diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/target/iscsi/iscsi_target_auth.c | 603 |
1 files changed, 603 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..c8a248bd1 --- /dev/null +++ b/drivers/target/iscsi/iscsi_target_auth.c @@ -0,0 +1,603 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/******************************************************************************* + * 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> + * + ******************************************************************************/ + +#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 char *chap_get_digest_name(const int digest_type) +{ + switch (digest_type) { + case CHAP_DIGEST_MD5: + return "md5"; + case CHAP_DIGEST_SHA1: + return "sha1"; + case CHAP_DIGEST_SHA256: + return "sha256"; + case CHAP_DIGEST_SHA3_256: + return "sha3-256"; + default: + return NULL; + } +} + +static int chap_gen_challenge( + struct iscsit_conn *conn, + int caller, + char *c_str, + unsigned int *c_len) +{ + int ret; + unsigned char *challenge_asciihex; + struct iscsi_chap *chap = conn->auth_protocol; + + challenge_asciihex = kzalloc(chap->challenge_len * 2 + 1, GFP_KERNEL); + if (!challenge_asciihex) + return -ENOMEM; + + memset(chap->challenge, 0, MAX_CHAP_CHALLENGE_LEN); + + ret = get_random_bytes_wait(chap->challenge, chap->challenge_len); + if (unlikely(ret)) + goto out; + + bin2hex(challenge_asciihex, chap->challenge, + chap->challenge_len); + /* + * 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); + +out: + kfree(challenge_asciihex); + return ret; +} + +static int chap_test_algorithm(const char *name) +{ + struct crypto_shash *tfm; + + tfm = crypto_alloc_shash(name, 0, 0); + if (IS_ERR(tfm)) + return -1; + + crypto_free_shash(tfm); + return 0; +} + +static int chap_check_algorithm(const char *a_str) +{ + char *tmp, *orig, *token, *digest_name; + long digest_type; + int r = CHAP_DIGEST_UNKNOWN; + + 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 (kstrtol(token, 10, &digest_type)) + continue; + + digest_name = chap_get_digest_name(digest_type); + if (!digest_name) + continue; + + pr_debug("Selected %s Algorithm\n", digest_name); + if (chap_test_algorithm(digest_name) < 0) { + pr_err("failed to allocate %s algo\n", digest_name); + } else { + r = digest_type; + goto out; + } + } +out: + kfree(orig); + return r; +} + +static void chap_close(struct iscsit_conn *conn) +{ + kfree(conn->auth_protocol); + conn->auth_protocol = NULL; +} + +static struct iscsi_chap *chap_server_open( + struct iscsit_conn *conn, + struct iscsi_node_auth *auth, + const char *a_str, + char *aic_str, + unsigned int *aic_len) +{ + int digest_type; + 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; + digest_type = chap_check_algorithm(a_str); + switch (digest_type) { + case CHAP_DIGEST_MD5: + chap->digest_size = MD5_SIGNATURE_SIZE; + break; + case CHAP_DIGEST_SHA1: + chap->digest_size = SHA1_SIGNATURE_SIZE; + break; + case CHAP_DIGEST_SHA256: + chap->digest_size = SHA256_SIGNATURE_SIZE; + break; + case CHAP_DIGEST_SHA3_256: + chap->digest_size = SHA3_256_SIGNATURE_SIZE; + break; + case CHAP_DIGEST_UNKNOWN: + default: + pr_err("Unsupported CHAP_A value\n"); + chap_close(conn); + return NULL; + } + + chap->digest_name = chap_get_digest_name(digest_type); + + /* Tie the challenge length to the digest size */ + chap->challenge_len = chap->digest_size; + + pr_debug("[server] Got CHAP_A=%d\n", digest_type); + *aic_len = sprintf(aic_str, "CHAP_A=%d", digest_type); + *aic_len += 1; + pr_debug("[server] Sending CHAP_A=%d\n", 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. + */ + if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) { + chap_close(conn); + return NULL; + } + + return chap; +} + +static const char base64_lookup_table[] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +static int chap_base64_decode(u8 *dst, const char *src, size_t len) +{ + int i, bits = 0, ac = 0; + const char *p; + u8 *cp = dst; + + for (i = 0; i < len; i++) { + if (src[i] == '=') + return cp - dst; + + p = strchr(base64_lookup_table, src[i]); + if (p == NULL || src[i] == 0) + return -2; + + ac <<= 6; + ac += (p - base64_lookup_table); + bits += 6; + if (bits >= 8) { + *cp++ = (ac >> (bits - 8)) & 0xff; + ac &= ~(BIT(16) - BIT(bits - 8)); + bits -= 8; + } + } + if (ac) + return -1; + + return cp - dst; +} + +static int chap_server_compute_hash( + struct iscsit_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 type; + unsigned char identifier[10], *initiatorchg = NULL; + unsigned char *initiatorchg_binhex = NULL; + unsigned char *digest = NULL; + unsigned char *response = NULL; + unsigned char *client_digest = NULL; + unsigned char *server_digest = NULL; + 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, initiatorchg_len; + + digest = kzalloc(chap->digest_size, GFP_KERNEL); + if (!digest) { + pr_err("Unable to allocate the digest buffer\n"); + goto out; + } + + response = kzalloc(chap->digest_size * 2 + 2, GFP_KERNEL); + if (!response) { + pr_err("Unable to allocate the response buffer\n"); + goto out; + } + + client_digest = kzalloc(chap->digest_size, GFP_KERNEL); + if (!client_digest) { + pr_err("Unable to allocate the client_digest buffer\n"); + goto out; + } + + server_digest = kzalloc(chap->digest_size, GFP_KERNEL); + if (!server_digest) { + pr_err("Unable to allocate the server_digest buffer\n"); + goto out; + } + + memset(identifier, 0, 10); + memset(chap_n, 0, MAX_CHAP_N_SIZE); + memset(chap_r, 0, MAX_RESPONSE_LENGTH); + + initiatorchg = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); + if (!initiatorchg) { + pr_err("Unable to allocate challenge buffer\n"); + goto out; + } + + initiatorchg_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); + if (!initiatorchg_binhex) { + pr_err("Unable to allocate initiatorchg_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; + } + + switch (type) { + case HEX: + if (strlen(chap_r) != chap->digest_size * 2) { + pr_err("Malformed CHAP_R\n"); + goto out; + } + if (hex2bin(client_digest, chap_r, chap->digest_size) < 0) { + pr_err("Malformed CHAP_R: invalid HEX\n"); + goto out; + } + break; + case BASE64: + if (chap_base64_decode(client_digest, chap_r, strlen(chap_r)) != + chap->digest_size) { + pr_err("Malformed CHAP_R: invalid BASE64\n"); + goto out; + } + break; + default: + pr_err("Could not find CHAP_R\n"); + goto out; + } + + pr_debug("[server] Got CHAP_R=%s\n", chap_r); + + tfm = crypto_alloc_shash(chap->digest_name, 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; + + 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_len, server_digest); + if (ret < 0) { + pr_err("crypto_shash_finup() failed for challenge\n"); + goto out; + } + + bin2hex(response, server_digest, chap->digest_size); + pr_debug("[server] %s Server Digest: %s\n", + chap->digest_name, response); + + if (memcmp(server_digest, client_digest, chap->digest_size) != 0) { + pr_debug("[server] %s Digests do not match!\n\n", + chap->digest_name); + goto out; + } else + pr_debug("[server] %s Digests match, CHAP connection" + " successful.\n\n", chap->digest_name); + /* + * 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. + */ + ret = extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type); + if (ret == -ENOENT) { + pr_debug("Could not find CHAP_I. Initiator uses One way authentication.\n"); + auth_ret = 0; + goto out; + } + if (ret < 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, + initiatorchg, &type) < 0) { + pr_err("Could not find CHAP_C.\n"); + goto out; + } + + switch (type) { + case HEX: + initiatorchg_len = DIV_ROUND_UP(strlen(initiatorchg), 2); + if (!initiatorchg_len) { + pr_err("Unable to convert incoming challenge\n"); + goto out; + } + if (initiatorchg_len > 1024) { + pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n"); + goto out; + } + + if (hex2bin(initiatorchg_binhex, initiatorchg, + initiatorchg_len) < 0) { + pr_err("Malformed CHAP_C: invalid HEX\n"); + goto out; + } + break; + case BASE64: + initiatorchg_len = chap_base64_decode(initiatorchg_binhex, + initiatorchg, + strlen(initiatorchg)); + if (initiatorchg_len < 0) { + pr_err("Malformed CHAP_C: invalid BASE64\n"); + goto out; + } + if (!initiatorchg_len) { + pr_err("Unable to convert incoming challenge\n"); + goto out; + } + if (initiatorchg_len > 1024) { + pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n"); + goto out; + } + break; + default: + pr_err("Could not find CHAP_C.\n"); + goto out; + } + + pr_debug("[server] Got CHAP_C=%s\n", initiatorchg); + /* + * During mutual authentication, the CHAP_C generated by the + * initiator must not match the original CHAP_C generated by + * the target. + */ + if (initiatorchg_len == chap->challenge_len && + !memcmp(initiatorchg_binhex, chap->challenge, + initiatorchg_len)) { + 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, initiatorchg_binhex, initiatorchg_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, chap->digest_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_sensitive(desc); + if (tfm) + crypto_free_shash(tfm); + kfree(initiatorchg); + kfree(initiatorchg_binhex); + kfree(digest); + kfree(response); + kfree(server_digest); + kfree(client_digest); + return auth_ret; +} + +u32 chap_main_loop( + struct iscsit_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_server_compute_hash(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; +} |