FT: Fix R0KH-R1KH protocol data length values

The FT RRB hostapd packets have a length field. For PULL frames, it
counted the bytes starting with nonce and up to the last before pad. For
RESP frames, it counted the bytes starting with nonce and up to the last
before pad except for 2 bytes. For PUSH frames, it counted the bytes
starting with nonce and up to including pad.

As rounding is done with AES encryption, including pad does not make
sense. Not including the last field before pad does not make sense
either. These were broken in the earlier addition of the 2 octet
pairwise field in commit 1b484d60e5 ('FT:
Include pairwise cipher suite in PMK-R0 SA and PMK-R1 SA').

AES encryption is not affected, as rounding hides the differences. The
packets data_length field is not used, so the differences have no effect
there.

This patch changes the constants to match the bytes used, thus excluding
the pad. To validate the changes, look at remainder modulo 8 of the sum
of the size constants and the padding sizes.

Signed-off-by: Michael Braun <michael-dev@fami-braun.de>

src/ap/wpa_auth.h

@@ -42,10 +42,11 @@ struct ft_rrb_frame {
 #define FT_PACKET_R0KH_R1KH_RESP 201
 #define FT_PACKET_R0KH_R1KH_PUSH 202
 
-#define FT_R0KH_R1KH_PULL_DATA_LEN 44
-#define FT_R0KH_R1KH_RESP_DATA_LEN 76
-#define FT_R0KH_R1KH_PUSH_DATA_LEN 88
 #define FT_R0KH_R1KH_PULL_NONCE_LEN 16
+#define FT_R0KH_R1KH_PULL_DATA_LEN (FT_R0KH_R1KH_PULL_NONCE_LEN + \
+				    WPA_PMK_NAME_LEN + FT_R1KH_ID_LEN + \
+				    ETH_ALEN)
+#define FT_R0KH_R1KH_PULL_PAD_LEN ((8 - FT_R0KH_R1KH_PULL_DATA_LEN % 8) % 8)
 
 struct ft_r0kh_r1kh_pull_frame {
 	u8 frame_type; /* RSN_REMOTE_FRAME_TYPE_FT_RRB */
@@ -57,14 +58,18 @@ struct ft_r0kh_r1kh_pull_frame {
 	u8 pmk_r0_name[WPA_PMK_NAME_LEN];
 	u8 r1kh_id[FT_R1KH_ID_LEN];
 	u8 s1kh_id[ETH_ALEN];
-	u8 pad[4]; /* 8-octet boundary for AES key wrap */
+	u8 pad[FT_R0KH_R1KH_PULL_PAD_LEN]; /* 8-octet boundary for AES block */
 	u8 key_wrap_extra[8];
 } STRUCT_PACKED;
 
+#define FT_R0KH_R1KH_RESP_DATA_LEN (FT_R0KH_R1KH_PULL_NONCE_LEN + \
+				    FT_R1KH_ID_LEN + ETH_ALEN + PMK_LEN + \
+				    WPA_PMK_NAME_LEN + 2)
+#define FT_R0KH_R1KH_RESP_PAD_LEN ((8 - FT_R0KH_R1KH_RESP_DATA_LEN % 8) % 8)
 struct ft_r0kh_r1kh_resp_frame {
 	u8 frame_type; /* RSN_REMOTE_FRAME_TYPE_FT_RRB */
 	u8 packet_type; /* FT_PACKET_R0KH_R1KH_RESP */
-	le16 data_length; /* little endian length of data (76) */
+	le16 data_length; /* little endian length of data (78) */
 	u8 ap_address[ETH_ALEN];
 
 	u8 nonce[FT_R0KH_R1KH_PULL_NONCE_LEN]; /* copied from pull */
@@ -73,14 +78,18 @@ struct ft_r0kh_r1kh_resp_frame {
 	u8 pmk_r1[PMK_LEN];
 	u8 pmk_r1_name[WPA_PMK_NAME_LEN];
 	le16 pairwise;
-	u8 pad[2]; /* 8-octet boundary for AES key wrap */
+	u8 pad[FT_R0KH_R1KH_RESP_PAD_LEN]; /* 8-octet boundary for AES block */
 	u8 key_wrap_extra[8];
 } STRUCT_PACKED;
 
+#define FT_R0KH_R1KH_PUSH_DATA_LEN (4 + FT_R1KH_ID_LEN + ETH_ALEN + \
+				    WPA_PMK_NAME_LEN + PMK_LEN + \
+				    WPA_PMK_NAME_LEN + 2)
+#define FT_R0KH_R1KH_PUSH_PAD_LEN ((8 - FT_R0KH_R1KH_PUSH_DATA_LEN % 8) % 8)
 struct ft_r0kh_r1kh_push_frame {
 	u8 frame_type; /* RSN_REMOTE_FRAME_TYPE_FT_RRB */
 	u8 packet_type; /* FT_PACKET_R0KH_R1KH_PUSH */
-	le16 data_length; /* little endian length of data (88) */
+	le16 data_length; /* little endian length of data (82) */
 	u8 ap_address[ETH_ALEN];
 
 	/* Encrypted with AES key-wrap */
@@ -92,7 +101,7 @@ struct ft_r0kh_r1kh_push_frame {
 	u8 pmk_r1[PMK_LEN];
 	u8 pmk_r1_name[WPA_PMK_NAME_LEN];
 	le16 pairwise;
-	u8 pad[6]; /* 8-octet boundary for AES key wrap */
+	u8 pad[FT_R0KH_R1KH_PUSH_PAD_LEN]; /* 8-octet boundary for AES block */
 	u8 key_wrap_extra[8];
 } STRUCT_PACKED;