diff --git a/hostapd/config_file.c b/hostapd/config_file.c index f77651a7b..6dde59a5a 100644 --- a/hostapd/config_file.c +++ b/hostapd/config_file.c @@ -2874,6 +2874,15 @@ static int hostapd_config_fill(struct hostapd_config *conf, bss->wpa_gmk_rekey = atoi(pos); } else if (os_strcmp(buf, "wpa_ptk_rekey") == 0) { bss->wpa_ptk_rekey = atoi(pos); + } else if (os_strcmp(buf, "wpa_deny_ptk0_rekey") == 0) { + bss->wpa_deny_ptk0_rekey = atoi(pos); + if (bss->wpa_deny_ptk0_rekey < 0 || + bss->wpa_deny_ptk0_rekey > 2) { + wpa_printf(MSG_ERROR, + "Line %d: Invalid wpa_deny_ptk0_rekey=%d; allowed range 0..2", + line, bss->wpa_deny_ptk0_rekey); + return 1; + } } else if (os_strcmp(buf, "wpa_group_update_count") == 0) { char *endp; unsigned long val = strtoul(pos, &endp, 0); diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf index 0433fed8a..0f8461d49 100644 --- a/hostapd/hostapd.conf +++ b/hostapd/hostapd.conf @@ -904,6 +904,8 @@ eapol_key_index_workaround=0 # EAP reauthentication period in seconds (default: 3600 seconds; 0 = disable # reauthentication). +# Note: Reauthentications may enforce a disconnection, check the related +# parameter wpa_deny_ptk0_rekey for details. #eap_reauth_period=3600 # Use PAE group address (01:80:c2:00:00:03) instead of individual target @@ -1608,8 +1610,40 @@ own_ip_addr=127.0.0.1 # Maximum lifetime for PTK in seconds. This can be used to enforce rekeying of # PTK to mitigate some attacks against TKIP deficiencies. +# Warning: PTK rekeying is buggy with many drivers/devices and with such +# devices, the only secure method to rekey the PTK without Extended Key ID +# support requires a disconnection. Check the related parameter +# wpa_deny_ptk0_rekey for details. #wpa_ptk_rekey=600 +# Workaround for PTK rekey issues +# +# Rekeying the PTK without using "Extended Key ID for Individually Addressed +# Frames" (two different Key ID values for pairwise keys) can, depending on the +# used cards/drivers, impact the security and stability of connections. Both +# ends can accidentally trick one end to drop all packets send by it until the +# connection is torn down or rekeyed again. Additionally, some drivers may +# skip/break the encryption for the time window the key is updated (normally a +# few milliseconds). +# +# To avoid such issues, hostapd can now replace all PTK rekeys using only keyid +# 0 (PTK0 rekeys) with disconnection that forces the remote stations to +# reconnect instead. +# +# EAP reauthentication depends on replacing the PTK and is therefore just +# another way to rekey the PTK and is affected by this parameter, too. +# +# "Extended Key ID for Individually Addressed Frames" is avoiding the issues +# using two separate keys and this parameter will be ignored when using it +# (i.e., PTK rekeying is allowed regardless of this parameter value). +# +# Available options: +# 0 = always rekey when configured/instructed (default) +# 1 = only rekey when the local driver is explicitly indicating it can perform +# this operation without issues +# 2 = never allow PTK0 rekeys +#wpa_deny_ptk0_rekey=0 + # The number of times EAPOL-Key Message 1/4 and Message 3/4 in the RSN 4-Way # Handshake are retried per 4-Way Handshake attempt. # (dot11RSNAConfigPairwiseUpdateCount) diff --git a/src/ap/ap_config.c b/src/ap/ap_config.c index b63c64bb6..fddc8ca44 100644 --- a/src/ap/ap_config.c +++ b/src/ap/ap_config.c @@ -64,6 +64,7 @@ void hostapd_config_defaults_bss(struct hostapd_bss_config *bss) bss->wpa_group_rekey = 600; bss->wpa_gmk_rekey = 86400; + bss->wpa_deny_ptk0_rekey = PTK0_REKEY_ALLOW_ALWAYS; bss->wpa_group_update_count = 4; bss->wpa_pairwise_update_count = 4; bss->wpa_disable_eapol_key_retries = diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h index ca9ae14cd..b6e11f25f 100644 --- a/src/ap/ap_config.h +++ b/src/ap/ap_config.h @@ -370,6 +370,7 @@ struct hostapd_bss_config { int wpa_strict_rekey; int wpa_gmk_rekey; int wpa_ptk_rekey; + enum ptk0_rekey_handling wpa_deny_ptk0_rekey; u32 wpa_group_update_count; u32 wpa_pairwise_update_count; int wpa_disable_eapol_key_retries; diff --git a/src/ap/wpa_auth.c b/src/ap/wpa_auth.c index 1f835d80a..e67c34498 100644 --- a/src/ap/wpa_auth.c +++ b/src/ap/wpa_auth.c @@ -781,8 +781,18 @@ static void wpa_request_new_ptk(struct wpa_state_machine *sm) if (sm == NULL) return; - sm->PTKRequest = TRUE; - sm->PTK_valid = 0; + if (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 to reconnect */ + sm->disconnect_reason = + WLAN_REASON_CLASS3_FRAME_FROM_NONASSOC_STA; + } else { + sm->PTKRequest = TRUE; + sm->PTK_valid = 0; + } } @@ -1802,6 +1812,15 @@ 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) { + wpa_printf(MSG_INFO, + "WPA: PTK0 rekey not allowed, disconnect " + MACSTR, MAC2STR(sm->addr)); + sm->Disconnect = TRUE; + /* Try to encourage the STA reconnect */ + sm->disconnect_reason = + WLAN_REASON_CLASS3_FRAME_FROM_NONASSOC_STA; + break; } if (sm->GUpdateStationKeys) { /* diff --git a/src/ap/wpa_auth.h b/src/ap/wpa_auth.h index 93e0c745d..1f7ba4899 100644 --- a/src/ap/wpa_auth.h +++ b/src/ap/wpa_auth.h @@ -176,6 +176,7 @@ struct wpa_auth_config { int wpa_strict_rekey; int wpa_gmk_rekey; int wpa_ptk_rekey; + int wpa_deny_ptk0_rekey; u32 wpa_group_update_count; u32 wpa_pairwise_update_count; int wpa_disable_eapol_key_retries; diff --git a/src/ap/wpa_auth_glue.c b/src/ap/wpa_auth_glue.c index 7dc4c8e6b..82e82a7d2 100644 --- a/src/ap/wpa_auth_glue.c +++ b/src/ap/wpa_auth_glue.c @@ -1381,6 +1381,16 @@ int hostapd_setup_wpa(struct hostapd_data *hapd) _conf.tx_status = 1; if (hapd->iface->drv_flags & WPA_DRIVER_FLAGS_AP_MLME) _conf.ap_mlme = 1; + + if (!(hapd->iface->drv_flags & WPA_DRIVER_FLAGS_WIRED) && + (hapd->conf->wpa_deny_ptk0_rekey == PTK0_REKEY_ALLOW_NEVER || + (hapd->conf->wpa_deny_ptk0_rekey == PTK0_REKEY_ALLOW_LOCAL_OK && + !(hapd->iface->drv_flags & WPA_DRIVER_FLAGS_SAFE_PTK0_REKEYS)))) { + wpa_msg(hapd->msg_ctx, MSG_INFO, + "Disable PTK0 rekey support - replaced with disconnect"); + _conf.wpa_deny_ptk0_rekey = 1; + } + hapd->wpa_auth = wpa_init(hapd->own_addr, &_conf, &cb, hapd); if (hapd->wpa_auth == NULL) { wpa_printf(MSG_ERROR, "WPA initialization failed."); diff --git a/src/common/defs.h b/src/common/defs.h index 5e22278e6..1e21ec2de 100644 --- a/src/common/defs.h +++ b/src/common/defs.h @@ -445,4 +445,10 @@ enum key_flag { KEY_FLAG_MODIFY, }; +enum ptk0_rekey_handling { + PTK0_REKEY_ALLOW_ALWAYS, + PTK0_REKEY_ALLOW_LOCAL_OK, + PTK0_REKEY_ALLOW_NEVER +}; + #endif /* DEFS_H */