![Nicholas Bellinger](/assets/img/avatar_default.png)
This patch makes chap_server_compute_md5() use proper unsigned long usage for the CHAP_I (identifier) and check for values beyond 255 as per RFC-1994. Reported-by: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
469 lines
12 KiB
C
469 lines
12 KiB
C
/*******************************************************************************
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* This file houses the main functions for the iSCSI CHAP support
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*
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* \u00a9 Copyright 2007-2011 RisingTide Systems LLC.
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*
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* Licensed to the Linux Foundation under the General Public License (GPL) version 2.
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*
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* Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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******************************************************************************/
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/crypto.h>
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#include <linux/err.h>
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#include <linux/scatterlist.h>
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#include "iscsi_target_core.h"
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#include "iscsi_target_nego.h"
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#include "iscsi_target_auth.h"
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static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len)
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{
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int j = DIV_ROUND_UP(len, 2), rc;
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rc = hex2bin(dst, src, j);
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if (rc < 0)
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pr_debug("CHAP string contains non hex digit symbols\n");
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dst[j] = '\0';
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return j;
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}
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static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len)
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{
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int i;
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for (i = 0; i < src_len; i++) {
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sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff);
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}
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}
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static void chap_set_random(char *data, int length)
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{
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long r;
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unsigned n;
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while (length > 0) {
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get_random_bytes(&r, sizeof(long));
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r = r ^ (r >> 8);
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r = r ^ (r >> 4);
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n = r & 0x7;
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get_random_bytes(&r, sizeof(long));
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r = r ^ (r >> 8);
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r = r ^ (r >> 5);
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n = (n << 3) | (r & 0x7);
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get_random_bytes(&r, sizeof(long));
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r = r ^ (r >> 8);
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r = r ^ (r >> 5);
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n = (n << 2) | (r & 0x3);
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*data++ = n;
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length--;
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}
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}
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static void chap_gen_challenge(
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struct iscsi_conn *conn,
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int caller,
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char *c_str,
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unsigned int *c_len)
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{
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unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
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struct iscsi_chap *chap = conn->auth_protocol;
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memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
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chap_set_random(chap->challenge, CHAP_CHALLENGE_LENGTH);
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chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
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CHAP_CHALLENGE_LENGTH);
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/*
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* Set CHAP_C, and copy the generated challenge into c_str.
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*/
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*c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
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*c_len += 1;
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pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
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challenge_asciihex);
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}
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static struct iscsi_chap *chap_server_open(
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struct iscsi_conn *conn,
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struct iscsi_node_auth *auth,
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const char *a_str,
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char *aic_str,
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unsigned int *aic_len)
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{
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struct iscsi_chap *chap;
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if (!(auth->naf_flags & NAF_USERID_SET) ||
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!(auth->naf_flags & NAF_PASSWORD_SET)) {
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pr_err("CHAP user or password not set for"
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" Initiator ACL\n");
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return NULL;
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}
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conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
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if (!conn->auth_protocol)
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return NULL;
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chap = conn->auth_protocol;
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/*
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* We only support MD5 MDA presently.
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*/
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if (strncmp(a_str, "CHAP_A=5", 8)) {
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pr_err("CHAP_A is not MD5.\n");
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return NULL;
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}
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pr_debug("[server] Got CHAP_A=5\n");
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/*
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* Send back CHAP_A set to MD5.
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*/
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*aic_len = sprintf(aic_str, "CHAP_A=5");
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*aic_len += 1;
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chap->digest_type = CHAP_DIGEST_MD5;
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pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
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/*
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* Set Identifier.
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*/
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chap->id = ISCSI_TPG_C(conn)->tpg_chap_id++;
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*aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
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*aic_len += 1;
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pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
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/*
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* Generate Challenge.
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*/
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chap_gen_challenge(conn, 1, aic_str, aic_len);
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return chap;
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}
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static void chap_close(struct iscsi_conn *conn)
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{
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kfree(conn->auth_protocol);
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conn->auth_protocol = NULL;
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}
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static int chap_server_compute_md5(
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struct iscsi_conn *conn,
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struct iscsi_node_auth *auth,
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char *nr_in_ptr,
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char *nr_out_ptr,
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unsigned int *nr_out_len)
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{
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char *endptr;
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unsigned long id;
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unsigned char digest[MD5_SIGNATURE_SIZE];
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unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
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unsigned char identifier[10], *challenge = NULL;
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unsigned char *challenge_binhex = NULL;
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unsigned char client_digest[MD5_SIGNATURE_SIZE];
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unsigned char server_digest[MD5_SIGNATURE_SIZE];
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unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
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struct iscsi_chap *chap = conn->auth_protocol;
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struct crypto_hash *tfm;
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struct hash_desc desc;
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struct scatterlist sg;
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int auth_ret = -1, ret, challenge_len;
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memset(identifier, 0, 10);
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memset(chap_n, 0, MAX_CHAP_N_SIZE);
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memset(chap_r, 0, MAX_RESPONSE_LENGTH);
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memset(digest, 0, MD5_SIGNATURE_SIZE);
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memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
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memset(client_digest, 0, MD5_SIGNATURE_SIZE);
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memset(server_digest, 0, MD5_SIGNATURE_SIZE);
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challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
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if (!challenge) {
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pr_err("Unable to allocate challenge buffer\n");
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goto out;
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}
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challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
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if (!challenge_binhex) {
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pr_err("Unable to allocate challenge_binhex buffer\n");
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goto out;
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}
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/*
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* Extract CHAP_N.
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*/
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if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
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&type) < 0) {
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pr_err("Could not find CHAP_N.\n");
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goto out;
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}
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if (type == HEX) {
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pr_err("Could not find CHAP_N.\n");
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goto out;
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}
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if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) {
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pr_err("CHAP_N values do not match!\n");
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goto out;
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}
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pr_debug("[server] Got CHAP_N=%s\n", chap_n);
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/*
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* Extract CHAP_R.
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*/
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if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
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&type) < 0) {
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pr_err("Could not find CHAP_R.\n");
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goto out;
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}
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if (type != HEX) {
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pr_err("Could not find CHAP_R.\n");
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goto out;
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}
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pr_debug("[server] Got CHAP_R=%s\n", chap_r);
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chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
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tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(tfm)) {
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pr_err("Unable to allocate struct crypto_hash\n");
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goto out;
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}
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desc.tfm = tfm;
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desc.flags = 0;
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ret = crypto_hash_init(&desc);
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if (ret < 0) {
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pr_err("crypto_hash_init() failed\n");
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crypto_free_hash(tfm);
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goto out;
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}
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sg_init_one(&sg, &chap->id, 1);
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ret = crypto_hash_update(&desc, &sg, 1);
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if (ret < 0) {
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pr_err("crypto_hash_update() failed for id\n");
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crypto_free_hash(tfm);
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goto out;
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}
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sg_init_one(&sg, &auth->password, strlen(auth->password));
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ret = crypto_hash_update(&desc, &sg, strlen(auth->password));
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if (ret < 0) {
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pr_err("crypto_hash_update() failed for password\n");
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crypto_free_hash(tfm);
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goto out;
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}
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sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH);
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ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH);
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if (ret < 0) {
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pr_err("crypto_hash_update() failed for challenge\n");
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crypto_free_hash(tfm);
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goto out;
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}
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ret = crypto_hash_final(&desc, server_digest);
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if (ret < 0) {
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pr_err("crypto_hash_final() failed for server digest\n");
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crypto_free_hash(tfm);
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goto out;
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}
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crypto_free_hash(tfm);
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chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
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pr_debug("[server] MD5 Server Digest: %s\n", response);
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if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
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pr_debug("[server] MD5 Digests do not match!\n\n");
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goto out;
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} else
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pr_debug("[server] MD5 Digests match, CHAP connetication"
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" successful.\n\n");
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/*
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* One way authentication has succeeded, return now if mutual
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* authentication is not enabled.
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*/
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if (!auth->authenticate_target) {
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kfree(challenge);
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kfree(challenge_binhex);
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return 0;
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}
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/*
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* Get CHAP_I.
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*/
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if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
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pr_err("Could not find CHAP_I.\n");
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goto out;
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}
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if (type == HEX)
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id = simple_strtoul(&identifier[2], &endptr, 0);
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else
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id = simple_strtoul(identifier, &endptr, 0);
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if (id > 255) {
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pr_err("chap identifier: %lu greater than 255\n", id);
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goto out;
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}
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/*
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* RFC 1994 says Identifier is no more than octet (8 bits).
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*/
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pr_debug("[server] Got CHAP_I=%lu\n", id);
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/*
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* Get CHAP_C.
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*/
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if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
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challenge, &type) < 0) {
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pr_err("Could not find CHAP_C.\n");
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goto out;
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}
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if (type != HEX) {
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pr_err("Could not find CHAP_C.\n");
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goto out;
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}
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pr_debug("[server] Got CHAP_C=%s\n", challenge);
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challenge_len = chap_string_to_hex(challenge_binhex, challenge,
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strlen(challenge));
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if (!challenge_len) {
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pr_err("Unable to convert incoming challenge\n");
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goto out;
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}
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/*
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* Generate CHAP_N and CHAP_R for mutual authentication.
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*/
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tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(tfm)) {
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pr_err("Unable to allocate struct crypto_hash\n");
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goto out;
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}
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desc.tfm = tfm;
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desc.flags = 0;
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ret = crypto_hash_init(&desc);
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if (ret < 0) {
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pr_err("crypto_hash_init() failed\n");
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crypto_free_hash(tfm);
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goto out;
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}
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sg_init_one(&sg, &id, 1);
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ret = crypto_hash_update(&desc, &sg, 1);
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if (ret < 0) {
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pr_err("crypto_hash_update() failed for id\n");
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crypto_free_hash(tfm);
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goto out;
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}
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sg_init_one(&sg, auth->password_mutual,
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strlen(auth->password_mutual));
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ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual));
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if (ret < 0) {
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pr_err("crypto_hash_update() failed for"
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" password_mutual\n");
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crypto_free_hash(tfm);
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goto out;
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}
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/*
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* Convert received challenge to binary hex.
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*/
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sg_init_one(&sg, challenge_binhex, challenge_len);
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ret = crypto_hash_update(&desc, &sg, challenge_len);
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if (ret < 0) {
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pr_err("crypto_hash_update() failed for ma challenge\n");
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crypto_free_hash(tfm);
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goto out;
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}
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ret = crypto_hash_final(&desc, digest);
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if (ret < 0) {
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pr_err("crypto_hash_final() failed for ma digest\n");
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crypto_free_hash(tfm);
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goto out;
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}
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crypto_free_hash(tfm);
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/*
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* Generate CHAP_N and CHAP_R.
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*/
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*nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
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*nr_out_len += 1;
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pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
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/*
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* Convert response from binary hex to ascii hext.
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*/
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chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
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*nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
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response);
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*nr_out_len += 1;
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pr_debug("[server] Sending CHAP_R=0x%s\n", response);
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auth_ret = 0;
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out:
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kfree(challenge);
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kfree(challenge_binhex);
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return auth_ret;
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}
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static int chap_got_response(
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struct iscsi_conn *conn,
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struct iscsi_node_auth *auth,
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char *nr_in_ptr,
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char *nr_out_ptr,
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unsigned int *nr_out_len)
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{
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struct iscsi_chap *chap = conn->auth_protocol;
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switch (chap->digest_type) {
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case CHAP_DIGEST_MD5:
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if (chap_server_compute_md5(conn, auth, nr_in_ptr,
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nr_out_ptr, nr_out_len) < 0)
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return -1;
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return 0;
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default:
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pr_err("Unknown CHAP digest type %d!\n",
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chap->digest_type);
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return -1;
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}
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}
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u32 chap_main_loop(
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struct iscsi_conn *conn,
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struct iscsi_node_auth *auth,
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char *in_text,
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char *out_text,
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int *in_len,
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int *out_len)
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{
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struct iscsi_chap *chap = conn->auth_protocol;
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if (!chap) {
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chap = chap_server_open(conn, auth, in_text, out_text, out_len);
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if (!chap)
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return 2;
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chap->chap_state = CHAP_STAGE_SERVER_AIC;
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return 0;
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} else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
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convert_null_to_semi(in_text, *in_len);
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if (chap_got_response(conn, auth, in_text, out_text,
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out_len) < 0) {
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chap_close(conn);
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return 2;
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}
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if (auth->authenticate_target)
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chap->chap_state = CHAP_STAGE_SERVER_NR;
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else
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*out_len = 0;
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chap_close(conn);
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return 1;
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}
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return 2;
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}
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