ft: implement offchannel authentication

A new API was added, ft_authenticate, which will send an
authentication frame offchannel via CMD_FRAME. This bypasses
the kernel's authentication state allowing multiple auth
attempts to take place without disconnecting.

src/ft.c

@@ -37,6 +37,8 @@
 #include "src/util.h"
 #include "src/netdev.h"
 #include "src/module.h"
+#include "src/offchannel.h"
+#include "src/wiphy.h"
 
 static ft_tx_frame_func_t tx_frame = NULL;
 static ft_tx_associate_func_t tx_assoc = NULL;
@@ -52,6 +54,7 @@ struct ft_info {
 	uint8_t *authenticator_ie;
 	uint8_t prev_bssid[6];
 	uint32_t frequency;
+	uint32_t offchannel_id;
 
 	struct ie_ft_info ft_info;
 
@@ -1169,6 +1172,101 @@ failed:
 	return ret;
 }
 
+void __ft_rx_authenticate(uint32_t ifindex, const uint8_t *frame,
+				size_t frame_len)
+{
+	struct netdev *netdev = netdev_find(ifindex);
+	struct handshake_state *hs = netdev_get_handshake(netdev);
+	struct ft_info *info;
+	uint16_t status;
+	const uint8_t *ies;
+	size_t ies_len;
+
+	info = ft_info_find(ifindex, NULL);
+	if (!info)
+		return;
+
+	if (!ft_parse_authentication_resp_frame(frame, frame_len,
+					info->spa, info->aa, info->aa, 2,
+					&status, &ies, &ies_len))
+		return;
+
+	/* Verified to be expected target, offchannel can be canceled */
+	offchannel_cancel(netdev_get_wdev_id(netdev), info->offchannel_id);
+
+	if (status != 0)
+		return;
+
+	if (!ft_parse_ies(info, hs, ies, ies_len))
+		return;
+
+	info->parsed = true;
+
+	return;
+}
+
+static void ft_send_authenticate(void *user_data)
+{
+	struct ft_info *info = user_data;
+	struct netdev *netdev = netdev_find(info->ifindex);
+	struct handshake_state *hs = netdev_get_handshake(netdev);
+	uint8_t ies[256];
+	size_t len;
+	struct iovec iov[2];
+	struct mmpdu_authentication auth;
+
+	/* Authentication body */
+	auth.algorithm = L_CPU_TO_LE16(MMPDU_AUTH_ALGO_FT);
+	auth.transaction_sequence = L_CPU_TO_LE16(1);
+	auth.status = L_CPU_TO_LE16(0);
+
+	iov[0].iov_base = &auth;
+	iov[0].iov_len = sizeof(struct mmpdu_authentication);
+
+	if (!ft_build_authenticate_ies(hs, hs->supplicant_ocvc, info->snonce,
+					ies, &len))
+		return;
+
+	iov[1].iov_base = ies;
+	iov[1].iov_len = len;
+
+	tx_frame(info->ifindex, 0x00b0, info->frequency, info->aa, iov, 2);
+}
+
+static void ft_authenticate_destroy(int error, void *user_data)
+{
+	struct ft_info *info = user_data;
+
+	info->offchannel_id = 0;
+}
+
+/*
+ * There is no callback here because its assumed that another work item will
+ * be inserted following this call which will check if authentication succeeded
+ * via ft_associate.
+ *
+ * If the netdev goes away while authentication is in-flight station will clear
+ * the authentications during cleanup, and in turn cancel the offchannel
+ * request.
+ */
+int ft_authenticate(uint32_t ifindex, const struct scan_bss *target)
+{
+	struct netdev *netdev = netdev_find(ifindex);
+	struct handshake_state *hs = netdev_get_handshake(netdev);
+	struct ft_info *info = ft_info_new(hs, target);
+
+	info->offchannel_id = offchannel_start(netdev_get_wdev_id(netdev),
+						WIPHY_WORK_PRIORITY_FT,
+						target->frequency,
+						200, ft_send_authenticate, info,
+						ft_authenticate_destroy);
+	ft_clear_authentications(ifindex);
+
+	l_queue_push_tail(info_list, info);
+
+	return 0;
+}
+
 int ft_associate(uint32_t ifindex, const uint8_t *addr)
 {
 	struct netdev *netdev = netdev_find(ifindex);
@@ -1205,6 +1303,10 @@ static bool remove_ifindex(void *data, void *user_data)
 	if (info->ifindex != ifindex)
 		return false;
 
+	if (info->offchannel_id)
+		offchannel_cancel(netdev_get_wdev_id(netdev_find(ifindex)),
+					info->offchannel_id);
+
 	ft_info_destroy(info);
 	return true;
 }

src/ft.h

@@ -85,7 +85,10 @@ void __ft_set_tx_associate_func(ft_tx_associate_func_t func);
 int __ft_rx_associate(uint32_t ifindex, const uint8_t *frame,
 			size_t frame_len);
 void __ft_rx_action(uint32_t ifindex, const uint8_t *frame, size_t frame_len);
+void __ft_rx_authenticate(uint32_t ifindex, const uint8_t *frame,
+				size_t frame_len);
 
 void ft_clear_authentications(uint32_t ifindex);
 int ft_action(uint32_t ifindex, uint32_t freq, const struct scan_bss *target);
 int ft_associate(uint32_t ifindex, const uint8_t *addr);
+int ft_authenticate(uint32_t ifindex, const struct scan_bss *target);