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If anything goes wrong in preparing a CHAP Response, return a 0-length response instead of leaving the length field uninitialized. Also print a warning message to say that something went wrong. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
155 lines
3.9 KiB
C
155 lines
3.9 KiB
C
/*
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* chap-md5.c - New CHAP/MD5 implementation.
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*
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* Copyright (c) 2003 Paul Mackerras. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. The name(s) of the authors of this software must not be used to
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* endorse or promote products derived from this software without
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* prior written permission.
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*
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* 3. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by Paul Mackerras
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* <paulus@ozlabs.org>".
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*
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* THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
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* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
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* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
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* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
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* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#define RCSID "$Id: chap-md5.c,v 1.4 2004/11/09 22:39:25 paulus Exp $"
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include "pppd-private.h"
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#include "chap.h"
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#include "chap-md5.h"
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#include "magic.h"
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#include "crypto.h"
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#define MD5_MIN_CHALLENGE 16
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#define MD5_MAX_CHALLENGE 24
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static void
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chap_md5_generate_challenge(unsigned char *cp)
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{
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int clen;
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clen = (int)(drand48() * (MD5_MAX_CHALLENGE - MD5_MIN_CHALLENGE))
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+ MD5_MIN_CHALLENGE;
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*cp++ = clen;
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random_bytes(cp, clen);
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}
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static int
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chap_md5_verify_response(int id, char *name,
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unsigned char *secret, int secret_len,
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unsigned char *challenge, unsigned char *response,
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char *message, int message_space)
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{
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unsigned char idbyte = id;
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unsigned char hash[MD5_DIGEST_LENGTH];
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unsigned int hash_len = MD5_DIGEST_LENGTH;
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int challenge_len, response_len;
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bool success = 0;
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challenge_len = *challenge++;
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response_len = *response++;
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if (response_len == MD5_DIGEST_LENGTH) {
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/* Generate hash of ID, secret, challenge */
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PPP_MD_CTX* ctx = PPP_MD_CTX_new();
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if (ctx) {
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if (PPP_DigestInit(ctx, PPP_md5())) {
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if (PPP_DigestUpdate(ctx, &idbyte, 1)) {
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if (PPP_DigestUpdate(ctx, secret, secret_len)) {
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if (PPP_DigestUpdate(ctx, challenge, challenge_len)) {
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if (PPP_DigestFinal(ctx, hash, &hash_len)) {
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success = 1;
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}
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}
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}
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}
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}
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PPP_MD_CTX_free(ctx);
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}
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}
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if (success && memcmp(hash, response, hash_len) == 0) {
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slprintf(message, message_space, "Access granted");
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return 1;
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}
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slprintf(message, message_space, "Access denied");
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return 0;
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}
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static void
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chap_md5_make_response(unsigned char *response, int id, char *our_name,
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unsigned char *challenge, char *secret, int secret_len,
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unsigned char *private)
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{
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unsigned char idbyte = id;
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int challenge_len = *challenge++;
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int hash_len = MD5_DIGEST_LENGTH;
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response[0] = 0;
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PPP_MD_CTX* ctx = PPP_MD_CTX_new();
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if (ctx) {
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if (PPP_DigestInit(ctx, PPP_md5())) {
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if (PPP_DigestUpdate(ctx, &idbyte, 1)) {
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if (PPP_DigestUpdate(ctx, secret, secret_len)) {
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if (PPP_DigestUpdate(ctx, challenge, challenge_len)) {
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if (PPP_DigestFinal(ctx, &response[1], &hash_len)) {
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response[0] = hash_len;
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}
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}
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}
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}
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}
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PPP_MD_CTX_free(ctx);
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}
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if (response[0] == 0)
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warn("Error occurred in preparing CHAP-Response");
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}
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static struct chap_digest_type md5_digest = {
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CHAP_MD5, /* code */
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chap_md5_generate_challenge,
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chap_md5_verify_response,
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chap_md5_make_response,
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NULL, /* check_success */
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NULL, /* handle_failure */
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};
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void
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chap_md5_init(void)
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{
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chap_register_digest(&md5_digest);
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}
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