532 lines
12 KiB
C
532 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*******************************************************************************
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* This file houses the main functions for the iSCSI CHAP support
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*
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* (c) Copyright 2007-2013 Datera, Inc.
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*
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* Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
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*
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******************************************************************************/
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#include <crypto/hash.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/err.h>
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#include <linux/random.h>
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#include <linux/scatterlist.h>
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#include <target/iscsi/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 char *chap_get_digest_name(const int digest_type)
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{
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switch (digest_type) {
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case CHAP_DIGEST_MD5:
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return "md5";
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case CHAP_DIGEST_SHA1:
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return "sha1";
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case CHAP_DIGEST_SHA256:
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return "sha256";
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case CHAP_DIGEST_SHA3_256:
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return "sha3-256";
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default:
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return NULL;
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}
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}
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static int 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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int ret;
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unsigned char *challenge_asciihex;
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struct iscsi_chap *chap = conn->auth_protocol;
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challenge_asciihex = kzalloc(chap->challenge_len * 2 + 1, GFP_KERNEL);
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if (!challenge_asciihex)
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return -ENOMEM;
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memset(chap->challenge, 0, MAX_CHAP_CHALLENGE_LEN);
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ret = get_random_bytes_wait(chap->challenge, chap->challenge_len);
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if (unlikely(ret))
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goto out;
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bin2hex(challenge_asciihex, chap->challenge,
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chap->challenge_len);
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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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out:
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kfree(challenge_asciihex);
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return ret;
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}
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static int chap_test_algorithm(const char *name)
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{
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struct crypto_shash *tfm;
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tfm = crypto_alloc_shash(name, 0, 0);
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if (IS_ERR(tfm))
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return -1;
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crypto_free_shash(tfm);
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return 0;
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}
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static int chap_check_algorithm(const char *a_str)
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{
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char *tmp, *orig, *token, *digest_name;
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long digest_type;
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int r = CHAP_DIGEST_UNKNOWN;
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tmp = kstrdup(a_str, GFP_KERNEL);
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if (!tmp) {
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pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
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return CHAP_DIGEST_UNKNOWN;
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}
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orig = tmp;
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token = strsep(&tmp, "=");
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if (!token)
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goto out;
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if (strcmp(token, "CHAP_A")) {
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pr_err("Unable to locate CHAP_A key\n");
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goto out;
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}
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while (token) {
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token = strsep(&tmp, ",");
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if (!token)
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goto out;
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if (kstrtol(token, 10, &digest_type))
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continue;
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digest_name = chap_get_digest_name(digest_type);
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if (!digest_name)
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continue;
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pr_debug("Selected %s Algorithm\n", digest_name);
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if (chap_test_algorithm(digest_name) < 0) {
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pr_err("failed to allocate %s algo\n", digest_name);
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} else {
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r = digest_type;
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goto out;
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}
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}
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out:
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kfree(orig);
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return r;
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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 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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int digest_type;
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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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digest_type = chap_check_algorithm(a_str);
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switch (digest_type) {
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case CHAP_DIGEST_MD5:
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chap->digest_size = MD5_SIGNATURE_SIZE;
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break;
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case CHAP_DIGEST_SHA1:
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chap->digest_size = SHA1_SIGNATURE_SIZE;
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break;
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case CHAP_DIGEST_SHA256:
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chap->digest_size = SHA256_SIGNATURE_SIZE;
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break;
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case CHAP_DIGEST_SHA3_256:
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chap->digest_size = SHA3_256_SIGNATURE_SIZE;
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break;
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case CHAP_DIGEST_UNKNOWN:
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default:
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pr_err("Unsupported CHAP_A value\n");
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chap_close(conn);
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return NULL;
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}
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chap->digest_name = chap_get_digest_name(digest_type);
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/* Tie the challenge length to the digest size */
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chap->challenge_len = chap->digest_size;
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pr_debug("[server] Got CHAP_A=%d\n", digest_type);
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*aic_len = sprintf(aic_str, "CHAP_A=%d", digest_type);
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*aic_len += 1;
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pr_debug("[server] Sending CHAP_A=%d\n", digest_type);
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/*
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* Set Identifier.
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*/
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chap->id = conn->tpg->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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if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) {
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chap_close(conn);
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return NULL;
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}
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return chap;
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}
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static int chap_server_compute_hash(
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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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unsigned long id;
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unsigned char id_as_uchar;
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unsigned char type;
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unsigned char identifier[10], *initiatorchg = NULL;
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unsigned char *initiatorchg_binhex = NULL;
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unsigned char *digest = NULL;
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unsigned char *response = NULL;
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unsigned char *client_digest = NULL;
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unsigned char *server_digest = NULL;
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unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
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size_t compare_len;
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struct iscsi_chap *chap = conn->auth_protocol;
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struct crypto_shash *tfm = NULL;
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struct shash_desc *desc = NULL;
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int auth_ret = -1, ret, initiatorchg_len;
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digest = kzalloc(chap->digest_size, GFP_KERNEL);
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if (!digest) {
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pr_err("Unable to allocate the digest buffer\n");
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goto out;
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}
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response = kzalloc(chap->digest_size * 2 + 2, GFP_KERNEL);
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if (!response) {
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pr_err("Unable to allocate the response buffer\n");
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goto out;
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}
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client_digest = kzalloc(chap->digest_size, GFP_KERNEL);
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if (!client_digest) {
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pr_err("Unable to allocate the client_digest buffer\n");
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goto out;
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}
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server_digest = kzalloc(chap->digest_size, GFP_KERNEL);
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if (!server_digest) {
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pr_err("Unable to allocate the server_digest buffer\n");
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goto out;
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}
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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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initiatorchg = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
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if (!initiatorchg) {
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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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initiatorchg_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
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if (!initiatorchg_binhex) {
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pr_err("Unable to allocate initiatorchg_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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/* Include the terminating NULL in the compare */
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compare_len = strlen(auth->userid) + 1;
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if (strncmp(chap_n, auth->userid, compare_len) != 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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if (strlen(chap_r) != chap->digest_size * 2) {
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pr_err("Malformed CHAP_R\n");
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goto out;
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}
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if (hex2bin(client_digest, chap_r, chap->digest_size) < 0) {
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pr_err("Malformed 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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tfm = crypto_alloc_shash(chap->digest_name, 0, 0);
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if (IS_ERR(tfm)) {
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tfm = NULL;
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pr_err("Unable to allocate struct crypto_shash\n");
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goto out;
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}
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desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
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if (!desc) {
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pr_err("Unable to allocate struct shash_desc\n");
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goto out;
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}
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desc->tfm = tfm;
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ret = crypto_shash_init(desc);
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if (ret < 0) {
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pr_err("crypto_shash_init() failed\n");
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goto out;
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}
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ret = crypto_shash_update(desc, &chap->id, 1);
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if (ret < 0) {
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pr_err("crypto_shash_update() failed for id\n");
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goto out;
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}
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ret = crypto_shash_update(desc, (char *)&auth->password,
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strlen(auth->password));
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if (ret < 0) {
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pr_err("crypto_shash_update() failed for password\n");
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goto out;
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}
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ret = crypto_shash_finup(desc, chap->challenge,
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chap->challenge_len, server_digest);
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if (ret < 0) {
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pr_err("crypto_shash_finup() failed for challenge\n");
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goto out;
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}
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bin2hex(response, server_digest, chap->digest_size);
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pr_debug("[server] %s Server Digest: %s\n",
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chap->digest_name, response);
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if (memcmp(server_digest, client_digest, chap->digest_size) != 0) {
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pr_debug("[server] %s Digests do not match!\n\n",
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chap->digest_name);
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goto out;
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} else
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pr_debug("[server] %s Digests match, CHAP connection"
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" successful.\n\n", chap->digest_name);
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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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auth_ret = 0;
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goto out;
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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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ret = kstrtoul(&identifier[2], 0, &id);
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else
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ret = kstrtoul(identifier, 0, &id);
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if (ret < 0) {
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pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
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goto out;
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}
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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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initiatorchg, &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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initiatorchg_len = DIV_ROUND_UP(strlen(initiatorchg), 2);
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if (!initiatorchg_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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if (initiatorchg_len > 1024) {
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pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
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goto out;
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}
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if (hex2bin(initiatorchg_binhex, initiatorchg, initiatorchg_len) < 0) {
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pr_err("Malformed 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", initiatorchg);
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/*
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* During mutual authentication, the CHAP_C generated by the
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* initiator must not match the original CHAP_C generated by
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* the target.
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*/
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if (initiatorchg_len == chap->challenge_len &&
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!memcmp(initiatorchg_binhex, chap->challenge,
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initiatorchg_len)) {
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pr_err("initiator CHAP_C matches target CHAP_C, failing"
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" login attempt\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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ret = crypto_shash_init(desc);
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if (ret < 0) {
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pr_err("crypto_shash_init() failed\n");
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goto out;
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}
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/* To handle both endiannesses */
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id_as_uchar = id;
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ret = crypto_shash_update(desc, &id_as_uchar, 1);
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if (ret < 0) {
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pr_err("crypto_shash_update() failed for id\n");
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goto out;
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}
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ret = crypto_shash_update(desc, auth->password_mutual,
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strlen(auth->password_mutual));
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if (ret < 0) {
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pr_err("crypto_shash_update() failed for"
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" password_mutual\n");
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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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ret = crypto_shash_finup(desc, initiatorchg_binhex, initiatorchg_len,
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digest);
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if (ret < 0) {
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pr_err("crypto_shash_finup() failed for ma 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.
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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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bin2hex(response, digest, chap->digest_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_sensitive(desc);
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if (tfm)
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crypto_free_shash(tfm);
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kfree(initiatorchg);
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kfree(initiatorchg_binhex);
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kfree(digest);
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kfree(response);
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kfree(server_digest);
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kfree(client_digest);
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return auth_ret;
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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_server_compute_hash(conn, auth, in_text, out_text,
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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;
|
|
}
|