drivers/target/iscsi/iscsi_target_auth.c - arm/linux-arm-legacy - Git at Google

 /*******************************************************************************
  * This file houses the main functions for the iSCSI CHAP support
  *
  * (c) Copyright 2007-2013 Datera, Inc.
  *
  * 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 = conn->tpg->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];
 	size_t compare_len;
 	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;
 	}

 	/* Include the terminating NULL in the compare */
 	compare_len = strlen(auth->userid) + 1;
 	if (strncmp(chap_n, auth->userid, compare_len) != 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;
 }
	/*******************************************************************************
	* This file houses the main functions for the iSCSI CHAP support
	*
	* (c) Copyright 2007-2013 Datera, Inc.
	*
	* 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 = conn->tpg->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];
	size_t compare_len;
	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;
	}

	/* Include the terminating NULL in the compare */
	compare_len = strlen(auth->userid) + 1;
	if (strncmp(chap_n, auth->userid, compare_len) != 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;
	}