diff options
Diffstat (limited to 'drivers/target/iscsi/iscsi_target_auth.c')
| -rw-r--r-- | drivers/target/iscsi/iscsi_target_auth.c | 474 |
1 files changed, 474 insertions, 0 deletions
diff --git a/drivers/target/iscsi/iscsi_target_auth.c b/drivers/target/iscsi/iscsi_target_auth.c new file mode 100644 index 000000000..b6bf605fa --- /dev/null +++ b/drivers/target/iscsi/iscsi_target_auth.c @@ -0,0 +1,474 @@ +/******************************************************************************* + * 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 <crypto/hash.h> +#include <linux/kernel.h> +#include <linux/string.h> +#include <linux/err.h> +#include <linux/random.h> +#include <linux/scatterlist.h> +#include <target/iscsi/iscsi_target_core.h> +#include "iscsi_target_nego.h" +#include "iscsi_target_auth.h" + +static int chap_gen_challenge( + struct iscsi_conn *conn, + int caller, + char *c_str, + unsigned int *c_len) +{ + int ret; + 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); + + ret = get_random_bytes_wait(chap->challenge, CHAP_CHALLENGE_LENGTH); + if (unlikely(ret)) + return ret; + bin2hex(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); + return 0; +} + +static int chap_check_algorithm(const char *a_str) +{ + char *tmp, *orig, *token; + + tmp = kstrdup(a_str, GFP_KERNEL); + if (!tmp) { + pr_err("Memory allocation failed for CHAP_A temporary buffer\n"); + return CHAP_DIGEST_UNKNOWN; + } + orig = tmp; + + token = strsep(&tmp, "="); + if (!token) + goto out; + + if (strcmp(token, "CHAP_A")) { + pr_err("Unable to locate CHAP_A key\n"); + goto out; + } + while (token) { + token = strsep(&tmp, ","); + if (!token) + goto out; + + if (!strcmp(token, "5")) { + pr_debug("Selected MD5 Algorithm\n"); + kfree(orig); + return CHAP_DIGEST_MD5; + } + } +out: + kfree(orig); + return CHAP_DIGEST_UNKNOWN; +} + +static void chap_close(struct iscsi_conn *conn) +{ + kfree(conn->auth_protocol); + conn->auth_protocol = NULL; +} + +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) +{ + int ret; + 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; + ret = chap_check_algorithm(a_str); + switch (ret) { + case CHAP_DIGEST_MD5: + 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); + break; + case CHAP_DIGEST_UNKNOWN: + default: + pr_err("Unsupported CHAP_A value\n"); + chap_close(conn); + return NULL; + } + + /* + * 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. + */ + if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) { + chap_close(conn); + return NULL; + } + + return chap; +} + +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) +{ + 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_shash *tfm = NULL; + struct shash_desc *desc = NULL; + 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; + } + if (strlen(chap_r) != MD5_SIGNATURE_SIZE * 2) { + pr_err("Malformed CHAP_R\n"); + goto out; + } + if (hex2bin(client_digest, chap_r, MD5_SIGNATURE_SIZE) < 0) { + pr_err("Malformed CHAP_R\n"); + goto out; + } + + pr_debug("[server] Got CHAP_R=%s\n", chap_r); + + tfm = crypto_alloc_shash("md5", 0, 0); + if (IS_ERR(tfm)) { + tfm = NULL; + pr_err("Unable to allocate struct crypto_shash\n"); + goto out; + } + + desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL); + if (!desc) { + pr_err("Unable to allocate struct shash_desc\n"); + goto out; + } + + desc->tfm = tfm; + desc->flags = 0; + + ret = crypto_shash_init(desc); + if (ret < 0) { + pr_err("crypto_shash_init() failed\n"); + goto out; + } + + ret = crypto_shash_update(desc, &chap->id, 1); + if (ret < 0) { + pr_err("crypto_shash_update() failed for id\n"); + goto out; + } + + ret = crypto_shash_update(desc, (char *)&auth->password, + strlen(auth->password)); + if (ret < 0) { + pr_err("crypto_shash_update() failed for password\n"); + goto out; + } + + ret = crypto_shash_finup(desc, chap->challenge, + CHAP_CHALLENGE_LENGTH, server_digest); + if (ret < 0) { + pr_err("crypto_shash_finup() failed for challenge\n"); + goto out; + } + + bin2hex(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 connection" + " successful.\n\n"); + /* + * One way authentication has succeeded, return now if mutual + * authentication is not enabled. + */ + if (!auth->authenticate_target) { + auth_ret = 0; + goto out; + } + /* + * 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) + ret = kstrtoul(&identifier[2], 0, &id); + else + ret = kstrtoul(identifier, 0, &id); + + if (ret < 0) { + pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret); + goto out; + } + 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; + } + challenge_len = DIV_ROUND_UP(strlen(challenge), 2); + if (!challenge_len) { + pr_err("Unable to convert incoming challenge\n"); + goto out; + } + if (challenge_len > 1024) { + pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n"); + goto out; + } + if (hex2bin(challenge_binhex, challenge, challenge_len) < 0) { + pr_err("Malformed CHAP_C\n"); + goto out; + } + pr_debug("[server] Got CHAP_C=%s\n", challenge); + /* + * During mutual authentication, the CHAP_C generated by the + * initiator must not match the original CHAP_C generated by + * the target. + */ + if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) { + pr_err("initiator CHAP_C matches target CHAP_C, failing" + " login attempt\n"); + goto out; + } + /* + * Generate CHAP_N and CHAP_R for mutual authentication. + */ + ret = crypto_shash_init(desc); + if (ret < 0) { + pr_err("crypto_shash_init() failed\n"); + goto out; + } + + /* To handle both endiannesses */ + id_as_uchar = id; + ret = crypto_shash_update(desc, &id_as_uchar, 1); + if (ret < 0) { + pr_err("crypto_shash_update() failed for id\n"); + goto out; + } + + ret = crypto_shash_update(desc, auth->password_mutual, + strlen(auth->password_mutual)); + if (ret < 0) { + pr_err("crypto_shash_update() failed for" + " password_mutual\n"); + goto out; + } + /* + * Convert received challenge to binary hex. + */ + ret = crypto_shash_finup(desc, challenge_binhex, challenge_len, + digest); + if (ret < 0) { + pr_err("crypto_shash_finup() failed for ma challenge\n"); + goto out; + } + + /* + * 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. + */ + bin2hex(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: + kzfree(desc); + if (tfm) + crypto_free_shash(tfm); + 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; +} |