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ap: Handle PTK handshake frame 4/4

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Handle the 4-Way Handshake last frame, install keys, enable data frames
on the controlled port.
This commit is contained in:
Andrew Zaborowski 2017-09-22 05:06:43 +02:00 committed by Denis Kenzior
parent a3361c5077
commit 251edd2557
1 changed files with 167 additions and 0 deletions
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167
src/ap.c
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@ -65,6 +65,7 @@ struct ap_state {
struct sta_state {
uint8_t addr[6];
bool associated;
bool rsna;
uint16_t aid;
struct mmpdu_field_capability capability;
uint16_t listen_interval;
@ -138,18 +139,143 @@ static bool ap_sta_match_addr(const void *a, const void *b)
return !memcmp(sta->addr, b, 6);
}
static void ap_set_sta_cb(struct l_genl_msg *msg, void *user_data)
{
if (l_genl_msg_get_error(msg) < 0)
l_error("SET_STATION failed: %i", l_genl_msg_get_error(msg));
}
static void ap_del_sta_cb(struct l_genl_msg *msg, void *user_data)
{
if (l_genl_msg_get_error(msg) < 0)
l_error("DEL_STATION failed: %i", l_genl_msg_get_error(msg));
}
static void ap_new_key_cb(struct l_genl_msg *msg, void *user_data)
{
if (l_genl_msg_get_error(msg) < 0)
l_error("NEW_KEY failed: %i", l_genl_msg_get_error(msg));
}
static void ap_del_key_cb(struct l_genl_msg *msg, void *user_data)
{
if (l_genl_msg_get_error(msg) < 0)
l_debug("DEL_KEY failed: %i", l_genl_msg_get_error(msg));
}
static void ap_new_rsna(struct ap_state *ap, struct sta_state *sta)
{
struct l_genl_msg *msg;
uint32_t ifindex = device_get_ifindex(ap->device);
struct nl80211_sta_flag_update flags = {
.mask = (1 << NL80211_STA_FLAG_AUTHORIZED) |
(1 << NL80211_STA_FLAG_MFP),
.set = (1 << NL80211_STA_FLAG_AUTHORIZED),
};
uint8_t key_id = 0;
const struct crypto_ptk *ptk = (struct crypto_ptk *) sta->ptk;
uint32_t cipher = ie_rsn_cipher_suite_to_cipher(ap->ciphers);
uint32_t key_type = NL80211_KEYTYPE_PAIRWISE;
uint8_t tk_buf[32];
msg = l_genl_msg_new_sized(NL80211_CMD_SET_STATION, 128);
l_genl_msg_append_attr(msg, NL80211_ATTR_IFINDEX, 4, &ifindex);
l_genl_msg_append_attr(msg, NL80211_ATTR_MAC, 6, sta->addr);
l_genl_msg_append_attr(msg, NL80211_ATTR_STA_FLAGS2, 8, &flags);
if (!l_genl_family_send(nl80211, msg, ap_set_sta_cb, NULL, NULL)) {
l_genl_msg_unref(msg);
l_error("Issuing SET_STATION failed");
return;
}
sta->rsna = true;
switch (cipher) {
case CRYPTO_CIPHER_CCMP:
/*
* 802.11-2016 12.8.3 Mapping PTK to CCMP keys:
* "A STA shall use the temporal key as the CCMP key
* for MPDUs between the two communicating STAs."
*/
memcpy(tk_buf, ptk->tk, 16);
break;
case CRYPTO_CIPHER_TKIP:
/*
* 802.11-2016 12.8.1 Mapping PTK to TKIP keys:
* "A STA shall use bits 0-127 of the temporal key as its
* input to the TKIP Phase 1 and Phase 2 mixing functions.
*
* A STA shall use bits 128-191 of the temporal key as
* the michael key for MSDUs from the Authenticator's STA
* to the Supplicant's STA.
*
* A STA shall use bits 192-255 of the temporal key as
* the michael key for MSDUs from the Supplicant's STA
* to the Authenticator's STA."
*/
memcpy(tk_buf + NL80211_TKIP_DATA_OFFSET_ENCR_KEY, ptk->tk, 16);
memcpy(tk_buf + NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY,
ptk->tk + 16, 8);
memcpy(tk_buf + NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY,
ptk->tk + 24, 8);
break;
default:
l_error("Unexpected cipher: %x", cipher);
return;
}
msg = l_genl_msg_new_sized(NL80211_CMD_NEW_KEY, 128);
l_genl_msg_append_attr(msg, NL80211_ATTR_IFINDEX, 4, &ifindex);
l_genl_msg_append_attr(msg, NL80211_ATTR_MAC, 6, sta->addr);
l_genl_msg_append_attr(msg, NL80211_ATTR_KEY_IDX, 1, &key_id);
l_genl_msg_append_attr(msg, NL80211_ATTR_KEY_DATA,
crypto_cipher_key_len(cipher), tk_buf);
l_genl_msg_append_attr(msg, NL80211_ATTR_KEY_TYPE, 4, &key_type);
l_genl_msg_append_attr(msg, NL80211_ATTR_KEY_CIPHER, 4, &cipher);
if (!l_genl_family_send(nl80211, msg, ap_new_key_cb, NULL, NULL)) {
l_genl_msg_unref(msg);
l_error("Issuing NEW_KEY failed");
return;
}
}
static void ap_drop_rsna(struct ap_state *ap, struct sta_state *sta)
{
struct l_genl_msg *msg;
uint32_t ifindex = device_get_ifindex(ap->device);
struct nl80211_sta_flag_update flags = {
.mask = (1 << NL80211_STA_FLAG_AUTHORIZED) |
(1 << NL80211_STA_FLAG_MFP),
.set = 0,
};
uint8_t key_id = 0;
sta->rsna = false;
msg = l_genl_msg_new_sized(NL80211_CMD_SET_STATION, 128);
l_genl_msg_append_attr(msg, NL80211_ATTR_IFINDEX, 4, &ifindex);
l_genl_msg_append_attr(msg, NL80211_ATTR_MAC, 6, sta->addr);
l_genl_msg_append_attr(msg, NL80211_ATTR_STA_AID, 2, &sta->aid);
l_genl_msg_append_attr(msg, NL80211_ATTR_STA_FLAGS2, 8, &flags);
if (!l_genl_family_send(nl80211, msg, ap_set_sta_cb, NULL, NULL)) {
l_genl_msg_unref(msg);
l_error("Issuing SET_STATION failed");
}
msg = l_genl_msg_new_sized(NL80211_CMD_DEL_KEY, 64);
l_genl_msg_append_attr(msg, NL80211_ATTR_IFINDEX, 4, &ifindex);
l_genl_msg_append_attr(msg, NL80211_ATTR_KEY_IDX, 1, &key_id);
l_genl_msg_append_attr(msg, NL80211_ATTR_MAC, 6, sta->addr);
if (!l_genl_family_send(nl80211, msg, ap_del_key_cb, NULL, NULL)) {
l_genl_msg_unref(msg);
l_error("Issuing DEL_KEY failed");
}
}
#define CIPHER_SUITE_GROUP_NOT_ALLOWED 0x000fac07
static void ap_set_rsn_info(struct ap_state *ap, struct ie_rsn_info *rsn)
@ -308,6 +434,26 @@ static void ap_handle_ptk_2_of_4(struct sta_state *sta,
ap_send_ptk_3_of_4(sta->ap, sta);
}
/* 802.11-2016 Section 12.7.6.5 */
static void ap_handle_ptk_4_of_4(struct sta_state *sta,
const struct eapol_key *ek)
{
const struct crypto_ptk *ptk = (struct crypto_ptk *) sta->ptk;
l_debug("");
if (!eapol_verify_ptk_4_of_4(ek, false))
return;
if (L_BE64_TO_CPU(ek->key_replay_counter) != sta->key_replay_counter)
return;
if (!eapol_verify_mic(ptk->kck, ek))
return;
ap_new_rsna(sta->ap, sta);
}
static void ap_eapol_key_handle(struct sta_state *sta,
const struct eapol_frame *frame)
{
@ -326,6 +472,8 @@ static void ap_eapol_key_handle(struct sta_state *sta,
if (!sta->ptk_complete)
ap_handle_ptk_2_of_4(sta, ek);
else if (!sta->rsna)
ap_handle_ptk_4_of_4(sta, ek);
}
static void ap_eapol_rx(uint16_t proto, const uint8_t *from,
@ -506,6 +654,7 @@ static void ap_associate_sta(struct ap_state *ap, struct sta_state *sta)
uint16_t capability = l_get_le16(&sta->capability);
sta->associated = true;
sta->rsna = false;
sta->key_replay_counter = 0;
minr = l_uintset_find_min(sta->rates);
@ -550,6 +699,7 @@ static void ap_disassociate_sta(struct ap_state *ap, struct sta_state *sta)
uint8_t key_id = 0;
sta->associated = false;
sta->rsna = false;
msg = l_genl_msg_new_sized(NL80211_CMD_DEL_STATION, 64);
l_genl_msg_append_attr(msg, NL80211_ATTR_IFINDEX, 4, &ifindex);
@ -610,6 +760,10 @@ static void ap_success_assoc_resp_cb(struct l_genl_msg *msg, void *user_data)
return;
}
/* If we were in State 4, go to back to State 3 */
if (sta->rsna)
ap_drop_rsna(ap, sta);
/* If we were in State 2 also go to State 3 */
if (!sta->associated)
ap_associate_sta(ap, sta);
@ -801,6 +955,19 @@ static void ap_assoc_req_cb(struct netdev *netdev,
unsupported:
bad_frame:
/*
* TODO: MFP
*
* 802.11-2016 11.3.5.3 j)
* "if management frame protection is in use the state for the STA
* shall be left unchanged. and if management frame protection is
* not in use set to State 3 if it was in State 4."
*
* For now, we need to drop the RSNA.
*/
if (sta && sta->associated && sta->rsna)
ap_drop_rsna(ap, sta);
if (rates)
l_uintset_free(rates);