[PATCH 09/12] MLD STA: Add support for validating MLO KDEs for 4WHS EAPOL frames

[Peer, Ilan]

Hi,

> -----Original Message-----
> From: Hostap <hostap-bounces at lists.infradead.org> On Behalf Of
> Veerendranath Jakkam
> Sent: Thursday, August 25, 2022 08:53
> To: hostap at lists.infradead.org
> Cc: quic_vjakkam at quicinc.com
> Subject: [PATCH 09/12] MLD STA: Add support for validating MLO KDEs for
> 4WHS EAPOL frames
> 
> Validate new KDEs defined for MLO connection in EAPOL 1/4 and 3/4 and
> reject the Four-Way handshake frames if any of the new KDE data is not
> matching expected key data.
> 
> Signed-off-by: Veerendranath Jakkam <quic_vjakkam at quicinc.com>
> ---
>  src/rsn_supp/wpa.c | 147
> +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 147 insertions(+)
> 
> diff --git a/src/rsn_supp/wpa.c b/src/rsn_supp/wpa.c index
> 96adc4817..9a4e0ebee 100644
> --- a/src/rsn_supp/wpa.c
> +++ b/src/rsn_supp/wpa.c
> @@ -785,6 +785,14 @@ static void wpa_supplicant_process_1_of_4(struct
> wpa_sm *sm,
>  		}
>  	}
> 
> +	if (sm->valid_links &&
> +	    (!ie.mac_addr || ie.mac_addr_len < ETH_ALEN ||
> +	     os_memcmp(ie.mac_addr, sm->ap_mld_addr, ETH_ALEN))) {
> +		wpa_printf(MSG_INFO,
> +			  "RSN MLO: Discard EAPOL-Key msg 1/4 with invalid
> MAC address KDE");
> +		return;
> +	}
> +

The MAC address validation can also be moved to a function.

>  	res = wpa_supplicant_get_pmk(sm, src_addr, ie.pmkid);
>  	if (res == -2) {
>  		wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG, "RSN: Do not
> reply to "
> @@ -2092,6 +2100,131 @@ int wpa_supplicant_send_4_of_4(struct wpa_sm
> *sm, const unsigned char *dst,  }
> 
> 
> +static int wpa_supplicant_validate_link_kde(struct wpa_sm *sm,
> +					    u8 link_id,
> +					    const u8 *link_kde,
> +					    size_t link_kde_len)
> +{
> +	struct wpa_mlo_link_hdr *link_kde_hdr;
> +	size_t rsn_ie_len = 0, rsnxe_len = 0;
> +	const u8 *rsn_ie = NULL, *rsnxe = NULL;
> +
> +	if (!link_kde || link_kde_len < sizeof(*link_kde_hdr)) {
> +		wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
> +			"WPA MLO: Invalid link KDE for link ID %d",
> +			link_id);
> +		return -1;
> +	}
> +
> +	link_kde_hdr = (struct wpa_mlo_link_hdr *) link_kde;
> +
> +	if (os_memcmp(sm->links[link_id].bssid, link_kde_hdr->mac,
> ETH_ALEN)) {
> +		wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
> +			"WPA MLO: Link MAC address not matching with
> assoc response");
> +		return -1;
> +	}
> +

Add the link ID to the prints.

> +	if (link_kde_hdr->rsne_present) {
> +		rsn_ie = link_kde + sizeof(*link_kde_hdr);
> +		if (link_kde_len < (sizeof(*link_kde_hdr) + 2) ||
> +		    link_kde_len < (sizeof(*link_kde_hdr) + 2 + rsn_ie[1]))
> +			return -1;
> +
> +		rsn_ie_len = rsn_ie[1] + 2;
> +	}
> +
> +	if (link_kde_hdr->rsnxe_present) {
> +		rsnxe = link_kde + sizeof(*link_kde_hdr) + rsn_ie_len;
> +		if (link_kde_len < (sizeof(*link_kde_hdr) + rsn_ie_len + 2) ||
> +		    link_kde_len < (sizeof(*link_kde_hdr) + rsn_ie_len + 2 +
> +				    rsnxe[1]))
> +			return -1;
> +
> +		rsnxe_len = rsnxe[1] + 2;
> +	}
> +
> +	if (sm->links[link_id].ap_rsn_ie == NULL) {

Is it valid to have a WPA SM set with MLO without RSN being negotiated during association? I think this should be
checked when setting the ML information.

> +		wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
> +			"WPA MLO: No RSN IE AP link ID %u known. "
> +			"Trying to get from scan results", link_id);
> +		if (wpa_sm_get_link_beacon_ie(sm, link_id) < 0) {
> +			wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
> +				"WPA MLO: Could not find AP from "
> +				"the scan results");
> +			return -1;
> +		}
> +		wpa_msg(sm->ctx->msg_ctx, MSG_DEBUG,
> +			"WPA MLO: Found the current AP from updated scan
> results");
> +	}
> +
> +	if (rsn_ie == NULL && sm->links[link_id].ap_rsn_ie) {
> +		wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
> +			"WPA MLO: IE in 3/4 msg does not match with IE in
> Beacon/ProbeResp (no IE?) for link ID %u",
> +			link_id);
> +		return -1;
> +	}
> +
> +	if (rsn_ie && sm->links[link_id].ap_rsn_ie &&
> +	    wpa_compare_rsn_ie(wpa_key_mgmt_ft(sm->key_mgmt),
> +			       sm->links[link_id].ap_rsn_ie,
> +			       sm->links[link_id].ap_rsn_ie_len,
> +			       rsn_ie, rsn_ie_len)) {
> +		wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
> +			"WPA MLO: IE in 3/4 msg does not match with IE in
> Beacon/ProbeResp for link ID %u",
> +			link_id);
> +		wpa_hexdump(MSG_INFO, "RSNE in Beacon/ProbeResp",
> +			    sm->links[link_id].ap_rsnxe,
> +			    sm->links[link_id].ap_rsnxe_len);
> +		wpa_hexdump(MSG_INFO, "RSNE in EAPOL-Key msg 3/4",
> +			    rsn_ie, rsn_ie_len);
> +		return -1;
> +	}
> +
> +	if ((sm->links[link_id].ap_rsnxe && !rsnxe) ||
> +	    (!sm->links[link_id].ap_rsnxe && rsnxe) ||
> +	    (sm->links[link_id].ap_rsnxe && rsnxe &&
> +	     (sm->links[link_id].ap_rsnxe_len != rsnxe_len ||
> +	      os_memcmp(sm->links[link_id].ap_rsnxe, rsnxe,
> +			sm->links[link_id].ap_rsnxe_len) != 0))) {
> +		wpa_msg(sm->ctx->msg_ctx, MSG_INFO,
> +			"WPA MLO: RSNXE mismatch between
> Beacon/ProbeResp and EAPOL-Key msg 3/4 for link ID %u",
> +			link_id);
> +		wpa_hexdump(MSG_INFO, "RSNXE in Beacon/ProbeResp",
> +			    sm->links[link_id].ap_rsnxe,
> +			    sm->links[link_id].ap_rsnxe_len);
> +		wpa_hexdump(MSG_INFO, "RSNXE in EAPOL-Key msg 3/4",
> +			    rsnxe, rsnxe_len);
> +		wpa_sm_deauthenticate(sm,
> WLAN_REASON_IE_IN_4WAY_DIFFERS);
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
> +
> +static int wpa_validate_mlo_kdes(struct wpa_sm *sm,
> +				 u8 link_id, struct wpa_eapol_ie_parse *ie) {
> +	if (ie->mlo_igtk[link_id] &&
> +	    sm->mgmt_group_cipher != WPA_CIPHER_GTK_NOT_USED &&
> +	    wpa_cipher_valid_mgmt_group(sm->mgmt_group_cipher) &&
> +	    ie->mlo_igtk_len[link_id] != sizeof(struct wpa_mlo_igtk_hdr) +
> +	    (unsigned int) wpa_cipher_key_len(sm->mgmt_group_cipher)) {
> +		wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
> +			"WPA MLO: Invalid IGTK KDE length %lu for link ID
> %u",
> +			(unsigned long) ie->mlo_igtk_len, link_id);
> +		return -1;
> +	}
> +

What about BIGTK MLO KDE validation?

Regards,

Ilan.