in iscsi/iscsi_target_auth.c [208:497]
static int chap_server_compute_hash(
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 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;
}
if (type != HEX) {
pr_err("Could not find CHAP_R.\n");
goto out;
}
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\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.
*/
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,
initiatorchg, &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;
}
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\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;
}