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mirror of https://git.kernel.org/pub/scm/network/wireless/iwd.git synced 2024-11-07 20:49:22 +01:00
iwd/src/simutil.c
Andrew Zaborowski c826dd0052 eap: Simplify sending EAP method responses
Replace the usage of eap_send_response() in the method implementations
with a new eap_method_respond that skips the redundant "type" parameter.
The new eap_send_packet is used inside eap_method_respond and will be
reused for sending request packets in authenticator side EAP methods.
2020-08-13 10:36:43 -05:00

506 lines
12 KiB
C

/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2017-2019 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 "src/missing.h"
#include "src/eap-private.h"
#include "src/crypto.h"
#include "src/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));
}
bool eap_aka_derive_primes(const uint8_t *ck, const uint8_t *ik,
const uint8_t *autn, const uint8_t *network, uint16_t net_len,
uint8_t *ck_p, uint8_t *ik_p)
{
struct iovec iov[5];
struct l_checksum *hmac;
uint8_t key[32];
uint8_t fc = 0x20;
uint16_t l1 = L_CPU_TO_BE16(6);
uint16_t name_len = L_CPU_TO_BE16(net_len);
uint8_t digest[32];
memcpy(key, ck, EAP_AKA_CK_LEN);
memcpy(key + EAP_AKA_CK_LEN, ik, EAP_AKA_IK_LEN);
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, key, 32);
explicit_bzero(key, sizeof(key));
if (!hmac)
return false;
iov[0].iov_base = &fc;
iov[0].iov_len = 1;
iov[1].iov_base = (void *)network;
iov[1].iov_len = net_len;
iov[2].iov_base = &name_len;
iov[2].iov_len = 2;
iov[3].iov_base = (void *)autn;
iov[3].iov_len = 6;
iov[4].iov_base = &l1;
iov[4].iov_len = 2;
l_checksum_updatev(hmac, iov, 5);
l_checksum_get_digest(hmac, digest, 32);
l_checksum_free(hmac);
memcpy(ck_p, digest, EAP_AKA_CK_LEN);
memcpy(ik_p, digest + EAP_AKA_CK_LEN, EAP_AKA_IK_LEN);
explicit_bzero(digest, sizeof(digest));
return true;
}
bool eap_aka_prf_prime(const uint8_t *ik_p, const uint8_t *ck_p,
const char *identity, uint8_t *k_encr, uint8_t *k_aut,
uint8_t *k_re, uint8_t *msk, uint8_t *emsk)
{
struct l_checksum *hmac;
uint8_t key[32];
struct iovec iov[4];
/* digest continues to be reused each iteration */
uint8_t digest[32];
uint8_t i = 0x01;
/* 7 iterations will be 224 bytes, 208 of which will get used */
uint8_t out[224];
uint8_t *pos = out;
/* K = (IK'|CK') */
memcpy(key, ik_p, EAP_AKA_IK_LEN);
memcpy(key + EAP_AKA_IK_LEN, ck_p, EAP_AKA_CK_LEN);
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, key, 32);
explicit_bzero(key, sizeof(key));
if (!hmac)
return false;
iov[0].iov_base = digest;
/* initial iteration digest is not used */
iov[0].iov_len = 0;
iov[1].iov_base = (void *)"EAP-AKA'";
iov[1].iov_len = strlen("EAP-AKA'");
iov[2].iov_base = (void *)identity;
iov[2].iov_len = strlen(identity);
iov[3].iov_base = &i;
iov[3].iov_len = 1;
/* need 208 bytes for all keys */
while (pos < out + 224) {
l_checksum_reset(hmac);
l_checksum_updatev(hmac, iov, 4);
l_checksum_get_digest(hmac, digest, 32);
memcpy(pos, digest, 32);
pos += 32;
i++;
/* set the digest length so it can be prepended as Tn */
iov[0].iov_len = 32;
}
explicit_bzero(digest, sizeof(digest));
l_checksum_free(hmac);
pos = out;
memcpy(k_encr, pos, EAP_SIM_K_ENCR_LEN);
pos += EAP_SIM_K_ENCR_LEN;
memcpy(k_aut, pos, EAP_AKA_PRIME_K_AUT_LEN);
pos += EAP_AKA_PRIME_K_AUT_LEN;
memcpy(k_re, pos, EAP_AKA_K_RE_LEN);
pos += EAP_AKA_K_RE_LEN;
memcpy(msk, pos, EAP_SIM_MSK_LEN);
pos += EAP_SIM_MSK_LEN;
memcpy(emsk, pos, EAP_SIM_EMSK_LEN);
explicit_bzero(out, sizeof(out));
return true;
}
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(enum eap_type type, const uint8_t *buf, size_t len,
const uint8_t *key, uint8_t *mac)
{
if (type == EAP_TYPE_AKA_PRIME)
return hmac_sha256(key, EAP_AKA_PRIME_K_AUT_LEN, buf, len,
mac, EAP_SIM_MAC_LEN);
else
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_method_respond(eap, buf, 12);
}
size_t eap_sim_add_attribute(uint8_t *buf, enum eap_sim_at attr,
uint8_t ptype, const 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;
if (type == EAP_TYPE_AKA_PRIME)
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, k_aut,
EAP_AKA_PRIME_K_AUT_LEN);
else
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;
}