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sim: EAP-SIM protocol implementation

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This commit is contained in:
James Prestwood 2017-08-21 14:09:03 -07:00 committed by Denis Kenzior
parent e6765c1e9b
commit 283717b22f
5 changed files with 1237 additions and 1 deletions
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3
Makefile.am
View File

@ -86,7 +86,8 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h \
src/rfkill.h src/rfkill.c \
src/watchlist.h src/watchlist.c \
src/ftutil.h src/ftutil.c \
src/iwd.h
src/iwd.h src/eap-sim.c \
src/simutil.h src/simutil.c
src_iwd_LDADD = ell/libell-internal.la -ldl
dist_sysconf_DATA = src/iwd.conf

644
src/eap-sim.c Normal file
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@ -0,0 +1,644 @@
/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2017 Intel Corporation. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <ctype.h>
#include <stdio.h>
#include <errno.h>
#include <ell/ell.h>
#include "crypto.h"
#include "simutil.h"
#include "src/dbus.h"
/*
* EAP-SIM authentication protocol.
*
* Open Items:
* - Fast Re-authentication. In order to implement this, the higher level
* EAP code would need to know/retrieve a fast re-authentication identity
* that it would send in the EAP-Start packet. This ID is provided by
* the server during the challenge in full authentication. EAP-SIM does
* save this ID, but there is no mechanism to provide it to the upper
* level EAP system. Once this is done the server will recognize the
* ID and send a SIM/Re-authentication request.
*
* - Version validation. Perhaps a real SIM card will provide a version
* of EAP-SIM that it supports? Currently we accept any version the
* server provides.
*
* - Real SIM authentication. Right now Kc/SRES/Identity values are loaded
* from a settings file. If a real SIM is used they would need to be
* obtained there. This would require providing the SIM with a RAND, to
* have it run its GSM algorithm. Kc/SRES can then be derived from that.
*/
/* RFC 4187, Section 11 */
#define EAP_SIM_ST_START 0x0a
#define EAP_SIM_ST_CHALLENGE 0x0b
#define EAP_SIM_ST_NOTIFICATION 0x0c
#define EAP_SIM_ST_CLIENT_ERROR 0x0e
/* EAP-SIM value lengths */
#define EAP_SIM_NONCE_LEN 16
#define EAP_SIM_KC_LEN 8
#define EAP_SIM_SRES_LEN 4
/*
* Internal client state, tracked to ensure that we are receiving the right
* messages at the right time.
*/
enum eap_sim_state {
EAP_SIM_STATE_UNCONNECTED = 0,
EAP_SIM_STATE_START,
EAP_SIM_STATE_CHALLENGE,
EAP_SIM_STATE_SUCCESS,
EAP_SIM_STATE_ERROR
};
struct eap_sim_handle {
enum eap_sim_state state;
/* Identity from SIM */
char *identity;
/* EAP-SIM supported version list */
uint16_t *vlist;
uint16_t vlist_len;
/* Negotiated EAP-SIM version */
uint16_t selected_version;
/* RAND's from AT_RAND attribute */
uint8_t rands[3][EAP_SIM_RAND_LEN];
/* Kc values from SIM */
uint8_t kc[3][EAP_SIM_KC_LEN];
/* Random generated nonce */
uint8_t nonce[EAP_SIM_NONCE_LEN];
/* Derived master key */
uint8_t mk[EAP_SIM_MK_LEN];
/* Derived K_encr key from PRNG */
uint8_t k_encr[EAP_SIM_K_ENCR_LEN];
/* Derived K_aut key from PRNG */
uint8_t k_aut[EAP_SIM_K_AUT_LEN];
/* Derived MSK from PRNG */
uint8_t msk[EAP_SIM_MSK_LEN];
/* Derived EMSK from PRNG */
uint8_t emsk[EAP_SIM_EMSK_LEN];
/* SRES values from SIM */
uint8_t sres[3][EAP_SIM_SRES_LEN];
/* Flag set if AT_ANY_ID_REQ was present */
bool any_id_req : 1;
/* Flag to indicate protected status indications */
bool protected : 1;
};
static int eap_sim_probe(struct eap_state *eap, const char *name)
{
struct eap_sim_handle *sim;
if (strcasecmp(name, "SIM"))
return -ENOTSUP;
sim = l_new(struct eap_sim_handle, 1);
eap_set_data(eap, sim);
return 0;
}
static void eap_sim_remove(struct eap_state *eap)
{
struct eap_sim_handle *sim = eap_get_data(eap);
l_free(sim->identity);
l_free(sim->vlist);
/* Kc values are crucial to security, zero them just in case */
memset(sim->kc, 0, sizeof(sim->kc));
l_free(sim);
eap_set_data(eap, NULL);
}
/*
* Derive the master key (MK):
* SHA1(identity | kc | nonce | version list | selected version)
*/
static bool derive_master_key(const char *identity, const void *kc,
const void *nonce, const void *vlist, uint16_t vlist_len,
uint16_t selected_version, uint8_t *mk)
{
int ret;
struct iovec iov[5];
struct l_checksum *checksum = l_checksum_new(L_CHECKSUM_SHA1);
if (!checksum) {
l_error("could not create SHA1 checksum");
return false;
}
iov[0].iov_base = (void *)identity;
iov[0].iov_len = strlen(identity);
iov[1].iov_base = (void *)kc;
iov[1].iov_len = EAP_SIM_KC_LEN * 3;
iov[2].iov_base = (void *)nonce;
iov[2].iov_len = EAP_SIM_NONCE_LEN;
iov[3].iov_base = (void *)vlist;
iov[3].iov_len = vlist_len;
iov[4].iov_base = &selected_version;
iov[4].iov_len = 2;
if (!l_checksum_updatev(checksum, iov, 5))
goto mk_error;
ret = l_checksum_get_digest(checksum, mk, EAP_SIM_MK_LEN);
l_checksum_free(checksum);
return (ret == EAP_SIM_MK_LEN);
mk_error:
l_checksum_free(checksum);
l_error("error deriving master key");
return false;
}
/*
* Handles EAP-SIM Start subtype
*/
static void handle_start(struct eap_state *eap, const uint8_t *pkt,
size_t len)
{
struct eap_sim_handle *sim = eap_get_data(eap);
struct eap_sim_tlv_iter iter;
uint16_t resp_len;
uint8_t *response;
uint8_t *pos;
if (len < 3) {
l_error("packet is too small");
goto start_error;
}
if (sim->state != EAP_SIM_STATE_UNCONNECTED) {
l_error("invalid packet for EAP-SIM state");
goto start_error;
}
eap_sim_tlv_iter_init(&iter, pkt + 3, len - 3);
while (eap_sim_tlv_iter_next(&iter)) {
const uint8_t *contents = eap_sim_tlv_iter_get_data(&iter);
uint16_t length = eap_sim_tlv_iter_get_length(&iter);
switch (eap_sim_tlv_iter_get_type(&iter)) {
case EAP_SIM_AT_VERSION_LIST:
if (length < 2) {
l_error("AT_VERSION_LIST was malformed");
goto start_error;
}
sim->vlist_len = l_get_be16(contents);
if (length < 2 + sim->vlist_len) {
l_error("AT_VERSION_LIST was malformed");
goto start_error;
}
/*
* The version list is stored as-is (including
* padding). This does mean that there is potential
* for padding bytes at the end, but this is expected
* when generating the Master Key.
*/
sim->vlist = l_memdup(contents + 2, sim->vlist_len);
sim->selected_version = sim->vlist[0];
break;
case EAP_SIM_AT_ANY_ID_REQ:
sim->any_id_req = true;
break;
case EAP_SIM_AT_PERMANENT_ID_REQ:
case EAP_SIM_AT_FULLAUTH_ID_REQ:
/*
* TODO: Server requesting permanent ID/pseudonym
*/
break;
default:
l_error("attribute %u was found in Start",
eap_sim_tlv_iter_get_type(&iter));
goto start_error;
}
}
sim->state = EAP_SIM_STATE_START;
/* header + AT_NONCE + AT_SELECTED_VERSION */
resp_len = (8) + (20) + (4);
if (sim->any_id_req) {
/* + AT_IDENTITY */
resp_len += EAP_SIM_ROUND(strlen(sim->identity) + 4);
}
l_getrandom(sim->nonce, EAP_SIM_NONCE_LEN);
response = alloca(resp_len);
pos = response;
pos += eap_sim_build_header(eap, EAP_TYPE_SIM, EAP_SIM_ST_START, pos,
resp_len);
pos += eap_sim_add_attribute(pos, EAP_SIM_AT_NONCE, EAP_SIM_PAD_ZERO,
sim->nonce, EAP_SIM_NONCE_LEN);
pos += eap_sim_add_attribute(pos, EAP_SIM_AT_SELECTED_VERSION,
EAP_SIM_PAD_NONE, (uint8_t *)&sim->selected_version,
2);
if (sim->any_id_req)
pos += eap_sim_add_attribute(pos, EAP_SIM_AT_IDENTITY,
EAP_SIM_PAD_LENGTH, (uint8_t *)sim->identity,
strlen(sim->identity));
eap_send_response(eap, EAP_TYPE_SIM, response, resp_len);
return;
start_error:
eap_sim_client_error(eap, EAP_TYPE_SIM, EAP_SIM_ERROR_PROCESS);
}
/*
* Handles EAP-SIM Challenge subtype
*/
static void handle_challenge(struct eap_state *eap, const uint8_t *pkt,
size_t len)
{
struct eap_sim_handle *sim = eap_get_data(eap);
struct eap_sim_tlv_iter iter;
enum eap_sim_error code = EAP_SIM_ERROR_PROCESS;
/* header + AT_MAC */
uint16_t resp_len = 8 + 20;
/*
* The response buf adds SRES*3 for MAC derivation + the response
* indicator, which is not always present.
* (resp_len gets incremented only if AT_RESPONSE_IND is present)
*/
uint8_t response[resp_len + 4 + (EAP_SIM_SRES_LEN * 3)];
uint8_t *pos = response;
uint8_t prng_buf[160];
uint8_t *mac_pos;
if (sim->state != EAP_SIM_STATE_START) {
l_error("invalid packet for EAP-SIM state");
goto chal_error;
}
if (len < 3) {
l_error("packet is too small");
goto chal_error;
}
eap_sim_tlv_iter_init(&iter, pkt + 3, len - 3);
while (eap_sim_tlv_iter_next(&iter)) {
const uint8_t *contents = eap_sim_tlv_iter_get_data(&iter);
uint16_t length = eap_sim_tlv_iter_get_length(&iter);
switch (eap_sim_tlv_iter_get_type(&iter)) {
case EAP_SIM_AT_RAND:
if ((length - 2) / 16 != 3) {
l_error("insufficient RAND's %u",
(length - 2) / 16);
code = EAP_SIM_ERROR_CHALLENGE;
goto chal_error;
}
/*
* TODO: check that RAND's are fresh. Existing RAND's
* should only exist if we are re-authenticating to the
* server, which is currently not implemented.
*/
memcpy(sim->rands, contents + 2, length - 2);
break;
case EAP_SIM_AT_RESULT_IND:
sim->protected = true;
resp_len += 4;
break;
case EAP_SIM_AT_IV:
case EAP_SIM_AT_ENCR_DATA:
case EAP_SIM_AT_MAC:
/* need a case for these so the default wont get hit */
break;
default:
l_error("attribute type %u not allowed in Challenge",
eap_sim_tlv_iter_get_type(&iter));
goto chal_error;
}
}
if (!derive_master_key(sim->identity, sim->kc, sim->nonce, sim->vlist,
sim->vlist_len, sim->selected_version, sim->mk)) {
l_error("error deriving master key");
goto chal_fatal;
}
eap_sim_fips_prf(sim->mk, 20, prng_buf, 160);
if (!eap_sim_get_encryption_keys(prng_buf, sim->k_encr, sim->k_aut,
sim->msk, sim->emsk)) {
l_error("could not derive encryption keys");
goto chal_fatal;
}
if (!eap_sim_verify_mac(eap, EAP_TYPE_SIM, pkt, len, sim->k_aut,
sim->nonce, EAP_SIM_NONCE_LEN)) {
l_error("server MAC was invalid");
goto chal_error;
}
sim->state = EAP_SIM_STATE_CHALLENGE;
/*
* TODO: When/If fast re-authentication is supported, the AT_ENCR_DATA
* attribute would be decrypted here. Currently there is no need
* or reason to do this without support for fast
* re-authentication.
*/
/* build response packet */
pos += eap_sim_build_header(eap, EAP_TYPE_SIM, EAP_SIM_ST_CHALLENGE,
pos, resp_len);
if (sim->protected)
pos += eap_sim_add_attribute(pos, EAP_SIM_AT_RESULT_IND,
EAP_SIM_PAD_NONE, NULL, 2);
/* save MAC position to know where to write it to */
mac_pos = pos;
pos += eap_sim_add_attribute(pos, EAP_SIM_AT_MAC, EAP_SIM_PAD_NONE,
NULL, EAP_SIM_MAC_LEN);
/* append SRES for MAC derivation */
memcpy(pos, sim->sres, EAP_SIM_SRES_LEN * 3);
pos += EAP_SIM_SRES_LEN * 3;
if (!eap_sim_derive_mac(response, pos - response, sim->k_aut,
mac_pos + 4)) {
l_error("could not derive MAC");
goto chal_fatal;
}
eap_send_response(eap, EAP_TYPE_SIM, response, resp_len);
if (!sim->protected) {
/*
* Result indication not required, we must accept success.
*/
eap_method_success(eap);
eap_set_key_material(eap, sim->msk, 32, NULL, 0, NULL, 0);
sim->state = EAP_SIM_STATE_SUCCESS;
}
return;
/*
* fatal, unrecoverable error
*/
chal_fatal:
eap_method_error(eap);
sim->state = EAP_SIM_STATE_ERROR;
return;
chal_error:
eap_sim_client_error(eap, EAP_TYPE_SIM, code);
}
/*
* Handles EAP-SIM Notification subtype
*/
static void handle_notification(struct eap_state *eap, const uint8_t *pkt,
size_t len)
{
struct eap_sim_handle *sim = eap_get_data(eap);
struct eap_sim_tlv_iter iter;
int32_t value = -1;
if (len < 3) {
l_error("packet is too small");
goto notif_error;
}
eap_sim_tlv_iter_init(&iter, pkt + 3, len - 3);
while (eap_sim_tlv_iter_next(&iter)) {
const uint8_t *contents = eap_sim_tlv_iter_get_data(&iter);
uint16_t length = eap_sim_tlv_iter_get_length(&iter);
switch (eap_sim_tlv_iter_get_type(&iter)) {
case EAP_SIM_AT_NOTIFICATION:
if (length < 2) {
l_error("malformed AT_NOTIFICATION");
goto notif_error;
}
value = l_get_be16(contents);
break;
case EAP_SIM_AT_IV:
case EAP_SIM_AT_ENCR_DATA:
case EAP_SIM_AT_PADDING:
case EAP_SIM_AT_MAC:
/* RFC 4186, Section 10.1 */
break;
default:
l_error("attribute type %u not allowed in Notification",
eap_sim_tlv_iter_get_type(&iter));
goto notif_error;
}
}
if (value == EAP_SIM_SUCCESS && sim->protected &&
sim->state == EAP_SIM_STATE_CHALLENGE) {
/* header + MAC + MAC header */
uint8_t response[8 + EAP_SIM_MAC_LEN + 4];
uint8_t *pos = response;
/*
* Server sent successful result indication
*/
eap_method_success(eap);
eap_set_key_material(eap, sim->msk, 32, NULL, 0, NULL, 0);
/*
* Build response packet
*/
pos += eap_sim_build_header(eap, EAP_TYPE_SIM,
EAP_SIM_ST_NOTIFICATION, pos, 20);
pos += eap_sim_add_attribute(pos, EAP_SIM_AT_MAC,
EAP_SIM_PAD_NONE, NULL, EAP_SIM_MAC_LEN);
if (!eap_sim_derive_mac(response, pos - response, sim->k_aut,
response + 12)) {
l_error("could not derive MAC");
eap_method_error(eap);
sim->state = EAP_SIM_STATE_ERROR;
return;
}
eap_send_response(eap, EAP_TYPE_SIM, response, pos - response);
sim->state = EAP_SIM_STATE_SUCCESS;
return;
} else if (value == EAP_SIM_SUCCESS) {
/*
* Unexpected success notification, what should
* be done here?
*/
l_error("Unexpected success notification");
} else {
/*
* All other values are error conditions.
* Nothing unique can be done for any error so
* print the code and signal EAP failure.
*/
l_error("Error authenticating: code=%u", value);
}
notif_error:
eap_sim_client_error(eap, EAP_TYPE_SIM, EAP_SIM_ERROR_PROCESS);
}
static void eap_sim_handle_request(struct eap_state *eap,
const uint8_t *pkt, size_t len)
{
if (len < 1) {
l_error("packet is too small");
goto req_error;
}
switch (pkt[0]) {
case EAP_SIM_ST_START:
handle_start(eap, pkt, len);
break;
case EAP_SIM_ST_CHALLENGE:
handle_challenge(eap, pkt, len);
break;
case EAP_SIM_ST_NOTIFICATION:
handle_notification(eap, pkt, len);
break;
default:
l_error("unknown EAP-SIM subtype: %u", pkt[0]);
goto req_error;
}
return;
req_error:
eap_sim_client_error(eap, EAP_TYPE_SIM, EAP_SIM_ERROR_PROCESS);
}
static bool eap_sim_load_settings(struct eap_state *eap,
struct l_settings *settings,
const char *prefix)
{
struct eap_sim_handle *sim = eap_get_data(eap);
char setting[64];
const char *kcs;
const char *imsi;
const char *sres;
size_t len;
/*
* TODO: These values will be loaded from a SIM card. Kc and SRES
* values should be kept secret and crucial to the security of EAP-SIM.
* It may be better to load them on the fly (from the SIM) as needed
* rather than storing them in the eap_sim_state structure.
*/
snprintf(setting, sizeof(setting), "%sSIM-Kc", prefix);
kcs = l_settings_get_value(settings, "Security", setting);
if (kcs) {
uint8_t *val = l_util_from_hexstring(kcs, &len);
memcpy(sim->kc, val, len);
l_free(val);
}
snprintf(setting, sizeof(setting), "%sSIM-IMSI", prefix);
imsi = l_settings_get_value(settings, "Security", setting);
if (imsi)
sim->identity = l_strdup(imsi);
snprintf(setting, sizeof(setting), "%sSIM-SRES", prefix);
sres = l_settings_get_value(settings, "Security", setting);
if (sres) {
uint8_t *val = l_util_from_hexstring(sres, &len);
memcpy(sim->sres, val, len);
l_free(val);
}
return true;
}
static struct eap_method eap_sim = {
.request_type = EAP_TYPE_SIM,
.exports_msk = true,
.name = "SIM",
.probe = eap_sim_probe,
.remove = eap_sim_remove,
.handle_request = eap_sim_handle_request,
.load_settings = eap_sim_load_settings,
};
static int eap_sim_init(void)
{
l_debug("");
return eap_register_method(&eap_sim);
}
static void eap_sim_exit(void)
{
l_debug("");
eap_unregister_method(&eap_sim);
}
EAP_METHOD_BUILTIN(eap_sim, eap_sim_init, eap_sim_exit)

1
src/eap.h
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@ -71,6 +71,7 @@ enum eap_type {
__EAP_TYPE_MIN_METHOD = 4,
EAP_TYPE_MD5_CHALLENGE = 4,
EAP_TYPE_TLS_EAP = 13,
EAP_TYPE_SIM = 18,
EAP_TYPE_TTLS = 21,
EAP_TYPE_MSCHAPV2 = 26,
EAP_TYPE_EXPANDED = 254,

382
src/simutil.c Normal file
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@ -0,0 +1,382 @@
/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2017 Intel Corporation. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <ctype.h>
#include <stdio.h>
#include <errno.h>
#include <ell/ell.h>
#include "crypto.h"
#include "simutil.h"
/*
* RFC 3174 functions
*/
/*
* Section 3a - Circular left shift function S
*/
#define S(n, x) (((x) << (n)) | ((x) >> (32 - (n))))
/*
* Section 5 - Functions and Constants Used
*
* K(t) - sequence of constant words K(0) - K(79)
* (represented as a function, index t is constant for every 20 indexes)
*/
static uint32_t K(int t)
{
if (t >= 0 && t <= 19)
return 0x5a827999;
else if (t >= 20 && t <= 39)
return 0x6ed9eba1;
else if (t >= 40 && t <= 59)
return 0x8f1bbcdc;
else if (t >= 60 && t <= 79)
return 0xca62c1d6;
return 0;
}
/*
* f(t, B, C, D) - sequence of logical functions f(0) - f(79)
* Every 20 indexes the value of t computes a different bit manipulation of
* B, C and D
*/
static uint32_t f(int t, uint32_t B, uint32_t C, uint32_t D)
{
if (t >= 0 && t <= 19)
return (B & C) | ((~B) & D);
else if (t >= 20 && t <= 39)
return B ^ C ^ D;
else if (t >= 40 && t <= 59)
return (B & C) | (B & D) | (C & D);
else if (t >= 60 && t <= 79)
return B ^ C ^ D;
return 0;
}
/*
* RFC 3174 Section 6.1 Method 1
*
* Core SHA1 block digest function. Computes the SHA1 digest of a single block.
* Named G as it appears in FIPS 182 PRNG.
*
* The Linux kernel does not expose this specific block digest function to the
* user. The SHA1 function exposed in the kernel automatically does the length
* encoded padding to the block which is different than what EAP-SIM requires.
* EAP-SIM requires and extra bits in the block to be zero. This function was
* implemented for this reason.
*/
static void G(uint32_t *out, uint8_t *block)
{
int t;
uint32_t H[5];
uint32_t W[80];
uint32_t A, B, C, D, E;
uint32_t TEMP;
H[0] = out[0];
H[1] = out[1];
H[2] = out[2];
H[3] = out[3];
H[4] = out[4];
/*
* a. Divide M (block) into 16 words, W(0) ... W(15) where W(0) is the
* left-most word
*/
for (t = 0; t < 16; t++) {
/* copy each word */
W[t] = L_BE32_TO_CPU(((uint32_t *)block)[t]);
}
/*
* b. for t = 16 to 79 do
*/
for (t = 16; t <= 79; t++) {
/* W(t) = S^1(W(t-3) XOR W(t-8) XOR W(t-14) XOR W(t-16)) */
W[t] = S(1, (W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]));
}
/* c. Let A = H0, B = H1, C = H2, D = H3, E = H4 */
A = H[0];
B = H[1];
C = H[2];
D = H[3];
E = H[4];
/* d. For t = 0 to 79 do */
for (t = 0; t <= 79; t++) {
/* TEMP = S^5(A) + f(t;B,C,D) + E + W(t) + K(t); */
TEMP = (S(5, A)) + (f(t, B, C, D) + E + W[t] + K(t));
/* E = D; D = C; C = S^30(B); B = A; A = TEMP; */
E = D; D = C; C = S(30, B); B = A; A = TEMP;
}
/*
* e. Let H[0-4] == A, B, C, D, E
*/
H[0] += A;
H[1] += B;
H[2] += C;
H[3] += D;
H[4] += E;
memcpy(out, H, sizeof(H));
}
void eap_sim_fips_prf(const void *seed, size_t slen, uint8_t *out, size_t olen)
{
uint8_t xkey[64];
uint32_t w_i[5];
uint32_t t[] = { 0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476,
0xC3D2E1F0 };
uint8_t *pos = out;
uint32_t c;
int j, i;
/* Copy seed and zero pad remainder */
memcpy(xkey, seed, slen);
memset(xkey + slen, 0, sizeof(xkey) - slen);
for (j = 0; j < (int)olen / 40; j++) {
for (i = 0; i < 2; i++) {
int k;
memcpy(w_i, t, sizeof(t));
/* w_i = G(t, XVAL) */
G(w_i, xkey);
for (k = 0; k < 5; k++)
w_i[k] = L_CPU_TO_BE32(w_i[k]);
memcpy(pos, w_i, 20);
/* XKEY = (1 + XKEY + w_i) mod 2^b*/
c = 1;
for (k = 19; k >= 0; k--) {
uint32_t sum = xkey[k] + pos[k] + c;
xkey[k] = sum & 0xff;
c = sum >> 8;
}
pos += 20;
}
}
}
bool eap_sim_get_encryption_keys(const uint8_t *buf, uint8_t *k_encr,
uint8_t *k_aut, uint8_t *msk, uint8_t *emsk)
{
const uint8_t *pos = buf;
if (!buf || !msk || !emsk) {
l_error("key pointers are invalid");
return false;
}
if (k_encr)
memcpy(k_encr, pos, EAP_SIM_K_ENCR_LEN);
pos += EAP_SIM_K_ENCR_LEN;
if (k_aut)
memcpy(k_aut, pos, EAP_SIM_K_AUT_LEN);
pos += EAP_SIM_K_AUT_LEN;
memcpy(msk, pos, EAP_SIM_MSK_LEN);
pos += EAP_SIM_MSK_LEN;
memcpy(emsk, pos, EAP_SIM_EMSK_LEN);
return true;
}
bool eap_sim_derive_mac(const uint8_t *buf, size_t len, const uint8_t *key,
uint8_t *mac)
{
return hmac_sha1(key, EAP_SIM_K_AUT_LEN, buf, len, mac,
EAP_SIM_MAC_LEN);
}
size_t eap_sim_build_header(struct eap_state *eap, enum eap_type method,
uint8_t type, uint8_t *buf, uint16_t len)
{
buf[0] = 0x02;
eap_save_last_id(eap, &buf[1]);
l_put_be16(len, buf + 2);
buf[4] = method;
buf[5] = type;
buf[6] = 0x00;
buf[7] = 0x00;
return 8;
}
void eap_sim_client_error(struct eap_state *eap, enum eap_type type,
uint16_t code)
{
uint8_t buf[12];
eap_sim_build_header(eap, type, 0x0e, buf, 12);
buf[8] = EAP_SIM_AT_CLIENT_ERROR_CODE;
buf[9] = 1;
l_put_be16(code, buf + 10);
eap_send_response(eap, type, buf, 12);
}
size_t eap_sim_add_attribute(uint8_t *buf, enum eap_sim_at attr,
uint8_t ptype, uint8_t *data, uint16_t dlen)
{
int i;
uint8_t pos = 0;
uint8_t pad = 0;
buf[pos++] = attr;
if (ptype == EAP_SIM_PAD_NONE)
/* no padding indicates data directly follows ID/size */
buf[pos++] = EAP_SIM_ROUND(dlen + 2) / 4;
else
/* any padding indicates 2 extra bytes before data */
buf[pos++] = EAP_SIM_ROUND(dlen + 4) / 4;
if (ptype == EAP_SIM_PAD_LENGTH) {
/* Encode length in next two bytes */
l_put_be16(dlen, buf + pos);
pos += 2;
} else if (ptype == EAP_SIM_PAD_ZERO) {
buf[pos++] = 0x00;
buf[pos++] = 0x00;
} else if (ptype == EAP_SIM_PAD_LENGTH_BITS) {
l_put_be16(dlen * 8, buf + pos);
pos += 2;
} /* else no padding */
if (data)
memcpy(buf + pos, data, dlen);
else
memset(buf + pos, 0, dlen);
pad = (buf[1] * 4) - (dlen + pos);
pos += dlen;
/* If header + data is not in multiple of 4 bytes then pad */
for (i = 0; i < pad; i++)
buf[pos + i] = 0x00;
pos += pad;
return pos;
}
bool eap_sim_verify_mac(struct eap_state *eap, enum eap_type type,
const uint8_t *buf, uint16_t len, uint8_t *k_aut,
uint8_t *extra, size_t elen)
{
struct l_checksum *hmac;
struct eap_sim_tlv_iter iter;
const uint8_t *mac_p = NULL;
uint8_t zero_mac[EAP_SIM_MAC_LEN] = { 0 };
uint8_t hdr[5];
struct iovec iov[4];
eap_sim_tlv_iter_init(&iter, buf + 3, len - 3);
while (eap_sim_tlv_iter_next(&iter)) {
if (eap_sim_tlv_iter_get_type(&iter) == EAP_SIM_AT_MAC) {
mac_p = eap_sim_tlv_iter_get_data(&iter) + 2;
break;
}
}
if (!mac_p) {
l_error("packet did not contain AT_MAC attribute");
return false;
}
/* re-build EAP packet header */
hdr[0] = 0x01;
eap_save_last_id(eap, &hdr[1]);
l_put_be16(len + 5, hdr + 2);
hdr[4] = type;
iov[0].iov_base = (void *)hdr;
iov[0].iov_len = 5;
iov[1].iov_base = (void *)buf;
iov[1].iov_len = len - EAP_SIM_MAC_LEN;
iov[2].iov_base = zero_mac;
iov[2].iov_len = EAP_SIM_MAC_LEN;
iov[3].iov_base = extra;
iov[3].iov_len = elen;
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA1, k_aut, EAP_SIM_K_AUT_LEN);
l_checksum_updatev(hmac, iov, 4);
/* reuse zero mac array for new mac */
l_checksum_get_digest(hmac, zero_mac, EAP_SIM_MAC_LEN);
l_checksum_free(hmac);
if (memcmp(zero_mac, mac_p, EAP_SIM_MAC_LEN)) {
l_error("MAC does not match");
return false;
}
return true;
}
bool eap_sim_tlv_iter_init(struct eap_sim_tlv_iter *iter, const uint8_t *data,
uint32_t len)
{
iter->data = NULL;
iter->pos = data;
iter->len = 0;
iter->end = data + len;
return true;
}
bool eap_sim_tlv_iter_next(struct eap_sim_tlv_iter *iter)
{
/* check room for tag/len */
if (iter->end - iter->pos < 2)
return false;
iter->tag = iter->pos[0];
iter->len = (iter->pos[1] * 4) - 2;
iter->pos += 2;
/* check room for value */
if (iter->end - iter->pos < iter->len)
return false;
iter->data = iter->pos;
iter->pos += iter->len;
return true;
}
uint8_t eap_sim_tlv_iter_get_type(struct eap_sim_tlv_iter *iter)
{
return iter->tag;
}
uint16_t eap_sim_tlv_iter_get_length(struct eap_sim_tlv_iter *iter)
{
return iter->len;
}
const void *eap_sim_tlv_iter_get_data(struct eap_sim_tlv_iter *iter)
{
return iter->data;
}

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/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2017 Intel Corporation. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include "eap.h"
/*
* EAP-SIM/EAP-AKA shared values
*/
#define EAP_SIM_MK_LEN 20
#define EAP_SIM_K_ENCR_LEN 16
#define EAP_SIM_K_AUT_LEN 16
#define EAP_SIM_MSK_LEN 64
#define EAP_SIM_EMSK_LEN 64
#define EAP_SIM_IV_LEN 16
#define EAP_SIM_MAC_LEN 16
#define EAP_SIM_RAND_LEN 16
/*
* Possible pad types for EAP-SIM/EAP-AKA attributes
*
* NONE - No padding, data passed in immediately follows type/size
* ZERO - Zero pad where "real" length would be
* LENGTH - A "real" data length in bytes immediately follows type/size
* LENGTH_BITS - A "real" data length in bits follows type/size
*/
#define EAP_SIM_PAD_NONE 0
#define EAP_SIM_PAD_ZERO 1
#define EAP_SIM_PAD_LENGTH 2
#define EAP_SIM_PAD_LENGTH_BITS 3
/*
* Round up value to nearest word
*/
#define EAP_SIM_ROUND(x) ((x + 3) & ~0x3)
struct eap_sim_tlv_iter {
const uint8_t *pos;
const uint8_t *end;
uint8_t tag;
uint16_t len;
const uint8_t *data;
};
/*
* RFC 4187, section 11
*/
enum eap_sim_at {
EAP_SIM_AT_RAND = 0x01,
EAP_SIM_AT_AUTN = 0x02,
EAP_SIM_AT_RES = 0x03,
EAP_SIM_AT_AUTS = 0x04,
EAP_SIM_AT_PADDING = 0x06,
EAP_SIM_AT_NONCE = 0x07,
EAP_SIM_AT_PERMANENT_ID_REQ = 0x0a,
EAP_SIM_AT_MAC = 0x0b,
EAP_SIM_AT_NOTIFICATION = 0x0c,
EAP_SIM_AT_ANY_ID_REQ = 0x0d,
EAP_SIM_AT_IDENTITY = 0x0e,
EAP_SIM_AT_VERSION_LIST = 0x0f,
EAP_SIM_AT_SELECTED_VERSION = 0x10,
EAP_SIM_AT_FULLAUTH_ID_REQ = 0x11,
EAP_SIM_AT_COUNTER = 0x13,
EAP_SIM_AT_NONCE_S = 0x15,
EAP_SIM_AT_CLIENT_ERROR_CODE = 0x16,
EAP_SIM_AT_KDF_INPUT = 0x17,
EAP_SIM_AT_IV = 0x81,
EAP_SIM_AT_ENCR_DATA = 0x82,
EAP_SIM_AT_NEXT_PSEUDONYM = 0x84,
EAP_SIM_AT_NEXT_REAUTH_ID = 0x85,
EAP_SIM_AT_CHECKCODE = 0x86,
EAP_SIM_AT_RESULT_IND = 0x87,
EAP_SIM_AT_BIDDING = 0x88
};
/*
* Possible client error's
*/
enum eap_sim_error {
EAP_SIM_ERROR_PROCESS = 0,
EAP_SIM_ERROR_VERSION_VERSION,
EAP_SIM_ERROR_CHALLENGE,
EAP_SIM_ERROR_RANDS
};
/*
* Notification error codes (and success).
*/
enum eap_sim_fail {
EAP_SIM_FAIL_AFTER_AUTH = 0,
EAP_SIM_FAIL_DENIED_ACCESS = 1026,
EAP_SIM_FAIL_NOT_SUBSCRIBED = 1031,
EAP_SIM_FAIL_BEFORE_AUTH = 16384,
EAP_SIM_SUCCESS = 32768
};
/*
* RFC 4186 Appendix B. FIPS 186 Pseudo-random number generator
*
* seed - PRF seed, e.g. the Master Key (MK)
* slen - seed length
* out - PRF output buffer
* olen - length of out
*/
void eap_sim_fips_prf(const void *seed, size_t slen, uint8_t *out, size_t olen);
/*
* Separate PRNG data into encryption keys. k_encr and k_aut may be NULL in the
* case of fast re-authentication.
*
* buf - output data from the PRNG, 160 bytes
* k_encr - first 16 bytes of buf
* k_aut - next 16 bytes of buf
* msk - next 64 bytes of buf
* emsk - next 64 bytes of buf
*/
bool eap_sim_get_encryption_keys(const uint8_t *buf, uint8_t *k_encr,
uint8_t *k_aut, uint8_t *msk, uint8_t *emsk);
/*
* Derive a packets MAC. This can be used to compute the packets MAC in place,
* by setting mac to the proper zero'ed location in buf.
*
* buf - the SIM packet, including MAC portion zero'ed, plus extra (e.g. SRES)
* len - the total length of buf
* key - encryption key to use (e.g. K_encr)
* mac - buffer for the 16 byte MAC
*/
bool eap_sim_derive_mac(const uint8_t *buf, size_t len, const uint8_t *key,
uint8_t *mac);
/*
* Helper to build the EAP packet header
*
* eap - eap_state, used to get the identifier
* method - EAP method (SIM or AKA)
* type - EAP-SIM subtype
* buf - EAP packet
* len - length of packet
*/
size_t eap_sim_build_header(struct eap_state *eap, enum eap_type method,
uint8_t type, uint8_t *buf, uint16_t len);
/*
* Signal that the client has detected an error
*
* eap - eap_state
* type - type of EAP method (SIM or AKA)
* code - error code to send
*/
void eap_sim_client_error(struct eap_state *eap, enum eap_type type,
uint16_t code);
/*
* Add an EAP-SIM attribute to a buffer.
*
* buf - pointer to start of EAP-SIM attribute
* attr - type of attribute
* ptype - Padding type AT_PAD_ZERO, AT_PAD_NONE or AT_PAD_LENGTH
* data - EAP-SIM attribute data, if NULL zeros will be written
* dlen - length of data pointer in bytes
*
* Returns the number of bytes written to buf.
*/
size_t eap_sim_add_attribute(uint8_t *buf, enum eap_sim_at attr,
uint8_t ptype, uint8_t *data, uint16_t dlen);
/*
* Verify a packets MAC
*
* eap - eap_state pointer, used to rebuild the EAP header
* buf - should point to the start of the EAP-SIM packet
* len - length of EAP packet
* extra - Any extra block of data needed to compute the MAC
* elen - Length of 'extra'
*/
bool eap_sim_verify_mac(struct eap_state *eap, enum eap_type type,
const uint8_t *buf, uint16_t len, uint8_t *k_aut,
uint8_t *extra, size_t elen);
bool eap_sim_tlv_iter_init(struct eap_sim_tlv_iter *iter, const uint8_t *data,
uint32_t len);
bool eap_sim_tlv_iter_next(struct eap_sim_tlv_iter *iter);
uint8_t eap_sim_tlv_iter_get_type(struct eap_sim_tlv_iter *iter);
uint16_t eap_sim_tlv_iter_get_length(struct eap_sim_tlv_iter *iter);
const void *eap_sim_tlv_iter_get_data(struct eap_sim_tlv_iter *iter);