eap-sim: Updated EAP-SIM to use simauth module
This commit is contained in:
James Prestwood
Denis Kenzior
parent
a1ceb34bec
commit
80aa03edd8
283
src/eap-sim.c
283
src/eap-sim.c
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@ -31,8 +31,8 @@
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#include "crypto.h"
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#include "simutil.h"
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#include "simauth.h"
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#include "util.h"
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#include "src/dbus.h"
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/*
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* EAP-SIM authentication protocol.
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@ -64,8 +64,6 @@
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/* EAP-SIM value lengths */
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#define EAP_SIM_NONCE_LEN 16
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#define EAP_SIM_KC_LEN 8
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#define EAP_SIM_SRES_LEN 4
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/*
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* Internal client state, tracked to ensure that we are receiving the right
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@ -91,12 +89,6 @@ struct eap_sim_handle {
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/* Negotiated EAP-SIM version */
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uint16_t selected_version;
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/* RAND's from AT_RAND attribute */
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uint8_t rands[3][EAP_SIM_RAND_LEN];
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/* Kc values from SIM */
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uint8_t kc[3][EAP_SIM_KC_LEN];
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/* Random generated nonce */
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uint8_t nonce[EAP_SIM_NONCE_LEN];
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@ -115,24 +107,28 @@ struct eap_sim_handle {
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/* Derived EMSK from PRNG */
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uint8_t emsk[EAP_SIM_EMSK_LEN];
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/* SRES values from SIM */
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uint8_t sres[3][EAP_SIM_SRES_LEN];
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/* Flag set if AT_ANY_ID_REQ was present */
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bool any_id_req : 1;
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/* Flag to indicate protected status indications */
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bool protected : 1;
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uint8_t *chal_pkt;
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uint32_t pkt_len;
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struct iwd_sim_auth *auth;
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unsigned int auth_watch;
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};
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static void eap_sim_free(struct eap_state *eap)
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{
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struct eap_sim_handle *sim = eap_get_data(eap);
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if (sim->auth)
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sim_auth_unregistered_watch_remove(sim->auth, sim->auth_watch);
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l_free(sim->identity);
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l_free(sim->vlist);
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/* Kc values are crucial to security, zero them just in case */
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memset(sim->kc, 0, sizeof(sim->kc));
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l_free(sim);
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eap_set_data(eap, NULL);
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@ -284,6 +280,107 @@ start_error:
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eap_sim_client_error(eap, EAP_TYPE_SIM, EAP_SIM_ERROR_PROCESS);
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}
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static void gsm_callback(const uint8_t *sres, const uint8_t *kc,
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void *user_data)
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{
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struct eap_state *eap = user_data;
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struct eap_sim_handle *sim = eap_get_data(eap);
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uint16_t resp_len = 8 + 20;
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uint8_t response[resp_len + 4 + (EAP_SIM_SRES_LEN * 3)];
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uint8_t *pos = response;
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uint8_t prng_buf[160];
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uint8_t *mac_pos;
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if (!sres || !kc) {
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l_free(sim->chal_pkt);
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goto chal_error;
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}
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if (sim->protected)
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resp_len += 4;
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if (!derive_master_key(sim->identity, kc, sim->nonce, sim->vlist,
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sim->vlist_len, sim->selected_version, sim->mk)) {
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l_error("error deriving master key");
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goto chal_fatal;
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}
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eap_sim_fips_prf(sim->mk, 20, prng_buf, 160);
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if (!eap_sim_get_encryption_keys(prng_buf, sim->k_encr, sim->k_aut,
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sim->msk, sim->emsk)) {
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l_error("could not derive encryption keys");
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goto chal_fatal;
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}
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if (!eap_sim_verify_mac(eap, EAP_TYPE_SIM, sim->chal_pkt,
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sim->pkt_len, sim->k_aut, sim->nonce,
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EAP_SIM_NONCE_LEN)) {
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l_error("server MAC was invalid");
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l_free(sim->chal_pkt);
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goto chal_error;
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}
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sim->state = EAP_SIM_STATE_CHALLENGE;
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/*
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* TODO: When/If fast re-authentication is supported, the AT_ENCR_DATA
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* attribute would be decrypted here. Currently there is no need
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* or reason to do this without support for fast
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* re-authentication.
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*/
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/* build response packet */
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pos += eap_sim_build_header(eap, EAP_TYPE_SIM, EAP_SIM_ST_CHALLENGE,
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pos, resp_len);
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if (sim->protected)
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pos += eap_sim_add_attribute(pos, EAP_SIM_AT_RESULT_IND,
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EAP_SIM_PAD_NONE, NULL, 2);
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/* save MAC position to know where to write it to */
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mac_pos = pos;
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pos += eap_sim_add_attribute(pos, EAP_SIM_AT_MAC, EAP_SIM_PAD_NONE,
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NULL, EAP_SIM_MAC_LEN);
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/* append SRES for MAC derivation */
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memcpy(pos, sres, EAP_SIM_SRES_LEN * 3);
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pos += EAP_SIM_SRES_LEN * 3;
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if (!eap_sim_derive_mac(EAP_TYPE_SIM, response, pos - response,
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sim->k_aut, mac_pos + 4)) {
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l_error("could not derive MAC");
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goto chal_fatal;
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}
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l_free(sim->chal_pkt);
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eap_send_response(eap, EAP_TYPE_SIM, response, resp_len);
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if (!sim->protected) {
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/*
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* Result indication not required, we must accept success.
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*/
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eap_method_success(eap);
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eap_set_key_material(eap, sim->msk, 32, NULL, 0, NULL, 0);
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sim->state = EAP_SIM_STATE_SUCCESS;
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}
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return;
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/*
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* fatal, unrecoverable error
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*/
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chal_fatal:
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eap_method_error(eap);
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sim->state = EAP_SIM_STATE_ERROR;
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return;
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chal_error:
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eap_sim_client_error(eap, EAP_TYPE_SIM, EAP_SIM_ERROR_PROCESS);
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}
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/*
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* Handles EAP-SIM Challenge subtype
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*/
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@ -293,17 +390,8 @@ static void handle_challenge(struct eap_state *eap, const uint8_t *pkt,
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struct eap_sim_handle *sim = eap_get_data(eap);
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struct eap_sim_tlv_iter iter;
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enum eap_sim_error code = EAP_SIM_ERROR_PROCESS;
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/* header + AT_MAC */
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uint16_t resp_len = 8 + 20;
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/*
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* The response buf adds SRES*3 for MAC derivation + the response
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* indicator, which is not always present.
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* (resp_len gets incremented only if AT_RESPONSE_IND is present)
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*/
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uint8_t response[resp_len + 4 + (EAP_SIM_SRES_LEN * 3)];
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uint8_t *pos = response;
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uint8_t prng_buf[160];
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uint8_t *mac_pos;
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const uint8_t *rands = NULL;
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if (sim->state != EAP_SIM_STATE_START) {
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l_error("invalid packet for EAP-SIM state");
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@ -334,12 +422,11 @@ static void handle_challenge(struct eap_state *eap, const uint8_t *pkt,
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* should only exist if we are re-authenticating to the
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* server, which is currently not implemented.
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*/
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memcpy(sim->rands, contents + 2, length - 2);
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rands = contents + 2;
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break;
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case EAP_SIM_AT_RESULT_IND:
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sim->protected = true;
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resp_len += 4;
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break;
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case EAP_SIM_AT_IV:
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@ -355,78 +442,14 @@ static void handle_challenge(struct eap_state *eap, const uint8_t *pkt,
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}
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}
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if (!derive_master_key(sim->identity, sim->kc, sim->nonce, sim->vlist,
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sim->vlist_len, sim->selected_version, sim->mk)) {
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l_error("error deriving master key");
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goto chal_fatal;
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}
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sim->chal_pkt = l_memdup(pkt, len);
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sim->pkt_len = len;
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eap_sim_fips_prf(sim->mk, 20, prng_buf, 160);
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if (!eap_sim_get_encryption_keys(prng_buf, sim->k_encr, sim->k_aut,
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sim->msk, sim->emsk)) {
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l_error("could not derive encryption keys");
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goto chal_fatal;
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}
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if (!eap_sim_verify_mac(eap, EAP_TYPE_SIM, pkt, len, sim->k_aut,
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sim->nonce, EAP_SIM_NONCE_LEN)) {
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l_error("server MAC was invalid");
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if (sim_auth_run_gsm(sim->auth, rands, 3, gsm_callback, eap) < 0) {
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l_free(sim->chal_pkt);
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goto chal_error;
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}
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sim->state = EAP_SIM_STATE_CHALLENGE;
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/*
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* TODO: When/If fast re-authentication is supported, the AT_ENCR_DATA
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* attribute would be decrypted here. Currently there is no need
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* or reason to do this without support for fast
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* re-authentication.
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*/
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/* build response packet */
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pos += eap_sim_build_header(eap, EAP_TYPE_SIM, EAP_SIM_ST_CHALLENGE,
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pos, resp_len);
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if (sim->protected)
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pos += eap_sim_add_attribute(pos, EAP_SIM_AT_RESULT_IND,
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EAP_SIM_PAD_NONE, NULL, 2);
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/* save MAC position to know where to write it to */
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mac_pos = pos;
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pos += eap_sim_add_attribute(pos, EAP_SIM_AT_MAC, EAP_SIM_PAD_NONE,
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NULL, EAP_SIM_MAC_LEN);
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/* append SRES for MAC derivation */
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memcpy(pos, sim->sres, EAP_SIM_SRES_LEN * 3);
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pos += EAP_SIM_SRES_LEN * 3;
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if (!eap_sim_derive_mac(EAP_TYPE_SIM, response, pos - response,
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sim->k_aut, mac_pos + 4)) {
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l_error("could not derive MAC");
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goto chal_fatal;
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}
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eap_send_response(eap, EAP_TYPE_SIM, response, resp_len);
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if (!sim->protected) {
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/*
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* Result indication not required, we must accept success.
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*/
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eap_method_success(eap);
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eap_set_key_material(eap, sim->msk, 32, NULL, 0, NULL, 0);
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sim->state = EAP_SIM_STATE_SUCCESS;
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}
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return;
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/*
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* fatal, unrecoverable error
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*/
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chal_fatal:
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eap_method_error(eap);
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sim->state = EAP_SIM_STATE_ERROR;
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return;
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chal_error:
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@ -559,48 +582,55 @@ req_error:
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eap_sim_client_error(eap, EAP_TYPE_SIM, EAP_SIM_ERROR_PROCESS);
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}
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static const char *eap_sim_get_identity(struct eap_state *eap)
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{
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struct eap_sim_handle *sim = eap_get_data(eap);
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return sim->identity;
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}
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static void auth_destroyed(void *data)
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{
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struct eap_state *eap = data;
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struct eap_sim_handle *sim = eap_get_data(eap);
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/*
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* If AKA was already successful we can return. Also if the state
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* has been set to ERROR, then eap_method_error has already been called,
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* so we can return.
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*/
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if (sim->state == EAP_SIM_STATE_SUCCESS ||
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sim->state == EAP_SIM_STATE_ERROR)
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return;
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l_error("auth provider destroyed before SIM could finish");
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sim->state = EAP_SIM_STATE_ERROR;
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eap_method_error(eap);
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}
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static bool eap_sim_load_settings(struct eap_state *eap,
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struct l_settings *settings,
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const char *prefix)
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{
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struct eap_sim_handle *sim;
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char setting[64];
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const char *kcs;
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const char *imsi;
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const char *sres;
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size_t len;
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/*
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* No specific settings for EAP-SIM, the auth provider will have all
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* required data.
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*/
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sim = l_new(struct eap_sim_handle, 1);
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eap_set_data(eap, sim);
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/*
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* TODO: These values will be loaded from a SIM card. Kc and SRES
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* values should be kept secret and crucial to the security of EAP-SIM.
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* It may be better to load them on the fly (from the SIM) as needed
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* rather than storing them in the eap_sim_state structure.
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*/
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snprintf(setting, sizeof(setting), "%sSIM-Kc", prefix);
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kcs = l_settings_get_value(settings, "Security", setting);
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if (kcs) {
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uint8_t *val = l_util_from_hexstring(kcs, &len);
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memcpy(sim->kc, val, len);
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l_free(val);
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sim->auth = iwd_sim_auth_find(true, false);
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if (!sim->auth) {
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l_debug("no SIM driver available for %s", sim->identity);
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return false;
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}
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snprintf(setting, sizeof(setting), "%sSIM-IMSI", prefix);
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imsi = l_settings_get_value(settings, "Security", setting);
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if (imsi)
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sim->identity = l_strdup(imsi);
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snprintf(setting, sizeof(setting), "%sSIM-SRES", prefix);
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sres = l_settings_get_value(settings, "Security", setting);
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if (sres) {
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uint8_t *val = l_util_from_hexstring(sres, &len);
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memcpy(sim->sres, val, len);
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l_free(val);
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}
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sim->auth_watch = sim_auth_unregistered_watch_add(sim->auth,
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auth_destroyed, eap);
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sim->identity = l_strdup(iwd_sim_auth_get_nai(sim->auth));
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return true;
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}
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@ -612,6 +642,7 @@ static struct eap_method eap_sim = {
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.free = eap_sim_free,
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.handle_request = eap_sim_handle_request,
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.load_settings = eap_sim_load_settings,
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.get_identity = eap_sim_get_identity
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};
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static int eap_sim_init(void)
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