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. 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 /*
32  * CHAP packets begin with a standard header with code, id, len (2 bytes).
33  */
34 #define CHAP_HDRLEN	4
35 
36 /*
37  * Values for the code field.
38  */
39 #define CHAP_CHALLENGE	1
40 #define CHAP_RESPONSE	2
41 #define CHAP_SUCCESS	3
42 #define CHAP_FAILURE	4
43 
44 /*
45  * CHAP digest codes.
46  */
47 #define CHAP_MD5		5
48 #define CHAP_MICROSOFT		0x80
49 #define CHAP_MICROSOFT_V2	0x81
50 
51 /*
52  * Semi-arbitrary limits on challenge and response fields.
53  */
54 #define MAX_CHALLENGE_LEN	64
55 #define MAX_RESPONSE_LEN	64
56 
57 /* bitmask of supported algorithms */
58 #define MDTYPE_MICROSOFT_V2	0x1
59 #define MDTYPE_MICROSOFT	0x2
60 #define MDTYPE_MD5		0x4
61 #define MDTYPE_NONE		0
62 
63 /* hashes supported by this instance of pppd */
64 extern int chap_mdtype_all;
65 
66 /* Return the digest alg. ID for the most preferred digest type. */
67 #define CHAP_DIGEST(mdtype) \
68     ((mdtype) & MDTYPE_MD5)? CHAP_MD5: \
69     ((mdtype) & MDTYPE_MICROSOFT_V2)? CHAP_MICROSOFT_V2: \
70     ((mdtype) & MDTYPE_MICROSOFT)? CHAP_MICROSOFT: \
71     0
72 
73 /* Return the bit flag (lsb set) for our most preferred digest type. */
74 #define CHAP_MDTYPE(mdtype) ((mdtype) ^ ((mdtype) - 1)) & (mdtype)
75 
76 /* Return the bit flag for a given digest algorithm ID. */
77 #define CHAP_MDTYPE_D(digest) \
78     ((digest) == CHAP_MICROSOFT_V2)? MDTYPE_MICROSOFT_V2: \
79     ((digest) == CHAP_MICROSOFT)? MDTYPE_MICROSOFT: \
80     ((digest) == CHAP_MD5)? MDTYPE_MD5: \
81     0
82 
83 /* Can we do the requested digest? */
84 #define CHAP_CANDIGEST(mdtype, digest) \
85     ((digest) == CHAP_MICROSOFT_V2)? (mdtype) & MDTYPE_MICROSOFT_V2: \
86     ((digest) == CHAP_MICROSOFT)? (mdtype) & MDTYPE_MICROSOFT: \
87     ((digest) == CHAP_MD5)? (mdtype) & MDTYPE_MD5: \
88     0
89 
90 /*
91  * The code for each digest type has to supply one of these.
92  */
93 struct chap_digest_type {
94 	int code;
95 
96 	/*
97 	 * Note: challenge and response arguments below are formatted as
98 	 * a length byte followed by the actual challenge/response data.
99 	 */
100 	void (*generate_challenge)(unsigned char *challenge);
101 	int (*verify_response)(int id, char *name,
102 		unsigned char *secret, int secret_len,
103 		unsigned char *challenge, unsigned char *response,
104 		char *message, int message_space);
105 	void (*make_response)(unsigned char *response, int id, char *our_name,
106 		unsigned char *challenge, char *secret, int secret_len,
107 		unsigned char *priv);
108 	int (*check_success)(int id, unsigned char *pkt, int len);
109 	void (*handle_failure)(unsigned char *pkt, int len);
110 
111 	struct chap_digest_type *next;
112 };
113 
114 /* Hook for a plugin to validate CHAP challenge */
115 extern int (*chap_verify_hook)(char *name, char *ourname, int id,
116 			struct chap_digest_type *digest,
117 			unsigned char *challenge, unsigned char *response,
118 			char *message, int message_space);
119 
120 /* Called by digest code to register a digest type */
121 extern void chap_register_digest(struct chap_digest_type *);
122 
123 /* Called by authentication code to start authenticating the peer. */
124 extern void chap_auth_peer(int unit, char *our_name, int digest_code);
125 
126 /* Called by auth. code to start authenticating us to the peer. */
127 extern void chap_auth_with_peer(int unit, char *our_name, int digest_code);
128 
129 /* Represents the CHAP protocol to the main pppd code */
130 extern struct protent chap_protent;
131