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;
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);
return 0;
}
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_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;
}
/* 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;
}
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, &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, &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, 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)
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;
}
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;
}
if (challenge_len > 1024) {
pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
goto out;
}
/*
* 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;
}
/*
* 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.
*/
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;
}
/* To handle both endiannesses */
id_as_uchar = id;
sg_init_one(&sg, &id_as_uchar, 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, 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, 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;
}
