/* Called by authentication code to start authenticating the peer. */
132extern void chap_auth_peer(int unit, char *our_name, int digest_code);
133
134/* Called by auth. code to start authenticating us to the peer. */
135extern void chap_auth_with_peer(int unit, char *our_name, int digest_code);
136
137/* Represents the CHAP protocol to the main pppd code */
138extern struct protent chap_protent;
139