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