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EAP-SIM: Add Session-Id derivation during fast-reauth

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The Session-Id derivation for EAP-SIM in RFC 5247 only explained how the
Session-Id is derived for regular authentication. Jouni reported it as
an errata with text explaining how to derive it during fast
reauthentication.

This patch now exports the Session-Id for EAP-SIM during fast
reauthentication based on this Session-Id = 0x12 || NONCE_S || MAC
construction.

Signed-off-by: Mohit Sethi <mohit.sethi@aalto.fi>
This commit is contained in:
Mohit Sethi 2019-05-17 14:40:30 +03:00 committed by Jouni Malinen
parent 2f6700c9c6
commit 1c16b257a0
2 changed files with 48 additions and 9 deletions
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26
src/eap_peer/eap_sim.c
View file

@ -32,6 +32,7 @@ struct eap_sim_data {
u8 msk[EAP_SIM_KEYING_DATA_LEN];
u8 emsk[EAP_EMSK_LEN];
u8 rand[3][GSM_RAND_LEN];
u8 reauth_mac[EAP_SIM_MAC_LEN];
int num_id_req, num_notification;
u8 *pseudonym;
@ -958,6 +959,14 @@ static struct wpabuf * eap_sim_process_reauthentication(
EAP_SIM_UNABLE_TO_PROCESS_PACKET);
}
/* At this stage the received MAC has been verified. Use this MAC for
* reauth Session-Id calculation if all other checks pass.
* The peer does not use the local MAC but the received MAC in deriving
* Session-Id. */
os_memcpy(data->reauth_mac, attr->mac, EAP_SIM_MAC_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-SIM: Server MAC",
data->reauth_mac, EAP_SIM_MAC_LEN);
if (attr->encr_data == NULL || attr->iv == NULL) {
wpa_printf(MSG_WARNING, "EAP-SIM: Reauthentication "
"message did not include encrypted data");
@ -1216,15 +1225,24 @@ static u8 * eap_sim_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
if (data->state != SUCCESS)
return NULL;
*len = 1 + data->num_chal * GSM_RAND_LEN + EAP_SIM_NONCE_MT_LEN;
if (!data->reauth)
*len = 1 + data->num_chal * GSM_RAND_LEN + EAP_SIM_NONCE_MT_LEN;
else
*len = 1 + EAP_SIM_NONCE_S_LEN + EAP_SIM_MAC_LEN;
id = os_malloc(*len);
if (id == NULL)
return NULL;
id[0] = EAP_TYPE_SIM;
os_memcpy(id + 1, data->rand, data->num_chal * GSM_RAND_LEN);
os_memcpy(id + 1 + data->num_chal * GSM_RAND_LEN, data->nonce_mt,
EAP_SIM_NONCE_MT_LEN);
if (!data->reauth) {
os_memcpy(id + 1, data->rand, data->num_chal * GSM_RAND_LEN);
os_memcpy(id + 1 + data->num_chal * GSM_RAND_LEN,
data->nonce_mt, EAP_SIM_NONCE_MT_LEN);
} else {
os_memcpy(id + 1, data->nonce_s, EAP_SIM_NONCE_S_LEN);
os_memcpy(id + 1 + EAP_SIM_NONCE_S_LEN, data->reauth_mac,
EAP_SIM_MAC_LEN);
}
wpa_hexdump(MSG_DEBUG, "EAP-SIM: Derived Session-Id", id, *len);
return id;

31
src/eap_server/eap_server_sim.c
View file

@ -26,6 +26,7 @@ struct eap_sim_data {
u8 kc[EAP_SIM_MAX_CHAL][EAP_SIM_KC_LEN];
u8 sres[EAP_SIM_MAX_CHAL][EAP_SIM_SRES_LEN];
u8 rand[EAP_SIM_MAX_CHAL][GSM_RAND_LEN];
u8 reauth_mac[EAP_SIM_MAC_LEN];
int num_chal;
enum {
START, CHALLENGE, REAUTH, NOTIFICATION, SUCCESS, FAILURE
@ -249,6 +250,7 @@ static struct wpabuf * eap_sim_build_reauth(struct eap_sm *sm,
struct eap_sim_data *data, u8 id)
{
struct eap_sim_msg *msg;
struct wpabuf *buf;
wpa_printf(MSG_DEBUG, "EAP-SIM: Generating Re-authentication");
@ -278,7 +280,16 @@ static struct wpabuf * eap_sim_build_reauth(struct eap_sm *sm,
wpa_printf(MSG_DEBUG, " AT_MAC");
eap_sim_msg_add_mac(msg, EAP_SIM_AT_MAC);
return eap_sim_msg_finish(msg, EAP_TYPE_SIM, data->k_aut, NULL, 0);
buf = eap_sim_msg_finish(msg, EAP_TYPE_SIM, data->k_aut, NULL, 0);
/* Remember this MAC before sending it to the peer. This MAC is used for
* Session-Id calculation after receiving response from the peer and
* after all other checks pass. */
os_memcpy(data->reauth_mac,
wpabuf_head(buf) + wpabuf_len(buf) - EAP_SIM_MAC_LEN,
EAP_SIM_MAC_LEN);
return buf;
}
@ -829,15 +840,25 @@ static u8 * eap_sim_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
if (data->state != SUCCESS)
return NULL;
*len = 1 + data->num_chal * GSM_RAND_LEN + EAP_SIM_NONCE_MT_LEN;
if (!data->reauth)
*len = 1 + data->num_chal * GSM_RAND_LEN + EAP_SIM_NONCE_MT_LEN;
else
*len = 1 + EAP_SIM_NONCE_S_LEN + EAP_SIM_MAC_LEN;
id = os_malloc(*len);
if (id == NULL)
return NULL;
id[0] = EAP_TYPE_SIM;
os_memcpy(id + 1, data->rand, data->num_chal * GSM_RAND_LEN);
os_memcpy(id + 1 + data->num_chal * GSM_RAND_LEN, data->nonce_mt,
EAP_SIM_NONCE_MT_LEN);
if (!data->reauth) {
os_memcpy(id + 1, data->rand, data->num_chal * GSM_RAND_LEN);
os_memcpy(id + 1 + data->num_chal * GSM_RAND_LEN,
data->nonce_mt, EAP_SIM_NONCE_MT_LEN);
} else {
os_memcpy(id + 1, data->nonce_s, EAP_SIM_NONCE_S_LEN);
os_memcpy(id + 1 + EAP_SIM_NONCE_S_LEN, data->reauth_mac,
EAP_SIM_MAC_LEN);
}
wpa_hexdump(MSG_DEBUG, "EAP-SIM: Derived Session-Id", id, *len);
return id;