[PATCH v2 4/9] ft: add FTE/RSNE building to ft_prepare_handshake

James Prestwood
2023-12-06T15:07:19Z

In preparation to remove ft_associate build the FTE/RSNE in
ft_prepare_handshake and set into the handshake object directly.
---
src/ft.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/src/ft.c b/src/ft.c
index 2cc611b8..358a4594 100644
--- a/src/ft.c
+++ b/src/ft.c
@@ -904,9 +904,15 @@ static void ft_info_destroy(void *data)
l_free(info);
}

-static void ft_prepare_handshake(struct ft_info *info,
+static bool ft_prepare_handshake(struct ft_info *info,
struct handshake_state *hs)
{
+ uint32_t kck_len = handshake_state_get_kck_len(hs);
+ struct ie_rsn_info rsn_info;
+ struct ie_ft_info ft_info;
+ uint8_t *fte;
+ uint8_t *rsne;
+
handshake_state_set_authenticator_address(hs, info->aa);

memcpy(hs->mde + 2, info->mde, 3);
@@ -914,7 +920,7 @@ static void ft_prepare_handshake(struct ft_info *info,
handshake_state_set_chandef(hs, NULL);

if (!hs->supplicant_ie)
- return;
+ return true;

if (info->authenticator_ie)
handshake_state_set_authenticator_ie(hs,
@@ -931,6 +937,80 @@ static void ft_prepare_handshake(struct ft_info *info,
info->ft_info.r1khid);

handshake_state_derive_ptk(hs);
+
+ /*
+ * Rebuild the RSNE to include the PMKR1Name and append
+ * MDE + FTE.
+ *
+ * 12.8.4: "If present, the RSNE shall be set as follows:
+ * - Version field shall be set to 1.
+ * - PMKID Count field shall be set to 1.
+ * - PMKID field shall contain the PMKR1Name.
+ * - All other fields shall be as specified in 8.4.2.27
+ * and 11.5.3."
+ */
+ if (ie_parse_rsne_from_data(hs->supplicant_ie,
+ hs->supplicant_ie[1] + 2,
+ &rsn_info) < 0)
+ return false;
+
+ rsn_info.num_pmkids = 1;
+ rsn_info.pmkids = hs->pmk_r1_name;
+ /* Always set OCVC false for FT for now */
+ rsn_info.ocvc = false;
+ rsne = alloca(256);
+
+ ie_build_rsne(&rsn_info, rsne);
+ handshake_state_set_supplicant_ie(hs, rsne);
+
+ /*
+ * 12.8.4: "If present, the FTE shall be set as follows:
+ * - ANonce, SNonce, R0KH-ID, and R1KH-ID shall be set to
+ * the values contained in the second message of this
+ * sequence.
+ * - The Element Count field of the MIC Control field shall
+ * be set to the number of elements protected in this
+ * frame (variable).
+ * [...]
+ * - All other fields shall be set to 0."
+ */
+ memset(&ft_info, 0, sizeof(ft_info));
+ ft_info.mic_element_count = 3;
+ memcpy(ft_info.r0khid, hs->r0khid, hs->r0khid_len);
+ ft_info.r0khid_len = hs->r0khid_len;
+ memcpy(ft_info.r1khid, hs->r1khid, 6);
+ ft_info.r1khid_present = true;
+ memcpy(ft_info.anonce, hs->anonce, 32);
+ memcpy(ft_info.snonce, hs->snonce, 32);
+
+ /*
+ * IEEE 802.11-2020 Section 13.7.1 FT reassociation in an RSN
+ *
+ * "If dot11RSNAOperatingChannelValidationActivated is true and
+ * the FTO indicates OCVC capability, the target AP shall
+ * ensure that OCI subelement of the FTE matches by ensuring
+ * that all of the following are true:
+ * - OCI subelement is present
+ * - Channel information in the OCI matches current
+ * operating channel parameters (see 12.2.9)"
+ */
+ if (hs->supplicant_ocvc && hs->chandef) {
+ oci_from_chandef(hs->chandef, ft_info.oci);
+ ft_info.oci_present = true;
+ }
+
+ fte = alloca(256);
+ ie_build_fast_bss_transition(&ft_info, kck_len, fte);
+
+ if (!ft_calculate_fte_mic(hs, 5, rsne, fte, NULL, ft_info.mic))
+ return false;
+
+ /* Rebuild the FT IE now with the MIC included */
+ ie_build_fast_bss_transition(&ft_info, kck_len, fte);
+
+ handshake_state_set_fte(hs, fte);
+
+ return true;
}

static bool ft_send_action(struct wiphy_radio_work_item *work)
--
2.34.1