From 96590564d658cf344778e9c84bcd58d39764e11d Mon Sep 17 00:00:00 2001 From: Michael Braun Date: Sat, 24 Sep 2016 22:53:42 +0200 Subject: [PATCH] FT: Allow PMK-R0 and PMK-R1 for FT-PSK to be generated locally Station should be able to connect initially without ft_pmk_cache filled, so the target AP has the PSK available and thus the same information as the origin AP. Therefore neither caching nor communication between the APs with respect to PMK-R0 or PMK-R1 or VLANs is required if the target AP derives the required PMKs locally. This patch introduces the generation of the required PMKs locally for FT-PSK. Additionally, PMK-R0 is not stored (and thus pushed) for FT-PSK. So for FT-PSK networks, no configuration of inter-AP communication is needed anymore when using ft_psk_generate_local=1 configuration. The default behavior (ft_psk_generate_local=0) remains to use the pull/push protocol. Signed-off-by: Michael Braun --- hostapd/config_file.c | 2 + hostapd/hostapd.conf | 8 +++ src/ap/ap_config.h | 1 + src/ap/wpa_auth.h | 1 + src/ap/wpa_auth_ft.c | 116 +++++++++++++++++++++++++++++++++++++--- src/ap/wpa_auth_glue.c | 1 + src/common/defs.h | 5 ++ src/common/wpa_common.c | 2 + src/common/wpa_common.h | 2 + 9 files changed, 132 insertions(+), 6 deletions(-) diff --git a/hostapd/config_file.c b/hostapd/config_file.c index 5079f69e3..2d672825f 100644 --- a/hostapd/config_file.c +++ b/hostapd/config_file.c @@ -2559,6 +2559,8 @@ static int hostapd_config_fill(struct hostapd_config *conf, bss->pmk_r1_push = atoi(pos); } else if (os_strcmp(buf, "ft_over_ds") == 0) { bss->ft_over_ds = atoi(pos); + } else if (os_strcmp(buf, "ft_psk_generate_local") == 0) { + bss->ft_psk_generate_local = atoi(pos); #endif /* CONFIG_IEEE80211R */ #ifndef CONFIG_NO_CTRL_IFACE } else if (os_strcmp(buf, "ctrl_interface") == 0) { diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf index fa9a855a6..b5f5b1775 100644 --- a/hostapd/hostapd.conf +++ b/hostapd/hostapd.conf @@ -1326,6 +1326,14 @@ own_ip_addr=127.0.0.1 # 1 = FT-over-DS enabled (default) #ft_over_ds=1 +# Whether to generate FT response locally for PSK networks +# This avoids use of PMK-R1 push/pull from other APs with FT-PSK networks as +# the required information (PSK and other session data) is already locally +# available. +# 0 = disabled (default) +# 1 = enabled +#ft_psk_generate_local=0 + ##### Neighbor table ########################################################## # Maximum number of entries kept in AP table (either for neigbor table or for # detecting Overlapping Legacy BSS Condition). The oldest entry will be diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h index 8c8f7e286..f9b43064f 100644 --- a/src/ap/ap_config.h +++ b/src/ap/ap_config.h @@ -339,6 +339,7 @@ struct hostapd_bss_config { struct ft_remote_r1kh *r1kh_list; int pmk_r1_push; int ft_over_ds; + int ft_psk_generate_local; #endif /* CONFIG_IEEE80211R */ char *ctrl_interface; /* directory for UNIX domain sockets */ diff --git a/src/ap/wpa_auth.h b/src/ap/wpa_auth.h index 0de8d976e..571288411 100644 --- a/src/ap/wpa_auth.h +++ b/src/ap/wpa_auth.h @@ -170,6 +170,7 @@ struct wpa_auth_config { struct ft_remote_r1kh *r1kh_list; int pmk_r1_push; int ft_over_ds; + int ft_psk_generate_local; #endif /* CONFIG_IEEE80211R */ int disable_gtk; int ap_mlme; diff --git a/src/ap/wpa_auth_ft.c b/src/ap/wpa_auth_ft.c index 42242a54a..b3a7de979 100644 --- a/src/ap/wpa_auth_ft.c +++ b/src/ap/wpa_auth_ft.c @@ -51,6 +51,17 @@ static int wpa_ft_action_send(struct wpa_authenticator *wpa_auth, } +static const u8 * wpa_ft_get_psk(struct wpa_authenticator *wpa_auth, + const u8 *addr, const u8 *p2p_dev_addr, + const u8 *prev_psk) +{ + if (wpa_auth->cb.get_psk == NULL) + return NULL; + return wpa_auth->cb.get_psk(wpa_auth->cb.ctx, addr, p2p_dev_addr, + prev_psk); +} + + static struct wpa_state_machine * wpa_ft_add_sta(struct wpa_authenticator *wpa_auth, const u8 *sta_addr) { @@ -373,6 +384,7 @@ int wpa_auth_derive_ptk_ft(struct wpa_state_machine *sm, const u8 *pmk, const u8 *r1kh = sm->wpa_auth->conf.r1_key_holder; const u8 *ssid = sm->wpa_auth->conf.ssid; size_t ssid_len = sm->wpa_auth->conf.ssid_len; + int psk_local = sm->wpa_auth->conf.ft_psk_generate_local; if (sm->xxkey_len == 0) { wpa_printf(MSG_DEBUG, "FT: XXKey not available for key " @@ -384,16 +396,18 @@ int wpa_auth_derive_ptk_ft(struct wpa_state_machine *sm, const u8 *pmk, r0kh, r0kh_len, sm->addr, pmk_r0, pmk_r0_name); wpa_hexdump_key(MSG_DEBUG, "FT: PMK-R0", pmk_r0, PMK_LEN); wpa_hexdump(MSG_DEBUG, "FT: PMKR0Name", pmk_r0_name, WPA_PMK_NAME_LEN); - wpa_ft_store_pmk_r0(sm->wpa_auth, sm->addr, pmk_r0, pmk_r0_name, - sm->pairwise); + if (!psk_local || !wpa_key_mgmt_ft_psk(sm->wpa_key_mgmt)) + wpa_ft_store_pmk_r0(sm->wpa_auth, sm->addr, pmk_r0, pmk_r0_name, + sm->pairwise); wpa_derive_pmk_r1(pmk_r0, pmk_r0_name, r1kh, sm->addr, pmk_r1, sm->pmk_r1_name); wpa_hexdump_key(MSG_DEBUG, "FT: PMK-R1", pmk_r1, PMK_LEN); wpa_hexdump(MSG_DEBUG, "FT: PMKR1Name", sm->pmk_r1_name, WPA_PMK_NAME_LEN); - wpa_ft_store_pmk_r1(sm->wpa_auth, sm->addr, pmk_r1, sm->pmk_r1_name, - sm->pairwise); + if (!psk_local || !wpa_key_mgmt_ft_psk(sm->wpa_key_mgmt)) + wpa_ft_store_pmk_r1(sm->wpa_auth, sm->addr, pmk_r1, + sm->pmk_r1_name, sm->pairwise); return wpa_pmk_r1_to_ptk(pmk_r1, sm->SNonce, sm->ANonce, sm->addr, sm->wpa_auth->addr, sm->pmk_r1_name, @@ -795,6 +809,89 @@ void wpa_ft_install_ptk(struct wpa_state_machine *sm) } +/* Derive PMK-R1 from PSK, check all available PSK */ +static int wpa_ft_psk_pmk_r1(struct wpa_state_machine *sm, + const u8 *req_pmk_r1_name, + u8 *out_pmk_r1, int *out_pairwise) +{ + const u8 *pmk = NULL; + u8 pmk_r0[PMK_LEN], pmk_r0_name[WPA_PMK_NAME_LEN]; + u8 pmk_r1[PMK_LEN], pmk_r1_name[WPA_PMK_NAME_LEN]; + struct wpa_authenticator *wpa_auth = sm->wpa_auth; + const u8 *mdid = wpa_auth->conf.mobility_domain; + const u8 *r0kh = sm->r0kh_id; + size_t r0kh_len = sm->r0kh_id_len; + const u8 *r1kh = wpa_auth->conf.r1_key_holder; + const u8 *ssid = wpa_auth->conf.ssid; + size_t ssid_len = wpa_auth->conf.ssid_len; + int pairwise; + + pairwise = sm->pairwise; + + for (;;) { + pmk = wpa_ft_get_psk(wpa_auth, sm->addr, sm->p2p_dev_addr, + pmk); + if (pmk == NULL) + break; + + wpa_derive_pmk_r0(pmk, PMK_LEN, ssid, ssid_len, mdid, r0kh, + r0kh_len, sm->addr, pmk_r0, pmk_r0_name); + wpa_derive_pmk_r1(pmk_r0, pmk_r0_name, r1kh, sm->addr, + pmk_r1, pmk_r1_name); + + if (os_memcmp_const(pmk_r1_name, req_pmk_r1_name, + WPA_PMK_NAME_LEN) != 0) + continue; + + /* We found a PSK that matches the requested pmk_r1_name */ + wpa_printf(MSG_DEBUG, + "FT: Found PSK to generate PMK-R1 locally"); + os_memcpy(out_pmk_r1, pmk_r1, PMK_LEN); + if (out_pairwise) + *out_pairwise = pairwise; + return 0; + } + + wpa_printf(MSG_DEBUG, + "FT: Did not find PSK to generate PMK-R1 locally"); + return -1; +} + + +/* Detect the configuration the station asked for. + * Required to detect FT-PSK and pairwise cipher. + */ +static int wpa_ft_set_key_mgmt(struct wpa_state_machine *sm, + struct wpa_ft_ies *parse) +{ + int key_mgmt, ciphers; + + if (sm->wpa_key_mgmt) + return 0; + + key_mgmt = parse->key_mgmt & sm->wpa_auth->conf.wpa_key_mgmt; + if (!key_mgmt) { + wpa_printf(MSG_DEBUG, "FT: Invalid key mgmt (0x%x) from " + MACSTR, parse->key_mgmt, MAC2STR(sm->addr)); + return -1; + } + if (key_mgmt & WPA_KEY_MGMT_FT_IEEE8021X) + sm->wpa_key_mgmt = WPA_KEY_MGMT_FT_IEEE8021X; + else if (key_mgmt & WPA_KEY_MGMT_FT_PSK) + sm->wpa_key_mgmt = WPA_KEY_MGMT_FT_PSK; + ciphers = parse->pairwise_cipher & sm->wpa_auth->conf.rsn_pairwise; + if (!ciphers) { + wpa_printf(MSG_DEBUG, "FT: Invalid pairwise cipher (0x%x) from " + MACSTR, + parse->pairwise_cipher, MAC2STR(sm->addr)); + return -1; + } + sm->pairwise = wpa_pick_pairwise_cipher(ciphers, 0); + + return 0; +} + + static int wpa_ft_process_auth_req(struct wpa_state_machine *sm, const u8 *ies, size_t ies_len, u8 **resp_ies, size_t *resp_ies_len) @@ -856,6 +953,9 @@ static int wpa_ft_process_auth_req(struct wpa_state_machine *sm, return WLAN_STATUS_INVALID_PMKID; } + if (wpa_ft_set_key_mgmt(sm, &parse) < 0) + return WLAN_STATUS_UNSPECIFIED_FAILURE; + wpa_hexdump(MSG_DEBUG, "FT: Requested PMKR0Name", parse.rsn_pmkid, WPA_PMK_NAME_LEN); wpa_derive_pmk_r1_name(parse.rsn_pmkid, @@ -864,8 +964,12 @@ static int wpa_ft_process_auth_req(struct wpa_state_machine *sm, wpa_hexdump(MSG_DEBUG, "FT: Derived requested PMKR1Name", pmk_r1_name, WPA_PMK_NAME_LEN); - if (wpa_ft_fetch_pmk_r1(sm->wpa_auth, sm->addr, pmk_r1_name, pmk_r1, - &pairwise) < 0) { + if (conf->ft_psk_generate_local && + wpa_key_mgmt_ft_psk(sm->wpa_key_mgmt)) { + if (wpa_ft_psk_pmk_r1(sm, pmk_r1_name, pmk_r1, &pairwise) < 0) + return WLAN_STATUS_INVALID_PMKID; + } else if (wpa_ft_fetch_pmk_r1(sm->wpa_auth, sm->addr, pmk_r1_name, + pmk_r1, &pairwise) < 0) { if (wpa_ft_pull_pmk_r1(sm, ies, ies_len, parse.rsn_pmkid) < 0) { wpa_printf(MSG_DEBUG, "FT: Did not have matching " "PMK-R1 and unknown R0KH-ID"); diff --git a/src/ap/wpa_auth_glue.c b/src/ap/wpa_auth_glue.c index 21424147e..2a5a940ec 100644 --- a/src/ap/wpa_auth_glue.c +++ b/src/ap/wpa_auth_glue.c @@ -73,6 +73,7 @@ static void hostapd_wpa_auth_conf(struct hostapd_bss_config *conf, wconf->r1kh_list = conf->r1kh_list; wconf->pmk_r1_push = conf->pmk_r1_push; wconf->ft_over_ds = conf->ft_over_ds; + wconf->ft_psk_generate_local = conf->ft_psk_generate_local; #endif /* CONFIG_IEEE80211R */ #ifdef CONFIG_HS20 wconf->disable_gtk = conf->disable_dgaf; diff --git a/src/common/defs.h b/src/common/defs.h index 4f5679459..4ab6c3f8c 100644 --- a/src/common/defs.h +++ b/src/common/defs.h @@ -79,6 +79,11 @@ static inline int wpa_key_mgmt_ft(int akm) WPA_KEY_MGMT_FT_SAE)); } +static inline int wpa_key_mgmt_ft_psk(int akm) +{ + return !!(akm & WPA_KEY_MGMT_FT_PSK); +} + static inline int wpa_key_mgmt_sae(int akm) { return !!(akm & (WPA_KEY_MGMT_SAE | diff --git a/src/common/wpa_common.c b/src/common/wpa_common.c index 299b8bbee..5477a98e1 100644 --- a/src/common/wpa_common.c +++ b/src/common/wpa_common.c @@ -376,6 +376,8 @@ int wpa_ft_parse_ies(const u8 *ies, size_t ies_len, } if (data.num_pmkid == 1 && data.pmkid) parse->rsn_pmkid = data.pmkid; + parse->key_mgmt = data.key_mgmt; + parse->pairwise_cipher = data.pairwise_cipher; break; case WLAN_EID_MOBILITY_DOMAIN: if (len < sizeof(struct rsn_mdie)) diff --git a/src/common/wpa_common.h b/src/common/wpa_common.h index af1d0f0c6..6d446e8e5 100644 --- a/src/common/wpa_common.h +++ b/src/common/wpa_common.h @@ -430,6 +430,8 @@ struct wpa_ft_ies { size_t igtk_len; const u8 *ric; size_t ric_len; + int key_mgmt; + int pairwise_cipher; }; int wpa_ft_parse_ies(const u8 *ies, size_t ies_len, struct wpa_ft_ies *parse);