/******************************************************************************* * 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_set_random(char *data, int length) { long r; unsigned n; while (length > 0) { get_random_bytes(&r, sizeof(long)); r = r ^ (r >> 8); r = r ^ (r >> 4); n = r & 0x7; get_random_bytes(&r, sizeof(long)); r = r ^ (r >> 8); r = r ^ (r >> 5); n = (n << 3) | (r & 0x7); get_random_bytes(&r, sizeof(long)); r = r ^ (r >> 8); r = r ^ (r >> 5); n = (n << 2) | (r & 0x3); *data++ = n; length--; } } 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 = (struct iscsi_chap *) conn->auth_protocol; memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1); chap_set_random(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 = (struct iscsi_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 char id, 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 = (struct iscsi_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, (void *)&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, (void *)&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, (void *)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 = (unsigned char)simple_strtoul((char *)&identifier[2], &endptr, 0); else id = (unsigned char)simple_strtoul(identifier, &endptr, 0); /* * RFC 1994 says Identifier is no more than octet (8 bits). */ pr_debug("[server] Got CHAP_I=%d\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; } sg_init_one(&sg, (void *)&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, (void *)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, (void *)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 = (struct iscsi_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 = (struct iscsi_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; }