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