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AP: Support Extended Key ID

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Support Extended Key ID in hostapd according to IEEE Std 802.11-2016.

Extended Key ID allows to rekey pairwise keys without the otherwise
unavoidable MPDU losses on a busy link. The standard is fully backward
compatible, allowing an AP to serve STAs with and without Extended Key
ID support in the same BSS.

Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
This commit is contained in:
Alexander Wetzel 2020-03-20 20:04:31 +01:00 committed by Jouni Malinen
parent 9efac01020
commit 862aac1fcd
10 changed files with 130 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
hostapd/config_file.c
View File

@ -2869,6 +2869,16 @@ static int hostapd_config_fill(struct hostapd_config *conf,
}
} else if (os_strcmp(buf, "wpa") == 0) {
bss->wpa = atoi(pos);
} else if (os_strcmp(buf, "extended_key_id") == 0) {
int val = atoi(pos);
if (bss->extended_key_id < 0 || bss->extended_key_id > 2) {
wpa_printf(MSG_ERROR,
"Line %d: Invalid extended_key_id=%d; allowed range 0..2",
line, bss->extended_key_id);
return 1;
}
bss->extended_key_id = val;
} else if (os_strcmp(buf, "wpa_group_rekey") == 0) {
bss->wpa_group_rekey = atoi(pos);
bss->wpa_group_rekey_set = 1;

8
hostapd/ctrl_iface.c
View File

@ -1295,6 +1295,14 @@ static int hostapd_ctrl_iface_get_config(struct hostapd_data *hapd,
pos += ret;
}
if ((hapd->conf->wpa & WPA_PROTO_RSN) && hapd->conf->extended_key_id) {
ret = os_snprintf(pos, end - pos, "extended_key_id=%d\n",
hapd->conf->extended_key_id);
if (os_snprintf_error(end - pos, ret))
return pos - buf;
pos += ret;
}
return pos - buf;
}

11
hostapd/hostapd.conf
View File

@ -1510,6 +1510,17 @@ own_ip_addr=127.0.0.1
# wpa_key_mgmt=SAE for WPA3-Personal instead of wpa_key_mgmt=WPA-PSK).
#wpa=2
# Extended Key ID support for Individually Addressed frames
#
# Extended Key ID allows to rekey PTK keys without the impacts the "normal"
# PTK rekeying with only a single Key ID 0 has. It can only be used when the
# driver supports it and RSN/WPA2 is used with a CCMP/GCMP pairwise cipher.
#
# 0 = force off, i.e., use only Key ID 0 (default)
# 1 = enable and use Extended Key ID support when possible
# 2 = identical to 1 but start with Key ID 1 when possible
#extended_key_id=0
# WPA pre-shared keys for WPA-PSK. This can be either entered as a 256-bit
# secret in hex format (64 hex digits), wpa_psk, or as an ASCII passphrase
# (8..63 characters) that will be converted to PSK. This conversion uses SSID

1
src/ap/ap_config.h
View File

@ -354,6 +354,7 @@ struct hostapd_bss_config {
* algorithms, WPA_AUTH_ALG_{OPEN,SHARED,LEAP} */
int wpa; /* bitfield of WPA_PROTO_WPA, WPA_PROTO_RSN */
int extended_key_id;
int wpa_key_mgmt;
enum mfp_options ieee80211w;
int group_mgmt_cipher;

78
src/ap/wpa_auth.c
View File

@ -781,7 +781,7 @@ static void wpa_request_new_ptk(struct wpa_state_machine *sm)
if (sm == NULL)
return;
if (sm->wpa_auth->conf.wpa_deny_ptk0_rekey) {
if (!sm->use_ext_key_id && sm->wpa_auth->conf.wpa_deny_ptk0_rekey) {
wpa_printf(MSG_INFO,
"WPA: PTK0 rekey not allowed, disconnect " MACSTR,
MAC2STR(sm->addr));
@ -790,6 +790,8 @@ static void wpa_request_new_ptk(struct wpa_state_machine *sm)
sm->disconnect_reason =
WLAN_REASON_CLASS3_FRAME_FROM_NONASSOC_STA;
} else {
if (sm->use_ext_key_id)
sm->keyidx_active ^= 1; /* flip Key ID */
sm->PTKRequest = TRUE;
sm->PTK_valid = 0;
}
@ -1754,6 +1756,11 @@ void wpa_remove_ptk(struct wpa_state_machine *sm)
0, KEY_FLAG_PAIRWISE))
wpa_printf(MSG_DEBUG,
"RSN: PTK removal from the driver failed");
if (sm->wpa_auth->conf.extended_key_id && sm->use_ext_key_id &&
wpa_auth_set_key(sm->wpa_auth, 0, WPA_ALG_NONE, sm->addr, 1, NULL,
0, KEY_FLAG_PAIRWISE))
wpa_printf(MSG_DEBUG,
"RSN: PTK Key ID 1 removal from the driver failed");
sm->pairwise_set = FALSE;
eloop_cancel_timeout(wpa_rekey_ptk, sm->wpa_auth, sm);
}
@ -1812,16 +1819,23 @@ int wpa_auth_sm_event(struct wpa_state_machine *sm, enum wpa_event event)
sm->Init = FALSE;
sm->AuthenticationRequest = TRUE;
break;
} else if (sm->wpa_auth->conf.wpa_deny_ptk0_rekey) {
}
if (!sm->use_ext_key_id &&
sm->wpa_auth->conf.wpa_deny_ptk0_rekey) {
wpa_printf(MSG_INFO,
"WPA: PTK0 rekey not allowed, disconnect "
MACSTR, MAC2STR(sm->addr));
sm->Disconnect = TRUE;
/* Try to encourage the STA reconnect */
/* Try to encourage the STA to reconnect */
sm->disconnect_reason =
WLAN_REASON_CLASS3_FRAME_FROM_NONASSOC_STA;
break;
}
if (sm->use_ext_key_id)
sm->keyidx_active ^= 1; /* flip Key ID */
if (sm->GUpdateStationKeys) {
/*
* Reauthentication cancels the pending group key
@ -3261,6 +3275,7 @@ SM_STATE(WPA_PTK, PTKINITNEGOTIATING)
u8 *wpa_ie;
int secure, gtkidx, encr = 0;
u8 *wpa_ie_buf = NULL, *wpa_ie_buf2 = NULL;
u8 hdr[2];
SM_ENTRY_MA(WPA_PTK, PTKINITNEGOTIATING, wpa_ptk);
sm->TimeoutEvt = FALSE;
@ -3317,6 +3332,18 @@ SM_STATE(WPA_PTK, PTKINITNEGOTIATING)
wpa_auth_logger(sm->wpa_auth, sm->addr, LOGGER_DEBUG,
"sending 3/4 msg of 4-Way Handshake");
if (sm->wpa == WPA_VERSION_WPA2) {
if (sm->use_ext_key_id && sm->TimeoutCtr == 1 &&
wpa_auth_set_key(sm->wpa_auth, 0,
wpa_cipher_to_alg(sm->pairwise),
sm->addr,
sm->keyidx_active, sm->PTK.tk,
wpa_cipher_key_len(sm->pairwise),
KEY_FLAG_PAIRWISE_RX)) {
wpa_sta_disconnect(sm->wpa_auth, sm->addr,
WLAN_REASON_PREV_AUTH_NOT_VALID);
return;
}
/* WPA2 send GTK in the 4-way handshake */
secure = 1;
gtk = gsm->GTK[gsm->GN - 1];
@ -3357,6 +3384,10 @@ SM_STATE(WPA_PTK, PTKINITNEGOTIATING)
}
kde_len = wpa_ie_len + ieee80211w_kde_len(sm) + ocv_oci_len(sm);
if (sm->use_ext_key_id)
kde_len += 2 + RSN_SELECTOR_LEN + 2;
if (gtk)
kde_len += 2 + RSN_SELECTOR_LEN + 2 + gtk_len;
#ifdef CONFIG_IEEE80211R_AP
@ -3392,10 +3423,15 @@ SM_STATE(WPA_PTK, PTKINITNEGOTIATING)
pos += elen;
}
#endif /* CONFIG_IEEE80211R_AP */
if (gtk) {
u8 hdr[2];
hdr[0] = gtkidx & 0x03;
hdr[1] = 0;
if (sm->use_ext_key_id) {
hdr[0] = sm->keyidx_active & 0x01;
pos = wpa_add_kde(pos, RSN_KEY_DATA_KEYID, hdr, 2, NULL, 0);
}
if (gtk) {
hdr[0] = gtkidx & 0x03;
pos = wpa_add_kde(pos, RSN_KEY_DATA_GROUPKEY, hdr, 2,
gtk, gtk_len);
}
@ -3478,9 +3514,17 @@ SM_STATE(WPA_PTK, PTKINITDONE)
if (sm->Pair) {
enum wpa_alg alg = wpa_cipher_to_alg(sm->pairwise);
int klen = wpa_cipher_key_len(sm->pairwise);
if (wpa_auth_set_key(sm->wpa_auth, 0, alg, sm->addr, 0,
sm->PTK.tk, klen,
KEY_FLAG_PAIRWISE_RX_TX)) {
int res;
if (sm->use_ext_key_id)
res = wpa_auth_set_key(sm->wpa_auth, 0, 0, sm->addr,
sm->keyidx_active, NULL, 0,
KEY_FLAG_PAIRWISE_RX_TX_MODIFY);
else
res = wpa_auth_set_key(sm->wpa_auth, 0, alg, sm->addr,
0, sm->PTK.tk, klen,
KEY_FLAG_PAIRWISE_RX_TX);
if (res) {
wpa_sta_disconnect(sm->wpa_auth, sm->addr,
WLAN_REASON_PREV_AUTH_NOT_VALID);
return;
@ -5167,6 +5211,7 @@ int wpa_auth_resend_m3(struct wpa_state_machine *sm,
struct wpa_group *gsm = sm->group;
u8 *wpa_ie;
int wpa_ie_len, secure, gtkidx, encr = 0;
u8 hdr[2];
/* Send EAPOL(1, 1, 1, Pair, P, RSC, ANonce, MIC(PTK), RSNIE, [MDIE],
GTK[GN], IGTK, [BIGTK], [FTIE], [TIE * 2])
@ -5219,6 +5264,10 @@ int wpa_auth_resend_m3(struct wpa_state_machine *sm,
}
kde_len = wpa_ie_len + ieee80211w_kde_len(sm) + ocv_oci_len(sm);
if (sm->use_ext_key_id)
kde_len += 2 + RSN_SELECTOR_LEN + 2;
if (gtk)
kde_len += 2 + RSN_SELECTOR_LEN + 2 + gtk_len;
#ifdef CONFIG_IEEE80211R_AP
@ -5251,10 +5300,15 @@ int wpa_auth_resend_m3(struct wpa_state_machine *sm,
pos += elen;
}
#endif /* CONFIG_IEEE80211R_AP */
if (gtk) {
u8 hdr[2];
hdr[0] = gtkidx & 0x03;
hdr[1] = 0;
if (sm->use_ext_key_id) {
hdr[0] = sm->keyidx_active & 0x01;
pos = wpa_add_kde(pos, RSN_KEY_DATA_KEYID, hdr, 2, NULL, 0);
}
if (gtk) {
hdr[0] = gtkidx & 0x03;
pos = wpa_add_kde(pos, RSN_KEY_DATA_GROUPKEY, hdr, 2,
gtk, gtk_len);
}

1
src/ap/wpa_auth.h
View File

@ -169,6 +169,7 @@ struct ft_remote_r1kh {
struct wpa_auth_config {
int wpa;
int extended_key_id;
int wpa_key_mgmt;
int wpa_pairwise;
int wpa_group;

2
src/ap/wpa_auth_ft.c
View File

@ -2775,7 +2775,7 @@ void wpa_ft_install_ptk(struct wpa_state_machine *sm)
* again after association to get the PTK configured, but that could be
* optimized by adding the STA entry earlier.
*/
if (wpa_auth_set_key(sm->wpa_auth, 0, alg, sm->addr, 0,
if (wpa_auth_set_key(sm->wpa_auth, 0, alg, sm->addr, sm->keyidx_active,
sm->PTK.tk, klen, KEY_FLAG_PAIRWISE_RX_TX))
return;

13
src/ap/wpa_auth_glue.c
View File

@ -41,6 +41,7 @@ static void hostapd_wpa_auth_conf(struct hostapd_bss_config *conf,
os_memset(wconf, 0, sizeof(*wconf));
wconf->wpa = conf->wpa;
wconf->extended_key_id = conf->extended_key_id;
wconf->wpa_key_mgmt = conf->wpa_key_mgmt;
wconf->wpa_pairwise = conf->wpa_pairwise;
wconf->wpa_group = conf->wpa_group;
@ -433,7 +434,11 @@ static int hostapd_wpa_auth_set_key(void *ctx, int vlan_id, enum wpa_alg alg,
}
#ifdef CONFIG_TESTING_OPTIONS
if (addr && !is_broadcast_ether_addr(addr)) {
if (key_flag & KEY_FLAG_MODIFY) {
/* We are updating an already installed key. Don't overwrite
* the already stored key information with zeros.
*/
} else if (addr && !is_broadcast_ether_addr(addr)) {
struct sta_info *sta;
sta = ap_get_sta(hapd, addr);
@ -1419,6 +1424,12 @@ int hostapd_setup_wpa(struct hostapd_data *hapd)
_conf.wpa_deny_ptk0_rekey = 1;
}
if (_conf.extended_key_id &&
(hapd->iface->drv_flags & WPA_DRIVER_FLAGS_EXTENDED_KEY_ID))
wpa_msg(hapd->msg_ctx, MSG_DEBUG, "Extended Key ID supported");
else
_conf.extended_key_id = 0;
hapd->wpa_auth = wpa_init(hapd->own_addr, &_conf, &cb, hapd);
if (hapd->wpa_auth == NULL) {
wpa_printf(MSG_ERROR, "WPA initialization failed.");

2
src/ap/wpa_auth_i.h
View File

@ -61,6 +61,8 @@ struct wpa_state_machine {
unsigned int pmk_len;
u8 pmkid[PMKID_LEN]; /* valid if pmkid_set == 1 */
struct wpa_ptk PTK;
u8 keyidx_active;
Boolean use_ext_key_id;
Boolean PTK_valid;
Boolean pairwise_set;
Boolean tk_already_set;

20
src/ap/wpa_auth_ie.c
View File

@ -297,6 +297,8 @@ int wpa_write_rsn_ie(struct wpa_auth_config *conf, u8 *buf, size_t len,
if (rsn_testing)
capab |= BIT(8) | BIT(15);
#endif /* CONFIG_RSN_TESTING */
if (conf->extended_key_id)
capab |= WPA_CAPABILITY_EXT_KEY_ID_FOR_UNICAST;
WPA_PUT_LE16(pos, capab);
pos += 2;
@ -553,6 +555,7 @@ int wpa_validate_wpa_ie(struct wpa_authenticator *wpa_auth,
const u8 *mdie, size_t mdie_len,
const u8 *owe_dh, size_t owe_dh_len)
{
struct wpa_auth_config *conf = &wpa_auth->conf;
struct wpa_ie_data data;
int ciphers, key_mgmt, res, version;
u32 selector;
@ -944,6 +947,23 @@ int wpa_validate_wpa_ie(struct wpa_authenticator *wpa_auth,
}
#endif /* CONFIG_DPP */
if (conf->extended_key_id && sm->wpa == WPA_VERSION_WPA2 &&
sm->pairwise != WPA_CIPHER_TKIP &&
(data.capabilities & WPA_CAPABILITY_EXT_KEY_ID_FOR_UNICAST)) {
sm->use_ext_key_id = TRUE;
if (conf->extended_key_id == 2 &&
!wpa_key_mgmt_ft(sm->wpa_key_mgmt) &&
!wpa_key_mgmt_fils(sm->wpa_key_mgmt))
sm->keyidx_active = 1;
else
sm->keyidx_active = 0;
wpa_printf(MSG_DEBUG,
"RSN: Extended Key ID supported (start with %d)",
sm->keyidx_active);
} else {
sm->use_ext_key_id = FALSE;
}
if (sm->wpa_ie == NULL || sm->wpa_ie_len < wpa_ie_len) {
os_free(sm->wpa_ie);
sm->wpa_ie = os_malloc(wpa_ie_len);