hostap/wpa_supplicant/mesh_rsn.c
Jouni Malinen 608b0ff52a mesh: Check for initialization failures
It is possible that these location ended up getting called before mesh
startup operations had been completed and that could result in
dereferencing NULL pointers. Address those error cases by verifying that
the needed parameters are available before using them.

Signed-off-by: Jouni Malinen <j@w1.fi>
2014-11-30 15:53:11 +02:00

614 lines
15 KiB
C

/*
* WPA Supplicant - Mesh RSN routines
* Copyright (c) 2013-2014, cozybit, Inc. All rights reserved.
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "utils/includes.h"
#include "utils/common.h"
#include "utils/eloop.h"
#include "crypto/sha256.h"
#include "crypto/random.h"
#include "crypto/aes.h"
#include "crypto/aes_siv.h"
#include "rsn_supp/wpa.h"
#include "ap/hostapd.h"
#include "ap/wpa_auth.h"
#include "ap/sta_info.h"
#include "wpa_supplicant_i.h"
#include "driver_i.h"
#include "wpas_glue.h"
#include "mesh_mpm.h"
#include "mesh_rsn.h"
#define MESH_AUTH_TIMEOUT 10
#define MESH_AUTH_RETRY 3
void mesh_auth_timer(void *eloop_ctx, void *user_data)
{
struct wpa_supplicant *wpa_s = eloop_ctx;
struct sta_info *sta = user_data;
if (sta->sae->state != SAE_ACCEPTED) {
wpa_printf(MSG_DEBUG, "AUTH: Re-authenticate with " MACSTR
" (attempt %d) ",
MAC2STR(sta->addr), sta->sae_auth_retry);
if (sta->sae_auth_retry < MESH_AUTH_RETRY) {
mesh_rsn_auth_sae_sta(wpa_s, sta);
} else {
/* block the STA if exceeded the number of attempts */
sta->plink_state = PLINK_BLOCKED;
sta->sae->state = SAE_NOTHING;
}
sta->sae_auth_retry++;
}
}
static void auth_logger(void *ctx, const u8 *addr, logger_level level,
const char *txt)
{
if (addr)
wpa_printf(MSG_DEBUG, "AUTH: " MACSTR " - %s",
MAC2STR(addr), txt);
else
wpa_printf(MSG_DEBUG, "AUTH: %s", txt);
}
static const u8 *auth_get_psk(void *ctx, const u8 *addr,
const u8 *p2p_dev_addr, const u8 *prev_psk)
{
struct mesh_rsn *mesh_rsn = ctx;
struct hostapd_data *hapd = mesh_rsn->wpa_s->ifmsh->bss[0];
struct sta_info *sta = ap_get_sta(hapd, addr);
wpa_printf(MSG_DEBUG, "AUTH: %s (addr=" MACSTR " prev_psk=%p)",
__func__, MAC2STR(addr), prev_psk);
if (sta && sta->auth_alg == WLAN_AUTH_SAE) {
if (!sta->sae || prev_psk)
return NULL;
return sta->sae->pmk;
}
return NULL;
}
static int auth_set_key(void *ctx, int vlan_id, enum wpa_alg alg,
const u8 *addr, int idx, u8 *key, size_t key_len)
{
struct mesh_rsn *mesh_rsn = ctx;
u8 seq[6];
os_memset(seq, 0, sizeof(seq));
if (addr) {
wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d addr=" MACSTR
" key_idx=%d)",
__func__, alg, MAC2STR(addr), idx);
} else {
wpa_printf(MSG_DEBUG, "AUTH: %s(alg=%d key_idx=%d)",
__func__, alg, idx);
}
wpa_hexdump_key(MSG_DEBUG, "AUTH: set_key - key", key, key_len);
return wpa_drv_set_key(mesh_rsn->wpa_s, alg, addr, idx,
1, seq, 6, key, key_len);
}
static int auth_start_ampe(void *ctx, const u8 *addr)
{
struct mesh_rsn *mesh_rsn = ctx;
struct hostapd_data *hapd;
struct sta_info *sta;
if (mesh_rsn->wpa_s->current_ssid->mode != WPAS_MODE_MESH)
return -1;
hapd = mesh_rsn->wpa_s->ifmsh->bss[0];
sta = ap_get_sta(hapd, addr);
if (sta)
eloop_cancel_timeout(mesh_auth_timer, mesh_rsn->wpa_s, sta);
mesh_mpm_auth_peer(mesh_rsn->wpa_s, addr);
return 0;
}
static int __mesh_rsn_auth_init(struct mesh_rsn *rsn, const u8 *addr)
{
struct wpa_auth_config conf;
struct wpa_auth_callbacks cb;
u8 seq[6] = {};
wpa_printf(MSG_DEBUG, "AUTH: Initializing group state machine");
os_memset(&conf, 0, sizeof(conf));
conf.wpa = 2;
conf.wpa_key_mgmt = WPA_KEY_MGMT_SAE;
conf.wpa_pairwise = WPA_CIPHER_CCMP;
conf.rsn_pairwise = WPA_CIPHER_CCMP;
conf.wpa_group = WPA_CIPHER_CCMP;
conf.eapol_version = 0;
conf.wpa_group_rekey = -1;
os_memset(&cb, 0, sizeof(cb));
cb.ctx = rsn;
cb.logger = auth_logger;
cb.get_psk = auth_get_psk;
cb.set_key = auth_set_key;
cb.start_ampe = auth_start_ampe;
rsn->auth = wpa_init(addr, &conf, &cb);
if (rsn->auth == NULL) {
wpa_printf(MSG_DEBUG, "AUTH: wpa_init() failed");
return -1;
}
/* TODO: support rekeying */
if (random_get_bytes(rsn->mgtk, 16) < 0) {
wpa_deinit(rsn->auth);
return -1;
}
/* group mgmt */
wpa_drv_set_key(rsn->wpa_s, WPA_ALG_IGTK, NULL, 4, 1,
seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk));
/* group privacy / data frames */
wpa_drv_set_key(rsn->wpa_s, WPA_ALG_CCMP, NULL, 1, 1,
seq, sizeof(seq), rsn->mgtk, sizeof(rsn->mgtk));
return 0;
}
static void mesh_rsn_deinit(struct mesh_rsn *rsn)
{
os_memset(rsn->mgtk, 0, sizeof(rsn->mgtk));
wpa_deinit(rsn->auth);
}
struct mesh_rsn *mesh_rsn_auth_init(struct wpa_supplicant *wpa_s,
struct mesh_conf *conf)
{
struct mesh_rsn *mesh_rsn;
struct hostapd_data *bss = wpa_s->ifmsh->bss[0];
const u8 *ie;
size_t ie_len;
mesh_rsn = os_zalloc(sizeof(*mesh_rsn));
if (mesh_rsn == NULL)
return NULL;
mesh_rsn->wpa_s = wpa_s;
if (__mesh_rsn_auth_init(mesh_rsn, wpa_s->own_addr) < 0) {
mesh_rsn_deinit(mesh_rsn);
return NULL;
}
bss->wpa_auth = mesh_rsn->auth;
ie = wpa_auth_get_wpa_ie(mesh_rsn->auth, &ie_len);
conf->ies = (u8 *) ie;
conf->ie_len = ie_len;
wpa_supplicant_rsn_supp_set_config(wpa_s, wpa_s->current_ssid);
return mesh_rsn;
}
static int index_within_array(const int *array, int idx)
{
int i;
for (i = 0; i < idx; i++) {
if (array[i] == -1)
return 0;
}
return 1;
}
static int mesh_rsn_sae_group(struct wpa_supplicant *wpa_s,
struct sae_data *sae)
{
int *groups = wpa_s->ifmsh->bss[0]->conf->sae_groups;
/* Configuration may have changed, so validate current index */
if (!index_within_array(groups, wpa_s->mesh_rsn->sae_group_index))
return -1;
for (;;) {
int group = groups[wpa_s->mesh_rsn->sae_group_index];
if (group <= 0)
break;
if (sae_set_group(sae, group) == 0) {
wpa_dbg(wpa_s, MSG_DEBUG, "SME: Selected SAE group %d",
sae->group);
return 0;
}
wpa_s->mesh_rsn->sae_group_index++;
}
return -1;
}
struct wpabuf *
mesh_rsn_build_sae_commit(struct wpa_supplicant *wpa_s,
struct wpa_ssid *ssid, struct sta_info *sta)
{
struct wpabuf *buf;
int len;
if (ssid->passphrase == NULL) {
wpa_msg(wpa_s, MSG_DEBUG, "SAE: No password available");
return NULL;
}
if (mesh_rsn_sae_group(wpa_s, sta->sae) < 0) {
wpa_msg(wpa_s, MSG_DEBUG, "SAE: Failed to select group");
return NULL;
}
if (sae_prepare_commit(wpa_s->own_addr, sta->addr,
(u8 *) ssid->passphrase,
os_strlen(ssid->passphrase), sta->sae) < 0) {
wpa_msg(wpa_s, MSG_DEBUG, "SAE: Could not pick PWE");
return NULL;
}
len = wpa_s->mesh_rsn->sae_token ?
wpabuf_len(wpa_s->mesh_rsn->sae_token) : 0;
buf = wpabuf_alloc(4 + SAE_COMMIT_MAX_LEN + len);
if (buf == NULL)
return NULL;
sae_write_commit(sta->sae, buf, wpa_s->mesh_rsn->sae_token);
return buf;
}
static void mesh_rsn_send_auth(struct wpa_supplicant *wpa_s,
const u8 *dst, const u8 *src,
u16 auth_transaction, u16 resp,
struct wpabuf *data)
{
struct ieee80211_mgmt *auth;
u8 *buf;
size_t len, ielen = 0;
if (data)
ielen = wpabuf_len(data);
len = IEEE80211_HDRLEN + sizeof(auth->u.auth) + ielen;
buf = os_zalloc(len);
if (buf == NULL)
return;
auth = (struct ieee80211_mgmt *) buf;
auth->frame_control = IEEE80211_FC(WLAN_FC_TYPE_MGMT,
WLAN_FC_STYPE_AUTH);
os_memcpy(auth->da, dst, ETH_ALEN);
os_memcpy(auth->sa, src, ETH_ALEN);
os_memcpy(auth->bssid, src, ETH_ALEN);
auth->u.auth.auth_alg = host_to_le16(WLAN_AUTH_SAE);
auth->u.auth.auth_transaction = host_to_le16(auth_transaction);
auth->u.auth.status_code = host_to_le16(resp);
if (data)
os_memcpy(auth->u.auth.variable, wpabuf_head(data), ielen);
wpa_msg(wpa_s, MSG_DEBUG, "authentication frame: STA=" MACSTR
" auth_transaction=%d resp=%d (IE len=%lu)",
MAC2STR(dst), auth_transaction, resp, (unsigned long) ielen);
if (wpa_drv_send_mlme(wpa_s, buf, len, 0) < 0)
perror("send_auth_reply: send");
os_free(buf);
}
/* initiate new SAE authentication with sta */
int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s,
struct sta_info *sta)
{
struct wpa_ssid *ssid = wpa_s->current_ssid;
struct wpabuf *buf;
unsigned int rnd;
if (!ssid) {
wpa_msg(wpa_s, MSG_DEBUG,
"AUTH: No current_ssid known to initiate new SAE");
return -1;
}
if (!sta->sae) {
sta->sae = os_zalloc(sizeof(*sta->sae));
if (sta->sae == NULL)
return -1;
}
buf = mesh_rsn_build_sae_commit(wpa_s, ssid, sta);
if (!buf)
return -1;
wpa_msg(wpa_s, MSG_DEBUG,
"AUTH: started authentication with SAE peer: " MACSTR,
MAC2STR(sta->addr));
sta->sae->state = SAE_COMMITTED;
wpa_supplicant_set_state(wpa_s, WPA_AUTHENTICATING);
mesh_rsn_send_auth(wpa_s, sta->addr, wpa_s->own_addr,
1, WLAN_STATUS_SUCCESS, buf);
rnd = rand() % MESH_AUTH_TIMEOUT;
eloop_register_timeout(MESH_AUTH_TIMEOUT + rnd, 0, mesh_auth_timer,
wpa_s, sta);
wpabuf_free(buf);
return 0;
}
void mesh_rsn_get_pmkid(struct mesh_rsn *rsn, struct sta_info *sta, u8 *pmkid)
{
/* don't expect wpa auth to cache the pmkid for now */
rsn_pmkid(sta->sae->pmk, PMK_LEN, rsn->wpa_s->own_addr,
sta->addr, pmkid,
wpa_key_mgmt_sha256(wpa_auth_sta_key_mgmt(sta->wpa_sm)));
}
static void
mesh_rsn_derive_aek(struct mesh_rsn *rsn, struct sta_info *sta)
{
u8 *myaddr = rsn->wpa_s->own_addr;
u8 *peer = sta->addr;
u8 *addr1 = peer, *addr2 = myaddr;
u8 context[AES_BLOCK_SIZE];
/* SAE */
RSN_SELECTOR_PUT(context, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP));
if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) {
addr1 = myaddr;
addr2 = peer;
}
os_memcpy(context + 4, addr1, ETH_ALEN);
os_memcpy(context + 10, addr2, ETH_ALEN);
sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk), "AEK Derivation",
context, sizeof(context), sta->aek, sizeof(sta->aek));
}
/* derive mesh temporal key from pmk */
int mesh_rsn_derive_mtk(struct wpa_supplicant *wpa_s, struct sta_info *sta)
{
u8 *ptr;
u8 *min, *max;
u16 min_lid, max_lid;
size_t nonce_len = sizeof(sta->my_nonce);
size_t lid_len = sizeof(sta->my_lid);
u8 *myaddr = wpa_s->own_addr;
u8 *peer = sta->addr;
/* 2 nonces, 2 linkids, akm suite, 2 mac addrs */
u8 context[64 + 4 + 4 + 12];
ptr = context;
if (os_memcmp(sta->my_nonce, sta->peer_nonce, nonce_len) < 0) {
min = sta->my_nonce;
max = sta->peer_nonce;
} else {
min = sta->peer_nonce;
max = sta->my_nonce;
}
os_memcpy(ptr, min, nonce_len);
os_memcpy(ptr + nonce_len, max, nonce_len);
ptr += 2 * nonce_len;
if (sta->my_lid < sta->peer_lid) {
min_lid = host_to_le16(sta->my_lid);
max_lid = host_to_le16(sta->peer_lid);
} else {
min_lid = host_to_le16(sta->peer_lid);
max_lid = host_to_le16(sta->my_lid);
}
os_memcpy(ptr, &min_lid, lid_len);
os_memcpy(ptr + lid_len, &max_lid, lid_len);
ptr += 2 * lid_len;
/* SAE */
RSN_SELECTOR_PUT(ptr, wpa_cipher_to_suite(0, WPA_CIPHER_GCMP));
ptr += 4;
if (os_memcmp(myaddr, peer, ETH_ALEN) < 0) {
min = myaddr;
max = peer;
} else {
min = peer;
max = myaddr;
}
os_memcpy(ptr, min, ETH_ALEN);
os_memcpy(ptr + ETH_ALEN, max, ETH_ALEN);
sha256_prf(sta->sae->pmk, sizeof(sta->sae->pmk),
"Temporal Key Derivation", context, sizeof(context),
sta->mtk, sizeof(sta->mtk));
return 0;
}
void mesh_rsn_init_ampe_sta(struct wpa_supplicant *wpa_s, struct sta_info *sta)
{
if (random_get_bytes(sta->my_nonce, 32) < 0) {
wpa_printf(MSG_INFO, "mesh: Failed to derive random nonce");
/* TODO: How to handle this more cleanly? */
}
os_memset(sta->peer_nonce, 0, 32);
mesh_rsn_derive_aek(wpa_s->mesh_rsn, sta);
}
/* insert AMPE and encrypted MIC at @ie.
* @mesh_rsn: mesh RSN context
* @sta: STA we're sending to
* @cat: pointer to category code in frame header.
* @buf: wpabuf to add encrypted AMPE and MIC to.
* */
int mesh_rsn_protect_frame(struct mesh_rsn *rsn, struct sta_info *sta,
const u8 *cat, struct wpabuf *buf)
{
struct ieee80211_ampe_ie *ampe;
u8 const *ie = wpabuf_head_u8(buf) + wpabuf_len(buf);
u8 *ampe_ie = NULL, *mic_ie = NULL, *mic_payload;
const u8 *aad[] = { rsn->wpa_s->own_addr, sta->addr, cat };
const size_t aad_len[] = { ETH_ALEN, ETH_ALEN, ie - cat };
int ret = 0;
if (AES_BLOCK_SIZE + 2 + sizeof(*ampe) + 2 > wpabuf_tailroom(buf)) {
wpa_printf(MSG_ERROR, "protect frame: buffer too small");
return -EINVAL;
}
ampe_ie = os_zalloc(2 + sizeof(*ampe));
if (!ampe_ie) {
wpa_printf(MSG_ERROR, "protect frame: out of memory");
return -ENOMEM;
}
mic_ie = os_zalloc(2 + AES_BLOCK_SIZE);
if (!mic_ie) {
wpa_printf(MSG_ERROR, "protect frame: out of memory");
ret = -ENOMEM;
goto free;
}
/* IE: AMPE */
ampe_ie[0] = WLAN_EID_AMPE;
ampe_ie[1] = sizeof(*ampe);
ampe = (struct ieee80211_ampe_ie *) (ampe_ie + 2);
RSN_SELECTOR_PUT(ampe->selected_pairwise_suite,
wpa_cipher_to_suite(WPA_PROTO_RSN, WPA_CIPHER_CCMP));
os_memcpy(ampe->local_nonce, sta->my_nonce, 32);
os_memcpy(ampe->peer_nonce, sta->peer_nonce, 32);
/* incomplete: see 13.5.4 */
/* TODO: static mgtk for now since we don't support rekeying! */
os_memcpy(ampe->mgtk, rsn->mgtk, 16);
/* TODO: Populate Key RSC */
/* expire in 13 decades or so */
os_memset(ampe->key_expiration, 0xff, 4);
/* IE: MIC */
mic_ie[0] = WLAN_EID_MIC;
mic_ie[1] = AES_BLOCK_SIZE;
wpabuf_put_data(buf, mic_ie, 2);
/* MIC field is output ciphertext */
/* encrypt after MIC */
mic_payload = (u8 *) wpabuf_put(buf, 2 + sizeof(*ampe) +
AES_BLOCK_SIZE);
if (aes_siv_encrypt(sta->aek, ampe_ie, 2 + sizeof(*ampe), 3,
aad, aad_len, mic_payload)) {
wpa_printf(MSG_ERROR, "protect frame: failed to encrypt");
ret = -ENOMEM;
goto free;
}
free:
os_free(ampe_ie);
os_free(mic_ie);
return ret;
}
int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta,
struct ieee802_11_elems *elems, const u8 *cat,
const u8 *start, size_t elems_len)
{
int ret = 0;
struct ieee80211_ampe_ie *ampe;
u8 null_nonce[32] = {};
u8 ampe_eid;
u8 ampe_ie_len;
u8 *ampe_buf, *crypt = NULL;
size_t crypt_len;
const u8 *aad[] = { sta->addr, wpa_s->own_addr, cat };
const size_t aad_len[] = { ETH_ALEN, ETH_ALEN,
(elems->mic - 2) - cat };
if (!elems->mic || elems->mic_len < AES_BLOCK_SIZE) {
wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing mic ie");
return -1;
}
ampe_buf = (u8 *) elems->mic + elems->mic_len;
if ((int) elems_len < ampe_buf - start)
return -1;
crypt_len = elems_len - (elems->mic - start);
if (crypt_len < 2) {
wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: missing ampe ie");
return -1;
}
/* crypt is modified by siv_decrypt */
crypt = os_zalloc(crypt_len);
if (!crypt) {
wpa_printf(MSG_ERROR, "Mesh RSN: out of memory");
ret = -ENOMEM;
goto free;
}
os_memcpy(crypt, elems->mic, crypt_len);
if (aes_siv_decrypt(sta->aek, crypt, crypt_len, 3,
aad, aad_len, ampe_buf)) {
wpa_printf(MSG_ERROR, "Mesh RSN: frame verification failed!");
ret = -1;
goto free;
}
ampe_eid = *ampe_buf++;
ampe_ie_len = *ampe_buf++;
if (ampe_eid != WLAN_EID_AMPE ||
ampe_ie_len < sizeof(struct ieee80211_ampe_ie)) {
wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid ampe ie");
ret = -1;
goto free;
}
ampe = (struct ieee80211_ampe_ie *) ampe_buf;
if (os_memcmp(ampe->peer_nonce, null_nonce, 32) != 0 &&
os_memcmp(ampe->peer_nonce, sta->my_nonce, 32) != 0) {
wpa_msg(wpa_s, MSG_DEBUG, "Mesh RSN: invalid peer nonce");
ret = -1;
goto free;
}
os_memcpy(sta->peer_nonce, ampe->local_nonce,
sizeof(ampe->local_nonce));
os_memcpy(sta->mgtk, ampe->mgtk, sizeof(ampe->mgtk));
/* todo parse mgtk expiration */
free:
os_free(crypt);
return ret;
}