Re: [PATCH 1/6] FT: Allow roaming between APs if IDs match MAC

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On Mi, 2016-09-21 at 10:32 +0200, Michael Braun wrote:
> do I undertand correctly that this change also requires
> nas_identifier to be the BSSID?

That is correct. The code assumes that the nas_identifier matches the
BSSID to be able to send requests without having prior knowledge about
other APs in the network.

Benjamin


> Am 19.09.2016 17:47, schrieb Benjamin Berg:
> > 
> > From: Benjamin Berg <benjamin.berg@xxxxxxxxxxxxx>
> > 
> > This patch adds a new option to set a static key for the
> > communication
> > between the APs during 802.11r roaming. For this to work hostapd
> > has to assume that both the nas_identifier and R1KH identifier
> > match
> > the MAC/BSSID of the hostapd instance.
> > 
> > The advantage is that all APs can share a common configuration and 
> > roaming
> > works throughout the network without each AP having a list of all
> > other
> > APs and a key for them. It is assumed that all APs can communicate
> > on a
> > common layer two network.
> > 
> > Signed-off-by: Benjamin Berg <benjamin.berg@xxxxxxxxxxxxx>
> > ---
> >  hostapd/config_file.c  |   9 +++
> >  src/ap/ap_config.h     |   2 +
> >  src/ap/wpa_auth.h      |   2 +
> >  src/ap/wpa_auth_ft.c   | 173 
> > +++++++++++++++++++++++++++++++++++++------------
> >  src/ap/wpa_auth_glue.c |   2 +
> >  5 files changed, 146 insertions(+), 42 deletions(-)
> > 
> > diff --git a/hostapd/config_file.c b/hostapd/config_file.c
> > index 5079f69..a43fa2f 100644
> > --- a/hostapd/config_file.c
> > +++ b/hostapd/config_file.c
> > @@ -2555,6 +2555,15 @@ static int hostapd_config_fill(struct
> > hostapd_config *conf,
> >  				   line, pos);
> >  			return 1;
> >  		}
> > +	} else if (os_strcmp(buf, "ft_remote_key") == 0) {
> > +
> > +		bss->ft_remote_trust_khid = 1;
> > +
> > +		if (hexstr2bin(pos, bss->ft_remote_key,
> > sizeof(bss->ft_remote_key))) 
> > {
> > +			wpa_printf(MSG_ERROR, "Invalid FT
> > communication key: '%s'", pos);
> > +			return 1;
> > +		}
> > +
> >  	} else if (os_strcmp(buf, "pmk_r1_push") == 0) {
> >  		bss->pmk_r1_push = atoi(pos);
> >  	} else if (os_strcmp(buf, "ft_over_ds") == 0) {
> > diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h
> > index 8c8f7e2..5896f90 100644
> > --- a/src/ap/ap_config.h
> > +++ b/src/ap/ap_config.h
> > @@ -337,6 +337,8 @@ struct hostapd_bss_config {
> >  	u32 reassociation_deadline;
> >  	struct ft_remote_r0kh *r0kh_list;
> >  	struct ft_remote_r1kh *r1kh_list;
> > +	int ft_remote_trust_khid;
> > +	u8 ft_remote_key[16];
> >  	int pmk_r1_push;
> >  	int ft_over_ds;
> >  #endif /* CONFIG_IEEE80211R */
> > diff --git a/src/ap/wpa_auth.h b/src/ap/wpa_auth.h
> > index 0de8d97..cd70912 100644
> > --- a/src/ap/wpa_auth.h
> > +++ b/src/ap/wpa_auth.h
> > @@ -168,6 +168,8 @@ struct wpa_auth_config {
> >  	u32 reassociation_deadline;
> >  	struct ft_remote_r0kh *r0kh_list;
> >  	struct ft_remote_r1kh *r1kh_list;
> > +	int ft_remote_trust_khid;
> > +	u8 ft_remote_key[16];
> >  	int pmk_r1_push;
> >  	int ft_over_ds;
> >  #endif /* CONFIG_IEEE80211R */
> > diff --git a/src/ap/wpa_auth_ft.c b/src/ap/wpa_auth_ft.c
> > index 42242a5..a6e277d 100644
> > --- a/src/ap/wpa_auth_ft.c
> > +++ b/src/ap/wpa_auth_ft.c
> > @@ -300,30 +300,125 @@ static int wpa_ft_fetch_pmk_r1(struct
> > wpa_authenticator *wpa_auth,
> >  	return -1;
> >  }
> > 
> > -
> > -static int wpa_ft_pull_pmk_r1(struct wpa_state_machine *sm,
> > -			      const u8 *ies, size_t ies_len,
> > -			      const u8 *pmk_r0_name)
> > +static int wpa_ft_r0kh_find_by_id(struct wpa_authenticator
> > *wpa_auth,
> > +				  const u8 *r0kh_id,
> > +				  int r0kh_id_len,
> > +				  u8 *addr,
> > +				  u8 *key)
> >  {
> >  	struct ft_remote_r0kh *r0kh;
> > -	struct ft_r0kh_r1kh_pull_frame frame, f;
> > 
> > -	r0kh = sm->wpa_auth->conf.r0kh_list;
> > +	/* First try to lookup in list. */
> > +	r0kh = wpa_auth->conf.r0kh_list;
> >  	while (r0kh) {
> > -		if (r0kh->id_len == sm->r0kh_id_len &&
> > -		    os_memcmp_const(r0kh->id, sm->r0kh_id, sm-
> > >r0kh_id_len) ==
> > +		if (r0kh->id_len == r0kh_id_len &&
> > +		    os_memcmp_const(r0kh->id, r0kh_id,
> > r0kh_id_len) ==
> >  		    0)
> >  			break;
> >  		r0kh = r0kh->next;
> >  	}
> >  	if (r0kh == NULL) {
> > -		wpa_hexdump(MSG_DEBUG, "FT: Did not find R0KH-ID",
> > +		/* If we trust the KHID to be a MAC, then use this
> > instead.
> > +		 **/
> > +		if (wpa_auth->conf.ft_remote_trust_khid &&
> > r0kh_id_len == (3*6-1)) {
> > +			if (hwaddr_aton((char*) r0kh_id, addr)) {
> > +				return -1;
> > +			}
> > +			os_memcpy(key, wpa_auth-
> > >conf.ft_remote_key,
> > +				  sizeof(wpa_auth-
> > >conf.ft_remote_key));
> > +		} else {
> > +			return -1;
> > +		}
> > +	} else {
> > +		os_memcpy(key, r0kh->key,
> > +			  sizeof(r0kh->key));
> > +		os_memcpy(addr, r0kh->addr,
> > +			  ETH_ALEN);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int wpa_ft_r0kh_find_by_addr(struct wpa_authenticator 
> > *wpa_auth,
> > +				   const u8 *r0kh_addr,
> > +				   u8 *key)
> > +{
> > +	struct ft_remote_r0kh *r0kh;
> > +
> > +	/* First try to lookup in list. */
> > +	r0kh = wpa_auth->conf.r0kh_list;
> > +	while (r0kh) {
> > +		if (os_memcmp_const(r0kh->addr, r0kh_addr,
> > ETH_ALEN) == 0)
> > +			break;
> > +		r0kh = r0kh->next;
> > +	}
> > +	if (r0kh == NULL) {
> > +		/* If we trust the KHID to be a MAC, then use this
> > instead.
> > +		 **/
> > +		if (wpa_auth->conf.ft_remote_trust_khid) {
> > +			os_memcpy(key, wpa_auth-
> > >conf.ft_remote_key,
> > +				  sizeof(wpa_auth-
> > >conf.ft_remote_key));
> > +		} else {
> > +			return -1;
> > +		}
> > +	} else {
> > +		os_memcpy(key, r0kh->key,
> > +			  sizeof(r0kh->key));
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int wpa_ft_r1kh_find_by_addr(struct wpa_authenticator 
> > *wpa_auth,
> > +			     const u8 *src_addr,
> > +			     u8 *id,
> > +			     u8 *key)
> > +{
> > +	struct ft_remote_r1kh *r1kh;
> > +
> > +	/* First try to lookup in list. */
> > +	r1kh = wpa_auth->conf.r1kh_list;
> > +	while (r1kh) {
> > +		if (os_memcmp(r1kh->addr, src_addr, ETH_ALEN) ==
> > 0)
> > +			break;
> > +		r1kh = r1kh->next;
> > +	}
> > +	if (r1kh == NULL) {
> > +		/* If we trust the KHID to be a MAC, then use this
> > instead.
> > +		 **/
> > +		if (wpa_auth->conf.ft_remote_trust_khid) {
> > +			os_memcpy(id, src_addr, ETH_ALEN);
> > +			os_memcpy(key, wpa_auth-
> > >conf.ft_remote_key,
> > +				  sizeof(wpa_auth-
> > >conf.ft_remote_key));
> > +		} else {
> > +			return -1;
> > +		}
> > +	} else {
> > +		os_memcpy(id, r1kh->id, ETH_ALEN);
> > +		os_memcpy(key, r1kh->key,
> > +			  sizeof(r1kh->key));
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int wpa_ft_pull_pmk_r1(struct wpa_state_machine *sm,
> > +			      const u8 *ies, size_t ies_len,
> > +			      const u8 *pmk_r0_name)
> > +{
> > +	macaddr r0kh_addr;
> > +	u8 r0kh_key[16];
> > +	struct ft_r0kh_r1kh_pull_frame frame, f;
> > +
> > +	if (wpa_ft_r0kh_find_by_id(sm->wpa_auth, sm->r0kh_id, 
> > sm->r0kh_id_len,
> > +				    r0kh_addr, r0kh_key)) {
> > +		wpa_hexdump(MSG_DEBUG, "FT: Cannot pull PMK-R1 for
> > R0KH",
> >  			    sm->r0kh_id, sm->r0kh_id_len);
> >  		return -1;
> >  	}
> > 
> >  	wpa_printf(MSG_DEBUG, "FT: Send PMK-R1 pull request to
> > remote R0KH "
> > -		   "address " MACSTR, MAC2STR(r0kh->addr));
> > +		   "address " MACSTR, MAC2STR(r0kh_addr));
> > 
> >  	os_memset(&frame, 0, sizeof(frame));
> >  	frame.frame_type = RSN_REMOTE_FRAME_TYPE_FT_RRB;
> > @@ -345,7 +440,7 @@ static int wpa_ft_pull_pmk_r1(struct 
> > wpa_state_machine *sm,
> >  	os_memcpy(f.s1kh_id, sm->addr, ETH_ALEN);
> >  	os_memset(f.pad, 0, sizeof(f.pad));
> > 
> > -	if (aes_wrap(r0kh->key, sizeof(r0kh->key),
> > +	if (aes_wrap(r0kh_key, sizeof(r0kh_key),
> >  		     (FT_R0KH_R1KH_PULL_DATA_LEN + 7) / 8,
> >  		     f.nonce, frame.nonce) < 0)
> >  		return -1;
> > @@ -355,7 +450,7 @@ static int wpa_ft_pull_pmk_r1(struct 
> > wpa_state_machine *sm,
> >  	if (sm->ft_pending_req_ies == NULL)
> >  		return -1;
> > 
> > -	wpa_ft_rrb_send(sm->wpa_auth, r0kh->addr, (u8 *) &frame, 
> > sizeof(frame));
> > +	wpa_ft_rrb_send(sm->wpa_auth, r0kh_addr, (u8 *) &frame, 
> > sizeof(frame));
> > 
> >  	return 0;
> >  }
> > @@ -1313,7 +1408,8 @@ static int wpa_ft_rrb_rx_pull(struct
> > wpa_authenticator *wpa_auth,
> >  	struct ft_r0kh_r1kh_pull_frame f;
> >  	const u8 *crypt;
> >  	u8 *plain;
> > -	struct ft_remote_r1kh *r1kh;
> > +	u8 r1kh_id[FT_R1KH_ID_LEN];
> > +	u8 r1kh_key[16];
> >  	struct ft_r0kh_r1kh_resp_frame resp, r;
> >  	u8 pmk_r0[PMK_LEN];
> >  	int pairwise;
> > @@ -1323,13 +1419,8 @@ static int wpa_ft_rrb_rx_pull(struct
> > wpa_authenticator *wpa_auth,
> >  	if (data_len < sizeof(f))
> >  		return -1;
> > 
> > -	r1kh = wpa_auth->conf.r1kh_list;
> > -	while (r1kh) {
> > -		if (os_memcmp(r1kh->addr, src_addr, ETH_ALEN) ==
> > 0)
> > -			break;
> > -		r1kh = r1kh->next;
> > -	}
> > -	if (r1kh == NULL) {
> > +
> > +	if (wpa_ft_r1kh_find_by_addr(wpa_auth, src_addr, r1kh_id,
> > r1kh_key) 
> > != 0) {
> >  		wpa_printf(MSG_DEBUG, "FT: No matching R1KH
> > address found for "
> >  			   "PMK-R1 pull source address " MACSTR,
> >  			   MAC2STR(src_addr));
> > @@ -1341,7 +1432,7 @@ static int wpa_ft_rrb_rx_pull(struct
> > wpa_authenticator *wpa_auth,
> >  	plain = ((u8 *) &f) + offsetof(struct
> > ft_r0kh_r1kh_pull_frame, 
> > nonce);
> >  	/* aes_unwrap() does not support inplace decryption, so
> > use a 
> > temporary
> >  	 * buffer for the data. */
> > -	if (aes_unwrap(r1kh->key, sizeof(r1kh->key),
> > +	if (aes_unwrap(r1kh_key, sizeof(r1kh_key),
> >  		       (FT_R0KH_R1KH_PULL_DATA_LEN + 7) / 8,
> >  		       crypt, plain) < 0) {
> >  		wpa_printf(MSG_DEBUG, "FT: Failed to decrypt PMK-
> > R1 pull "
> > @@ -1349,6 +1440,16 @@ static int wpa_ft_rrb_rx_pull(struct
> > wpa_authenticator *wpa_auth,
> >  		return -1;
> >  	}
> > 
> > +	/* Ensure that R1KH-ID matches the expected value. */
> > +	if (os_memcmp(r1kh_id, f.r1kh_id, FT_R1KH_ID_LEN) != 0) {
> > +		wpa_printf(MSG_ERROR, "FT: PMK-R1 pull included
> > R1KH_ID "
> > +			   "(" MACSTR ") that did not match the
> > packet "
> > +			   "senders ID (" MACSTR ", MAC " MACSTR
> > ")",
> > +			   MAC2STR(f.r1kh_id), MAC2STR(r1kh_id),
> > +			   MAC2STR(src_addr));
> > +		return -1;
> > +	}
> > +
> >  	wpa_hexdump(MSG_DEBUG, "FT: PMK-R1 pull - nonce",
> >  		    f.nonce, sizeof(f.nonce));
> >  	wpa_hexdump(MSG_DEBUG, "FT: PMK-R1 pull - PMKR0Name",
> > @@ -1382,7 +1483,7 @@ static int wpa_ft_rrb_rx_pull(struct
> > wpa_authenticator *wpa_auth,
> >  	r.pairwise = host_to_le16(pairwise);
> >  	os_memset(r.pad, 0, sizeof(r.pad));
> > 
> > -	if (aes_wrap(r1kh->key, sizeof(r1kh->key),
> > +	if (aes_wrap(r1kh_key, sizeof(r1kh_key),
> >  		     (FT_R0KH_R1KH_RESP_DATA_LEN + 7) / 8,
> >  		     r.nonce, resp.nonce) < 0) {
> >  		os_memset(pmk_r0, 0, PMK_LEN);
> > @@ -1449,7 +1550,7 @@ static int wpa_ft_rrb_rx_resp(struct
> > wpa_authenticator *wpa_auth,
> >  	struct ft_r0kh_r1kh_resp_frame f;
> >  	const u8 *crypt;
> >  	u8 *plain;
> > -	struct ft_remote_r0kh *r0kh;
> > +	u8 r0kh_key[16];
> >  	int pairwise, res;
> > 
> >  	wpa_printf(MSG_DEBUG, "FT: Received PMK-R1 pull
> > response");
> > @@ -1457,14 +1558,8 @@ static int wpa_ft_rrb_rx_resp(struct
> > wpa_authenticator *wpa_auth,
> >  	if (data_len < sizeof(f))
> >  		return -1;
> > 
> > -	r0kh = wpa_auth->conf.r0kh_list;
> > -	while (r0kh) {
> > -		if (os_memcmp(r0kh->addr, src_addr, ETH_ALEN) ==
> > 0)
> > -			break;
> > -		r0kh = r0kh->next;
> > -	}
> > -	if (r0kh == NULL) {
> > -		wpa_printf(MSG_DEBUG, "FT: No matching R0KH
> > address found for "
> > +	if (wpa_ft_r0kh_find_by_addr(wpa_auth, src_addr,
> > r0kh_key)) {
> > +		wpa_printf(MSG_DEBUG, "FT: No R0KH address found
> > for "
> >  			   "PMK-R0 pull response source address "
> > MACSTR,
> >  			   MAC2STR(src_addr));
> >  		return -1;
> > @@ -1475,7 +1570,7 @@ static int wpa_ft_rrb_rx_resp(struct
> > wpa_authenticator *wpa_auth,
> >  	plain = ((u8 *) &f) + offsetof(struct
> > ft_r0kh_r1kh_resp_frame, 
> > nonce);
> >  	/* aes_unwrap() does not support inplace decryption, so
> > use a 
> > temporary
> >  	 * buffer for the data. */
> > -	if (aes_unwrap(r0kh->key, sizeof(r0kh->key),
> > +	if (aes_unwrap(r0kh_key, sizeof(r0kh_key),
> >  		       (FT_R0KH_R1KH_RESP_DATA_LEN + 7) / 8,
> >  		       crypt, plain) < 0) {
> >  		wpa_printf(MSG_DEBUG, "FT: Failed to decrypt PMK-
> > R1 pull "
> > @@ -1518,7 +1613,7 @@ static int wpa_ft_rrb_rx_push(struct
> > wpa_authenticator *wpa_auth,
> >  	struct ft_r0kh_r1kh_push_frame f;
> >  	const u8 *crypt;
> >  	u8 *plain;
> > -	struct ft_remote_r0kh *r0kh;
> > +	u8 r0kh_key[16];
> >  	struct os_time now;
> >  	os_time_t tsend;
> >  	int pairwise;
> > @@ -1528,14 +1623,8 @@ static int wpa_ft_rrb_rx_push(struct
> > wpa_authenticator *wpa_auth,
> >  	if (data_len < sizeof(f))
> >  		return -1;
> > 
> > -	r0kh = wpa_auth->conf.r0kh_list;
> > -	while (r0kh) {
> > -		if (os_memcmp(r0kh->addr, src_addr, ETH_ALEN) ==
> > 0)
> > -			break;
> > -		r0kh = r0kh->next;
> > -	}
> > -	if (r0kh == NULL) {
> > -		wpa_printf(MSG_DEBUG, "FT: No matching R0KH
> > address found for "
> > +	if (wpa_ft_r0kh_find_by_addr(wpa_auth, src_addr,
> > r0kh_key)) {
> > +		wpa_printf(MSG_DEBUG, "FT: No R0KH address found
> > for "
> >  			   "PMK-R0 push source address " MACSTR,
> >  			   MAC2STR(src_addr));
> >  		return -1;
> > @@ -1547,7 +1636,7 @@ static int wpa_ft_rrb_rx_push(struct
> > wpa_authenticator *wpa_auth,
> >  				       timestamp);
> >  	/* aes_unwrap() does not support inplace decryption, so
> > use a 
> > temporary
> >  	 * buffer for the data. */
> > -	if (aes_unwrap(r0kh->key, sizeof(r0kh->key),
> > +	if (aes_unwrap(r0kh_key, sizeof(r0kh_key),
> >  		       (FT_R0KH_R1KH_PUSH_DATA_LEN + 7) / 8,
> >  		       crypt, plain) < 0) {
> >  		wpa_printf(MSG_DEBUG, "FT: Failed to decrypt PMK-
> > R1 push from "
> > diff --git a/src/ap/wpa_auth_glue.c b/src/ap/wpa_auth_glue.c
> > index 2142414..90e39a4 100644
> > --- a/src/ap/wpa_auth_glue.c
> > +++ b/src/ap/wpa_auth_glue.c
> > @@ -71,6 +71,8 @@ static void hostapd_wpa_auth_conf(struct
> > hostapd_bss_config *conf,
> >  	wconf->reassociation_deadline = conf-
> > >reassociation_deadline;
> >  	wconf->r0kh_list = conf->r0kh_list;
> >  	wconf->r1kh_list = conf->r1kh_list;
> > +	wconf->ft_remote_trust_khid = conf->ft_remote_trust_khid;
> > +	os_memcpy(wconf->ft_remote_key, conf->ft_remote_key,
> > sizeof(wconf->ft_remote_key));
> >  	wconf->pmk_r1_push = conf->pmk_r1_push;
> >  	wconf->ft_over_ds = conf->ft_over_ds;
> >  #endif /* CONFIG_IEEE80211R */
> 
> _______________________________________________
> Hostap mailing list
> Hostap@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/hostap
> 

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