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SAE-PK: Extend SAE functionality for AP validation

Browse Source 
This adds core SAE functionality for a new mode of using SAE with a
specially constructed password that contains a fingerprint for an AP
public key and that public key being used to validate an additional
signature in SAE confirm from the AP.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2020-05-30 23:30:42 +03:00 committed by Jouni Malinen
parent b6dcbd01a6
commit 6b9e99e571
9 changed files with 801 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
hostapd/Android.mk
View File

@ -250,6 +250,10 @@ endif
ifdef CONFIG_SAE
L_CFLAGS += -DCONFIG_SAE
OBJS += src/common/sae.c
ifdef CONFIG_SAE_PK
L_CFLAGS += -DCONFIG_SAE_PK
OBJS += src/common/sae_pk.c
endif
NEED_ECC=y
NEED_DH_GROUPS=y
NEED_HMAC_SHA256_KDF=y

4
hostapd/Makefile
View File

@ -294,6 +294,10 @@ endif
ifdef CONFIG_SAE
CFLAGS += -DCONFIG_SAE
OBJS += ../src/common/sae.o
ifdef CONFIG_SAE_PK
CFLAGS += -DCONFIG_SAE_PK
OBJS += ../src/common/sae_pk.o
endif
NEED_ECC=y
NEED_DH_GROUPS=y
NEED_HMAC_SHA256_KDF=y

2
src/ap/ieee802_11.c
View File

@ -515,7 +515,7 @@ static struct wpabuf * auth_build_sae_commit(struct hostapd_data *hapd,
if (update && use_pt &&
sae_prepare_commit_pt(sta->sae, pt, hapd->own_addr, sta->addr,
NULL) < 0)
NULL, NULL) < 0)
return NULL;
if (update && !use_pt &&

75
src/common/sae.c
View File

@ -112,6 +112,9 @@ void sae_clear_temp_data(struct sae_data *sae)
wpabuf_free(tmp->own_rejected_groups);
wpabuf_free(tmp->peer_rejected_groups);
os_free(tmp->pw_id);
#ifdef CONFIG_SAE_PK
bin_clear_free(tmp->pw, tmp->pw_len);
#endif /* CONFIG_SAE_PK */
bin_clear_free(tmp, sizeof(*tmp));
sae->tmp = NULL;
}
@ -1052,10 +1055,17 @@ sae_derive_pt_group(int group, const u8 *ssid, size_t ssid_len,
wpa_printf(MSG_DEBUG, "SAE: Derive PT - group %d", group);
if (ssid_len > 32)
return NULL;
pt = os_zalloc(sizeof(*pt));
if (!pt)
return NULL;
#ifdef CONFIG_SAE_PK
os_memcpy(pt->ssid, ssid, ssid_len);
pt->ssid_len = ssid_len;
#endif /* CONFIG_SAE_PK */
pt->group = group;
pt->ec = crypto_ec_init(group);
if (pt->ec) {
@ -1355,13 +1365,14 @@ int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
return -1;
sae->tmp->h2e = 0;
sae->tmp->pk = 0;
return sae_derive_commit(sae);
}
int sae_prepare_commit_pt(struct sae_data *sae, const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2,
int *rejected_groups)
int *rejected_groups, const struct sae_pk *pk)
{
if (!sae->tmp)
return -1;
@ -1377,6 +1388,20 @@ int sae_prepare_commit_pt(struct sae_data *sae, const struct sae_pt *pt,
return -1;
}
#ifdef CONFIG_SAE_PK
os_memcpy(sae->tmp->ssid, pt->ssid, pt->ssid_len);
sae->tmp->ssid_len = pt->ssid_len;
sae->tmp->ap_pk = pk;
/* TODO: Could support alternative groups as long as the combination
* meets the requirements. */
if (pk && pk->group != sae->group) {
wpa_printf(MSG_DEBUG,
"SAE-PK: Reject attempt to use group %d since K_AP use group %d",
sae->group, pk->group);
sae->tmp->reject_group = true;
return -1;
}
#endif /* CONFIG_SAE_PK */
sae->tmp->own_addr_higher = os_memcmp(addr1, addr2, ETH_ALEN) > 0;
wpabuf_free(sae->tmp->own_rejected_groups);
sae->tmp->own_rejected_groups = NULL;
@ -1515,7 +1540,7 @@ static int sae_derive_keys(struct sae_data *sae, const u8 *k)
const u8 *salt;
struct wpabuf *rejected_groups = NULL;
u8 keyseed[SAE_MAX_HASH_LEN];
u8 keys[SAE_MAX_HASH_LEN + SAE_PMK_LEN];
u8 keys[2 * SAE_MAX_HASH_LEN + SAE_PMK_LEN];
struct crypto_bignum *tmp;
int ret = -1;
size_t hash_len, salt_len, prime_len = sae->tmp->prime_len;
@ -1530,6 +1555,9 @@ static int sae_derive_keys(struct sae_data *sae, const u8 *k)
* KCK || PMK = KDF-Hash-Length(keyseed, "SAE KCK and PMK",
* (commit-scalar + peer-commit-scalar) modulo r)
* PMKID = L((commit-scalar + peer-commit-scalar) modulo r, 0, 128)
*
* When SAE-PK is used,
* KCK || PMK || KEK = KDF-Hash-Length(keyseed, "SAE-PK keys", context)
*/
if (!sae->tmp->h2e)
hash_len = SHA256_MAC_LEN;
@ -1589,15 +1617,32 @@ static int sae_derive_keys(struct sae_data *sae, const u8 *k)
* octets). */
crypto_bignum_to_bin(tmp, val, sizeof(val), sae->tmp->order_len);
wpa_hexdump(MSG_DEBUG, "SAE: PMKID", val, SAE_PMKID_LEN);
if (sae_kdf_hash(hash_len, keyseed, "SAE KCK and PMK",
if (!sae->tmp->pk &&
sae_kdf_hash(hash_len, keyseed, "SAE KCK and PMK",
val, sae->tmp->order_len,
keys, hash_len + SAE_PMK_LEN) < 0)
goto fail;
#ifdef CONFIG_SAE_PK
if (sae->tmp->pk &&
sae_kdf_hash(hash_len, keyseed, "SAE-PK keys",
val, sae->tmp->order_len,
keys, 2 * hash_len + SAE_PMK_LEN) < 0)
goto fail;
#endif /* CONFIG_SAE_PK */
forced_memzero(keyseed, sizeof(keyseed));
os_memcpy(sae->tmp->kck, keys, hash_len);
sae->tmp->kck_len = hash_len;
os_memcpy(sae->pmk, keys + hash_len, SAE_PMK_LEN);
os_memcpy(sae->pmkid, val, SAE_PMKID_LEN);
#ifdef CONFIG_SAE_PK
if (sae->tmp->pk) {
os_memcpy(sae->tmp->kek, keys + hash_len + SAE_PMK_LEN,
hash_len);
sae->tmp->kek_len = hash_len;
wpa_hexdump_key(MSG_DEBUG, "SAE: KEK for SAE-PK",
sae->tmp->kek, sae->tmp->kek_len);
}
#endif /* CONFIG_SAE_PK */
forced_memzero(keys, sizeof(keys));
wpa_hexdump_key(MSG_DEBUG, "SAE: KCK",
sae->tmp->kck, sae->tmp->kck_len);
@ -2189,13 +2234,14 @@ static int sae_cn_confirm_ffc(struct sae_data *sae, const u8 *sc,
}
void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf)
int sae_write_confirm(struct sae_data *sae, struct wpabuf *buf)
{
const u8 *sc;
size_t hash_len;
int res;
if (sae->tmp == NULL)
return;
return -1;
hash_len = sae->tmp->kck_len;
@ -2206,17 +2252,26 @@ void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf)
sae->send_confirm++;
if (sae->tmp->ec)
sae_cn_confirm_ecc(sae, sc, sae->tmp->own_commit_scalar,
res = sae_cn_confirm_ecc(sae, sc, sae->tmp->own_commit_scalar,
sae->tmp->own_commit_element_ecc,
sae->peer_commit_scalar,
sae->tmp->peer_commit_element_ecc,
wpabuf_put(buf, hash_len));
else
sae_cn_confirm_ffc(sae, sc, sae->tmp->own_commit_scalar,
res = sae_cn_confirm_ffc(sae, sc, sae->tmp->own_commit_scalar,
sae->tmp->own_commit_element_ffc,
sae->peer_commit_scalar,
sae->tmp->peer_commit_element_ffc,
wpabuf_put(buf, hash_len));
if (res)
return res;
#ifdef CONFIG_SAE_PK
if (sae_write_confirm_pk(sae, buf) < 0)
return -1;
#endif /* CONFIG_SAE_PK */
return 0;
}
@ -2270,6 +2325,12 @@ int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len)
return -1;
}
#ifdef CONFIG_SAE_PK
if (sae_check_confirm_pk(sae, data + 2 + hash_len,
len - 2 - hash_len) < 0)
return -1;
#endif /* CONFIG_SAE_PK */
return 0;
}

56
src/common/sae.h
View File

@ -16,11 +16,24 @@
#define SAE_MAX_ECC_PRIME_LEN 66
#define SAE_MAX_HASH_LEN 64
#define SAE_COMMIT_MAX_LEN (2 + 3 * SAE_MAX_PRIME_LEN + 255)
#ifdef CONFIG_SAE_PK
#define SAE_CONFIRM_MAX_LEN ((2 + SAE_MAX_HASH_LEN) + 1500)
#else /* CONFIG_SAE_PK */
#define SAE_CONFIRM_MAX_LEN (2 + SAE_MAX_HASH_LEN)
#endif /* CONFIG_SAE_PK */
#define SAE_PK_M_LEN 16
/* Special value returned by sae_parse_commit() */
#define SAE_SILENTLY_DISCARD 65535
struct sae_pk {
struct wpabuf *m;
struct crypto_ec_key *key;
int group;
struct wpabuf *pubkey; /* DER encoded subjectPublicKey */
};
struct sae_temporary_data {
u8 kck[SAE_MAX_HASH_LEN];
size_t kck_len;
@ -47,7 +60,22 @@ struct sae_temporary_data {
struct wpabuf *own_rejected_groups;
struct wpabuf *peer_rejected_groups;
unsigned int h2e:1;
unsigned int pk:1;
unsigned int own_addr_higher:1;
#ifdef CONFIG_SAE_PK
u8 kek[SAE_MAX_HASH_LEN];
size_t kek_len;
const struct sae_pk *ap_pk;
u8 own_addr[ETH_ALEN];
u8 peer_addr[ETH_ALEN];
u8 *pw;
size_t pw_len;
size_t lambda;
u8 ssid[32];
size_t ssid_len;
bool reject_group;
#endif /* CONFIG_SAE_PK */
};
struct sae_pt {
@ -58,6 +86,10 @@ struct sae_pt {
const struct dh_group *dh;
struct crypto_bignum *ffc_pt;
#ifdef CONFIG_SAE_PK
u8 ssid[32];
size_t ssid_len;
#endif /* CONFIG_SAE_PK */
};
enum sae_state {
@ -86,17 +118,19 @@ int sae_prepare_commit(const u8 *addr1, const u8 *addr2,
const char *identifier, struct sae_data *sae);
int sae_prepare_commit_pt(struct sae_data *sae, const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2,
int *rejected_groups);
int *rejected_groups, const struct sae_pk *pk);
int sae_process_commit(struct sae_data *sae);
int sae_write_commit(struct sae_data *sae, struct wpabuf *buf,
const struct wpabuf *token, const char *identifier);
u16 sae_parse_commit(struct sae_data *sae, const u8 *data, size_t len,
const u8 **token, size_t *token_len, int *allowed_groups,
int h2e);
void sae_write_confirm(struct sae_data *sae, struct wpabuf *buf);
int sae_write_confirm(struct sae_data *sae, struct wpabuf *buf);
int sae_check_confirm(struct sae_data *sae, const u8 *data, size_t len);
u16 sae_group_allowed(struct sae_data *sae, int *allowed_groups, u16 group);
const char * sae_state_txt(enum sae_state state);
size_t sae_ecc_prime_len_2_hash_len(size_t prime_len);
size_t sae_ffc_prime_len_2_hash_len(size_t prime_len);
struct sae_pt * sae_derive_pt(int *groups, const u8 *ssid, size_t ssid_len,
const u8 *password, size_t password_len,
const char *identifier);
@ -108,4 +142,22 @@ sae_derive_pwe_from_pt_ffc(const struct sae_pt *pt,
const u8 *addr1, const u8 *addr2);
void sae_deinit_pt(struct sae_pt *pt);
/* sae_pk.c */
#ifdef CONFIG_SAE_PK
bool sae_pk_valid_password(const char *pw);
#else /* CONFIG_SAE_PK */
static inline bool sae_pk_valid_password(const char *pw)
{
return false;
}
#endif /* CONFIG_SAE_PK */
char * sae_pk_base32_encode(const u8 *src, size_t len_bits);
u8 * sae_pk_base32_decode(const char *src, size_t len, size_t *out_len);
int sae_pk_set_password(struct sae_data *sae, const char *password);
void sae_deinit_pk(struct sae_pk *pk);
struct sae_pk * sae_parse_pk(const char *val);
int sae_write_confirm_pk(struct sae_data *sae, struct wpabuf *buf);
int sae_check_confirm_pk(struct sae_data *sae, const u8 *ies, size_t ies_len);
int sae_hash(size_t hash_len, const u8 *data, size_t len, u8 *hash);
#endif /* SAE_H */

653
src/common/sae_pk.c Normal file
View File

@ -0,0 +1,653 @@
/*
* SAE-PK
* Copyright (c) 2020, The Linux Foundation
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "utils/includes.h"
#include <stdint.h>
#include "utils/common.h"
#include "utils/base64.h"
#include "common/ieee802_11_defs.h"
#include "common/ieee802_11_common.h"
#include "crypto/crypto.h"
#include "crypto/aes.h"
#include "crypto/aes_siv.h"
#include "sae.h"
/* RFC 4648 base 32 alphabet with lowercase characters */
static const char *sae_pk_base32_table = "abcdefghijklmnopqrstuvwxyz234567";
bool sae_pk_valid_password(const char *pw)
{
int pos;
/* Minimum password length for SAE-PK is not defined, but the automatic
* password style determination is more reliable if at least one hyphen
* is forced to be present in the password. */
if (os_strlen(pw) < 6)
return false;
for (pos = 0; pw[pos]; pos++) {
if (pos && pos % 5 == 4) {
if (pw[pos] != '-')
return false;
continue;
}
if (!os_strchr(sae_pk_base32_table, pw[pos]))
return false;
}
if (pos == 0)
return false;
return pw[pos - 1] != '-';
}
static char * add_char(const char *start, char *pos, u8 idx, size_t *bits)
{
if (*bits == 0)
return pos;
if (*bits > 5)
*bits -= 5;
else
*bits = 0;
if ((pos - start) % 5 == 4)
*pos++ = '-';
*pos++ = sae_pk_base32_table[idx];
return pos;
}
char * sae_pk_base32_encode(const u8 *src, size_t len_bits)
{
char *out, *pos;
size_t olen, extra_pad, i;
u64 block = 0;
u8 val;
size_t len = (len_bits + 7) / 8;
size_t left = len_bits;
int j;
if (len == 0 || len >= SIZE_MAX / 8)
return NULL;
olen = len * 8 / 5 + 1;
olen += olen / 4; /* hyphen separators */
pos = out = os_zalloc(olen + 1);
if (!out)
return NULL;
extra_pad = (5 - len % 5) % 5;
for (i = 0; i < len + extra_pad; i++) {
val = i < len ? src[i] : 0;
block <<= 8;
block |= val;
if (i % 5 == 4) {
for (j = 7; j >= 0; j--)
pos = add_char(out, pos,
(block >> j * 5) & 0x1f, &left);
block = 0;
}
}
return out;
}
u8 * sae_pk_base32_decode(const char *src, size_t len, size_t *out_len)
{
u8 dtable[256], *out, *pos, tmp;
u64 block = 0;
size_t i, count, olen;
int pad = 0;
size_t extra_pad;
os_memset(dtable, 0x80, 256);
for (i = 0; sae_pk_base32_table[i]; i++)
dtable[(u8) sae_pk_base32_table[i]] = i;
dtable['='] = 0;
count = 0;
for (i = 0; i < len; i++) {
if (dtable[(u8) src[i]] != 0x80)
count++;
}
if (count == 0)
return NULL;
extra_pad = (8 - count % 8) % 8;
olen = (count + extra_pad) / 8 * 5;
pos = out = os_malloc(olen);
if (!out)
return NULL;
count = 0;
for (i = 0; i < len + extra_pad; i++) {
u8 val;
if (i >= len)
val = '=';
else
val = src[i];
tmp = dtable[val];
if (tmp == 0x80)
continue;
if (val == '=')
pad++;
block <<= 5;
block |= tmp;
count++;
if (count == 8) {
*pos++ = (block >> 32) & 0xff;
*pos++ = (block >> 24) & 0xff;
*pos++ = (block >> 16) & 0xff;
*pos++ = (block >> 8) & 0xff;
*pos++ = block & 0xff;
count = 0;
block = 0;
if (pad) {
/* Leave in all the available bits with zero
* padding to full octets from right. */
pos -= pad * 5 / 8;
break;
}
}
}
*out_len = pos - out;
return out;
}
int sae_pk_set_password(struct sae_data *sae, const char *password)
{
struct sae_temporary_data *tmp = sae->tmp;
size_t len;
len = os_strlen(password);
if (!tmp || len < 1)
return -1;
bin_clear_free(tmp->pw, tmp->pw_len);
tmp->pw = sae_pk_base32_decode(password, len, &tmp->pw_len);
tmp->lambda = len - len / 5;
return tmp->pw ? 0 : -1;
}
void sae_deinit_pk(struct sae_pk *pk)
{
if (pk) {
wpabuf_free(pk->m);
crypto_ec_key_deinit(pk->key);
wpabuf_free(pk->pubkey);
os_free(pk);
}
}
struct sae_pk * sae_parse_pk(const char *val)
{
struct sae_pk *pk;
const char *pos;
size_t len;
unsigned char *der;
size_t der_len;
/* <m-as-hexdump>:<base64-encoded-DER-encoded-key> */
pos = os_strchr(val, ':');
if (!pos || (pos - val) & 0x01)
return NULL;
len = (pos - val) / 2;
if (len != SAE_PK_M_LEN) {
wpa_printf(MSG_INFO, "SAE: Unexpected Modifier M length %zu",
len);
return NULL;
}
pk = os_zalloc(sizeof(*pk));
if (!pk)
return NULL;
pk->m = wpabuf_alloc(len);
if (!pk->m || hexstr2bin(val, wpabuf_put(pk->m, len), len)) {
wpa_printf(MSG_INFO, "SAE: Failed to parse m");
goto fail;
}
pos++;
der = base64_decode(pos, os_strlen(pos), &der_len);
if (!der) {
wpa_printf(MSG_INFO, "SAE: Failed to base64 decode PK key");
goto fail;
}
pk->key = crypto_ec_key_parse_priv(der, der_len);
bin_clear_free(der, der_len);
if (!pk->key)
goto fail;
pk->group = crypto_ec_key_group(pk->key);
pk->pubkey = crypto_ec_key_get_subject_public_key(pk->key);
if (!pk->pubkey)
goto fail;
return pk;
fail:
sae_deinit_pk(pk);
return NULL;
}
int sae_hash(size_t hash_len, const u8 *data, size_t len, u8 *hash)
{
if (hash_len == 32)
return sha256_vector(1, &data, &len, hash);
#ifdef CONFIG_SHA384
if (hash_len == 48)
return sha384_vector(1, &data, &len, hash);
#endif /* CONFIG_SHA384 */
#ifdef CONFIG_SHA512
if (hash_len == 64)
return sha512_vector(1, &data, &len, hash);
#endif /* CONFIG_SHA512 */
return -1;
}
static int sae_pk_hash_sig_data(struct sae_data *sae, size_t hash_len,
bool ap, const u8 *m, size_t m_len,
const u8 *pubkey, size_t pubkey_len, u8 *hash)
{
struct sae_temporary_data *tmp = sae->tmp;
struct wpabuf *sig_data;
u8 *pos;
int ret = -1;
/* Signed data for KeyAuth: eleAP || eleSTA || scaAP || scaSTA ||
* M || K_AP || AP-BSSID || STA-MAC */
sig_data = wpabuf_alloc(tmp->prime_len * 6 + m_len + pubkey_len +
2 * ETH_ALEN);
if (!sig_data)
goto fail;
pos = wpabuf_put(sig_data, 2 * tmp->prime_len);
if (crypto_ec_point_to_bin(tmp->ec, ap ? tmp->own_commit_element_ecc :
tmp->peer_commit_element_ecc,
pos, pos + tmp->prime_len) < 0)
goto fail;
pos = wpabuf_put(sig_data, 2 * tmp->prime_len);
if (crypto_ec_point_to_bin(tmp->ec, ap ? tmp->peer_commit_element_ecc :
tmp->own_commit_element_ecc,
pos, pos + tmp->prime_len) < 0)
goto fail;
if (crypto_bignum_to_bin(ap ? tmp->own_commit_scalar :
sae->peer_commit_scalar,
wpabuf_put(sig_data, tmp->prime_len),
tmp->prime_len, tmp->prime_len) < 0 ||
crypto_bignum_to_bin(ap ? sae->peer_commit_scalar :
tmp->own_commit_scalar,
wpabuf_put(sig_data, tmp->prime_len),
tmp->prime_len, tmp->prime_len) < 0)
goto fail;
wpabuf_put_data(sig_data, m, m_len);
wpabuf_put_data(sig_data, pubkey, pubkey_len);
wpabuf_put_data(sig_data, ap ? tmp->own_addr : tmp->peer_addr,
ETH_ALEN);
wpabuf_put_data(sig_data, ap ? tmp->peer_addr : tmp->own_addr,
ETH_ALEN);
wpa_hexdump_buf_key(MSG_DEBUG, "SAE-PK: Data to be signed for KeyAuth",
sig_data);
if (sae_hash(hash_len, wpabuf_head(sig_data), wpabuf_len(sig_data),
hash) < 0)
goto fail;
wpa_hexdump(MSG_DEBUG, "SAE-PK: hash(data to be signed)",
hash, hash_len);
ret = 0;
fail:
wpabuf_free(sig_data);
return ret;
}
int sae_write_confirm_pk(struct sae_data *sae, struct wpabuf *buf)
{
struct sae_temporary_data *tmp = sae->tmp;
struct wpabuf *elem = NULL, *sig = NULL;
size_t extra;
int ret = -1;
u8 *encr_mod;
size_t encr_mod_len;
const struct sae_pk *pk;
u8 hash[SAE_MAX_HASH_LEN];
size_t hash_len;
if (!tmp)
return -1;
pk = tmp->ap_pk;
if (!pk)
return 0;
if (tmp->kek_len != 32 && tmp->kek_len != 48 && tmp->kek_len != 64) {
wpa_printf(MSG_INFO, "SAE-PK: No KEK available for confirm");
return -1;
}
if (!tmp->ec) {
/* Only ECC groups are supported for SAE-PK in the current
* implementation. */
wpa_printf(MSG_INFO,
"SAE-PK: SAE commit did not use an ECC group");
return -1;
}
hash_len = sae_ecc_prime_len_2_hash_len(tmp->prime_len);
if (sae_pk_hash_sig_data(sae, hash_len, true, wpabuf_head(pk->m),
wpabuf_len(pk->m), wpabuf_head(pk->pubkey),
wpabuf_len(pk->pubkey), hash) < 0)
goto fail;
sig = crypto_ec_key_sign(pk->key, hash, hash_len);
if (!sig)
goto fail;
wpa_hexdump_buf(MSG_DEBUG, "SAE-PK: KeyAuth = Sig_AP()", sig);
elem = wpabuf_alloc(1500 + wpabuf_len(sig));
if (!elem)
goto fail;
/* EncryptedModifier = AES-SIV-Q(M); no AAD */
encr_mod_len = wpabuf_len(pk->m) + AES_BLOCK_SIZE;
wpabuf_put_u8(elem, encr_mod_len);
encr_mod = wpabuf_put(elem, encr_mod_len);
if (aes_siv_encrypt(tmp->kek, tmp->kek_len,
wpabuf_head(pk->m), wpabuf_len(pk->m),
0, NULL, NULL, encr_mod) < 0)
goto fail;
wpa_hexdump(MSG_DEBUG, "SAE-PK: EncryptedModifier",
encr_mod, encr_mod_len);
/* FILS Public Key element */
wpabuf_put_u8(elem, WLAN_EID_EXTENSION);
wpabuf_put_u8(elem, 2 + wpabuf_len(pk->pubkey));
wpabuf_put_u8(elem, WLAN_EID_EXT_FILS_PUBLIC_KEY);
wpabuf_put_u8(elem, 3); /* Key Type: ECDSA public key */
wpabuf_put_buf(elem, pk->pubkey);
/* FILS Key Confirmation element (KeyAuth) */
wpabuf_put_u8(elem, WLAN_EID_EXTENSION);
wpabuf_put_u8(elem, 1 + wpabuf_len(sig));
wpabuf_put_u8(elem, WLAN_EID_EXT_FILS_KEY_CONFIRM);
/* KeyAuth = Sig_AP(eleAP || eleSTA || scaAP || scaSTA || M || K_AP ||
* AP-BSSID || STA-MAC) */
wpabuf_put_buf(elem, sig);
/* TODO: fragmentation */
extra = 6; /* Vendor specific element header */
if (wpabuf_tailroom(elem) < extra + wpabuf_len(buf)) {
wpa_printf(MSG_INFO,
"SAE-PK: No room in message buffer for SAE-PK element (%zu < %zu)",
wpabuf_tailroom(buf), extra + wpabuf_len(buf));
goto fail;
}
/* SAE-PK element */
wpabuf_put_u8(buf, WLAN_EID_VENDOR_SPECIFIC);
wpabuf_put_u8(buf, 4 + wpabuf_len(elem));
wpabuf_put_be32(buf, SAE_PK_IE_VENDOR_TYPE);
wpabuf_put_buf(buf, elem);
ret = 0;
fail:
wpabuf_free(elem);
wpabuf_free(sig);
return ret;
}
static bool sae_pk_valid_fingerprint(struct sae_data *sae,
const u8 *m, size_t m_len,
const u8 *k_ap, size_t k_ap_len)
{
struct sae_temporary_data *tmp = sae->tmp;
size_t sec, i;
u8 *fingerprint_exp, *hash_data, *pos;
size_t hash_len, hash_data_len, fingerprint_bits, fingerprint_bytes;
u8 hash[SAE_MAX_HASH_LEN];
int res;
if (!tmp->pw || tmp->pw_len < 1) {
wpa_printf(MSG_DEBUG,
"SAE-PK: No PW available for K_AP fingerprint check");
return false;
}
/* Fingerprint = L(Hash(SSID || M || K_AP), 0, 8*Sec + 5*Lambda - 2) */
hash_len = sae_ecc_prime_len_2_hash_len(tmp->prime_len);
hash_data_len = tmp->ssid_len + m_len + k_ap_len;
hash_data = os_malloc(hash_data_len);
if (!hash_data)
return false;
pos = hash_data;
os_memcpy(pos, tmp->ssid, tmp->ssid_len);
pos += tmp->ssid_len;
os_memcpy(pos, m, m_len);
pos += m_len;
os_memcpy(pos, k_ap, k_ap_len);
wpa_hexdump_key(MSG_DEBUG, "SAE-PK: SSID || M || K_AP",
hash_data, hash_data_len);
res = sae_hash(hash_len, hash_data, hash_data_len, hash);
bin_clear_free(hash_data, hash_data_len);
if (res < 0)
return false;
wpa_hexdump(MSG_DEBUG, "SAE-PK: Hash(SSID || M || K_AP)",
hash, hash_len);
wpa_hexdump_key(MSG_DEBUG, "SAE-PK: PW", tmp->pw, tmp->pw_len);
sec = (tmp->pw[0] >> 6) + 2;
fingerprint_bits = 8 * sec + 5 * tmp->lambda - 2;
wpa_printf(MSG_DEBUG, "SAE-PK: Sec=%zu Lambda=%zu fingerprint_bits=%zu",
sec, tmp->lambda, fingerprint_bits);
if (fingerprint_bits > hash_len * 8) {
wpa_printf(MSG_INFO,
"SAE-PK: Not enough hash output bits for the fingerprint");
return false;
}
fingerprint_bytes = (fingerprint_bits + 7) / 8;
if (fingerprint_bits % 8) {
size_t extra;
/* Zero out the extra bits in the last octet */
extra = 8 - fingerprint_bits % 8;
pos = &hash[fingerprint_bits / 8];
*pos = (*pos >> extra) << extra;
}
wpa_hexdump(MSG_DEBUG, "SAE-PK: Fingerprint", hash, fingerprint_bytes);
fingerprint_exp = os_zalloc(sec + tmp->pw_len);
if (!fingerprint_exp)
return false;
pos = fingerprint_exp + sec;
for (i = 0; i < tmp->pw_len; i++) {
u8 next = i + 1 < tmp->pw_len ? tmp->pw[i + 1] : 0;
*pos++ = tmp->pw[i] << 2 | next >> 6;
}
wpa_hexdump(MSG_DEBUG, "SAE-PK: Fingerprint_Expected",
fingerprint_exp, fingerprint_bytes);
res = os_memcmp_const(hash, fingerprint_exp, fingerprint_bytes);
bin_clear_free(fingerprint_exp, tmp->pw_len);
if (res) {
wpa_printf(MSG_DEBUG, "SAE-PK: K_AP fingerprint mismatch");
return false;
}
wpa_printf(MSG_DEBUG, "SAE-PK: Valid K_AP fingerprint");
return true;
}
int sae_check_confirm_pk(struct sae_data *sae, const u8 *ies, size_t ies_len)
{
struct sae_temporary_data *tmp = sae->tmp;
const u8 *sae_pk, *pos, *end, *encr_mod, *k_ap, *key_auth;
u8 m[SAE_PK_M_LEN];
size_t k_ap_len, key_auth_len;
struct crypto_ec_key *key;
int res;
u8 hash[SAE_MAX_HASH_LEN];
size_t hash_len;
int group;
if (!tmp)
return -1;
if (!tmp->pk || tmp->ap_pk)
return 0;
if (tmp->kek_len != 32 && tmp->kek_len != 48 && tmp->kek_len != 64) {
wpa_printf(MSG_INFO, "SAE-PK: No KEK available for confirm");
return -1;
}
if (!tmp->ec) {
/* Only ECC groups are supported for SAE-PK in the current
* implementation. */
wpa_printf(MSG_INFO,
"SAE-PK: SAE commit did not use an ECC group");
return -1;
}
wpa_hexdump(MSG_DEBUG, "SAE-PK: Received confirm IEs", ies, ies_len);
sae_pk = get_vendor_ie(ies, ies_len, SAE_PK_IE_VENDOR_TYPE);
if (!sae_pk) {
wpa_printf(MSG_INFO, "SAE-PK: No SAE-PK element included");
return -1;
}
/* TODO: Fragment reassembly */
pos = sae_pk + 2;
end = pos + sae_pk[1];
if (end - pos < 4 + 1 + SAE_PK_M_LEN + AES_BLOCK_SIZE) {
wpa_printf(MSG_INFO,
"SAE-PK: No room for EncryptedModifier in SAE-PK element");
return -1;
}
pos += 4;
if (*pos != SAE_PK_M_LEN + AES_BLOCK_SIZE) {
wpa_printf(MSG_INFO,
"SAE-PK: Unexpected EncryptedModifier length %u",
*pos);
return -1;
}
pos++;
encr_mod = pos;
pos += SAE_PK_M_LEN + AES_BLOCK_SIZE;
if (end - pos < 4 || pos[0] != WLAN_EID_EXTENSION || pos[1] < 2 ||
pos[1] > end - pos - 2 ||
pos[2] != WLAN_EID_EXT_FILS_PUBLIC_KEY) {
wpa_printf(MSG_INFO,
"SAE-PK: No FILS Public Key element in SAE-PK element");
return -1;
}
if (pos[3] != 3) {
wpa_printf(MSG_INFO, "SAE-PK: Unsupported public key type %u",
pos[3]);
return -1;
}
k_ap_len = pos[1] - 2;
pos += 4;
k_ap = pos;
pos += k_ap_len;
if (end - pos < 4 || pos[0] != WLAN_EID_EXTENSION || pos[1] < 1 ||
pos[1] > end - pos - 2 ||
pos[2] != WLAN_EID_EXT_FILS_KEY_CONFIRM) {
wpa_printf(MSG_INFO,
"SAE-PK: No FILS Key Confirm element in SAE-PK element");
return -1;
}
key_auth_len = pos[1] - 1;
pos += 3;
key_auth = pos;
pos += key_auth_len;
if (pos < end) {
wpa_hexdump(MSG_DEBUG,
"SAE-PK: Extra data at the end of SAE-PK element",
pos, end - pos);
}
wpa_hexdump(MSG_DEBUG, "SAE-PK: EncryptedModifier",
encr_mod, SAE_PK_M_LEN + AES_BLOCK_SIZE);
if (aes_siv_decrypt(tmp->kek, tmp->kek_len,
encr_mod, SAE_PK_M_LEN + AES_BLOCK_SIZE,
0, NULL, NULL, m) < 0) {
wpa_printf(MSG_INFO,
"SAE-PK: Failed to decrypt EncryptedModifier");
return -1;
}
wpa_hexdump_key(MSG_DEBUG, "SAE-PK: Modifier M", m, SAE_PK_M_LEN);
wpa_hexdump(MSG_DEBUG, "SAE-PK: Received K_AP", k_ap, k_ap_len);
/* TODO: Check against the public key, if one is stored in the network
* profile */
if (!sae_pk_valid_fingerprint(sae, m, SAE_PK_M_LEN, k_ap, k_ap_len))
return -1;
key = crypto_ec_key_parse_pub(k_ap, k_ap_len);
if (!key) {
wpa_printf(MSG_INFO, "SAE-PK: Failed to parse K_AP");
return -1;
}
group = crypto_ec_key_group(key);
/* TODO: Could support alternative groups as long as the combination
* meets the requirements. */
if (group != sae->group) {
wpa_printf(MSG_INFO,
"SAE-PK: K_AP group %d does not match SAE group %d",
group, sae->group);
crypto_ec_key_deinit(key);
return -1;
}
wpa_hexdump(MSG_DEBUG, "SAE-PK: Received KeyAuth",
key_auth, key_auth_len);
hash_len = sae_ecc_prime_len_2_hash_len(tmp->prime_len);
if (sae_pk_hash_sig_data(sae, hash_len, false, m, SAE_PK_M_LEN,
k_ap, k_ap_len, hash) < 0) {
crypto_ec_key_deinit(key);
return -1;
}
res = crypto_ec_key_verify_signature(key, hash, hash_len,
key_auth, key_auth_len);
crypto_ec_key_deinit(key);
if (res != 1) {
wpa_printf(MSG_INFO,
"SAE-PK: Invalid or incorrect signature in KeyAuth");
return -1;
}
wpa_printf(MSG_DEBUG, "SAE-PK: Valid KeyAuth signature received");
/* TODO: Store validated public key into network profile */
return 0;
}

4
wpa_supplicant/Android.mk
View File

@ -235,6 +235,10 @@ endif
ifdef CONFIG_SAE
L_CFLAGS += -DCONFIG_SAE
OBJS += src/common/sae.c
ifdef CONFIG_SAE_PK
L_CFLAGS += -DCONFIG_SAE_PK
OBJS += src/common/sae_pk.c
endif
NEED_ECC=y
NEED_DH_GROUPS=y
NEED_HMAC_SHA256_KDF=y

4
wpa_supplicant/Makefile
View File

@ -267,6 +267,10 @@ endif
ifdef CONFIG_SAE
CFLAGS += -DCONFIG_SAE
OBJS += ../src/common/sae.o
ifdef CONFIG_SAE_PK
CFLAGS += -DCONFIG_SAE_PK
OBJS += ../src/common/sae_pk.o
endif
NEED_ECC=y
NEED_DH_GROUPS=y
NEED_HMAC_SHA256_KDF=y

2
wpa_supplicant/sme.c
View File

@ -157,7 +157,7 @@ static struct wpabuf * sme_auth_build_sae_commit(struct wpa_supplicant *wpa_s,
if (use_pt &&
sae_prepare_commit_pt(&wpa_s->sme.sae, ssid->pt,
wpa_s->own_addr, bssid,
wpa_s->sme.sae_rejected_groups) < 0)
wpa_s->sme.sae_rejected_groups, NULL) < 0)
return NULL;
if (!use_pt &&
sae_prepare_commit(wpa_s->own_addr, bssid,