[PATCH] ap: add vendor quirk for reused nonce in handshake

berend <[email protected]> Wed, 24 Dec 2025 10:28:40 +0000
Newsgroups	dev.linux.lists.iwd
Message-ID	<[email protected]>
commit 486cd7b1cd20bfa81437d89cdd7c8f8df7e23bfa
Author: Berend De Schouwer <[email protected]>
Date:   Wed Dec 24 11:28:17 2025 +0200

    ap: add vendor quirk for reused nonce in handshake
    
    Add a vendor quirk when IWD is an AP, to allow some
    Garmin IoT devices to connect.
    
    handshake_reuse_nonce:
      When a supplicant does a handshake, the nonce in message 4 should
      be set to zero.  On some devices it's left identical to message
2.

diff --git a/src/ap.c b/src/ap.c
index af6a1709..1f805a81 100644
--- a/src/ap.c
+++ b/src/ap.c
@@ -59,6 +59,7 @@
 #include "src/diagnostic.h"
 #include "src/band.h"
 #include "src/common.h"
+#include "src/vendor_quirks.h"
 
 struct ap_state {
        struct netdev *netdev;
@@ -143,6 +144,7 @@ struct sta_state {
        struct l_dhcp_lease *ip_alloc_lease;
        bool ip_alloc_sent;
        uint64_t rekey_time;
+       struct vendor_quirk vendor_quirks;
 
        bool ht_support : 1;
        bool ht_greenfield : 1;
@@ -1384,6 +1386,7 @@ static void ap_start_handshake(struct sta_state
*sta, bool use_eapol_start,
        handshake_state_set_ssid(sta->hs, (void *) ap->ssid, strlen(ap-
>ssid));
        handshake_state_set_authenticator_address(sta->hs, own_addr);
        handshake_state_set_supplicant_address(sta->hs, sta->addr);
+       handshake_state_set_vendor_quirks(sta->hs, sta->vendor_quirks);
 
        ap_set_rsn_info(ap, &rsn);
        /*
@@ -2974,6 +2977,7 @@ static void ap_handle_new_station(struct ap_state
*ap, struct l_genl_msg *msg)
        const void *data;
        const uint8_t *mac = NULL;
        uint8_t *assoc_rsne = NULL;
+       const char *vendor_quirks;
 
        if (!l_genl_attr_init(&attr, msg))
                return;
@@ -3014,6 +3018,13 @@ static void ap_handle_new_station(struct
ap_state *ap, struct l_genl_msg *msg)
        sta->assoc_rsne = assoc_rsne;
        sta->aid = ++ap->last_aid;
 
+       vendor_quirks_append_for_mac(sta->addr, &sta->vendor_quirks);
+
+       vendor_quirks = vendor_quirks_to_string(sta->vendor_quirks);
+       if (vendor_quirks)
+               l_debug("vendor quirks for "MAC": %s",
+                               MAC_STR(sta->addr), vendor_quirks);
+
        sta->associated = true;
 
        if (!ap->sta_states)
diff --git a/src/eapol.c b/src/eapol.c
index ab77746f..b603ae39 100644
--- a/src/eapol.c
+++ b/src/eapol.c
@@ -605,7 +605,8 @@ bool eapol_verify_ptk_3_of_4(const struct eapol_key
*ek, bool is_wpa,
        return true;
 }
 
-bool eapol_verify_ptk_4_of_4(const struct eapol_key *ek, bool is_wpa)
+bool eapol_verify_ptk_4_of_4(const struct eapol_key *ek, bool is_wpa,
+                               const uint8_t *quirk_nonce)
 {
        uint16_t key_len;
 
@@ -636,7 +637,9 @@ bool eapol_verify_ptk_4_of_4(const struct eapol_key
*ek, bool is_wpa)
        key_len = L_BE16_TO_CPU(ek->key_length);
        L_WARN_ON(key_len != 0);
 
-       VERIFY_IS_ZERO(ek->key_nonce);
+       if ((!quirk_nonce) || memcmp(ek->key_nonce, quirk_nonce,
+                                       sizeof(ek->key_nonce)))
+               VERIFY_IS_ZERO(ek->key_nonce);
        VERIFY_IS_ZERO(ek->eapol_key_iv);
        VERIFY_IS_ZERO(ek->key_rsc);
        VERIFY_IS_ZERO(ek->reserved);
@@ -2122,10 +2125,15 @@ static void eapol_handle_ptk_4_of_4(struct
eapol_sm *sm,
                                        const struct eapol_key *ek)
 {
        const uint8_t *kck;
+       const uint8_t *quirk_nonce = NULL;
 
        l_debug("ifindex=%u", sm->handshake->ifindex);
 
-       if (!eapol_verify_ptk_4_of_4(ek, false))
+       if (sm->handshake->vendor_quirks.handshake_nonce_reuse &&
+                       sm->handshake->have_snonce)
+               quirk_nonce = sm->handshake->snonce;
+
+       if (!eapol_verify_ptk_4_of_4(ek, false, quirk_nonce))
                return;
 
        if (L_BE64_TO_CPU(ek->key_replay_counter) != sm-
>replay_counter)
diff --git a/src/eapol.h b/src/eapol.h
index 43dc224d..36946017 100644
--- a/src/eapol.h
+++ b/src/eapol.h
@@ -70,7 +70,8 @@ bool eapol_verify_ptk_1_of_4(const struct eapol_key
*ek, size_t mic_len,
 bool eapol_verify_ptk_2_of_4(const struct eapol_key *ek, bool
ptk_complete);
 bool eapol_verify_ptk_3_of_4(const struct eapol_key *ek, bool is_wpa,
                                size_t mic_len);
-bool eapol_verify_ptk_4_of_4(const struct eapol_key *ek, bool is_wpa);
+bool eapol_verify_ptk_4_of_4(const struct eapol_key *ek, bool is_wpa,
+                               const uint8_t *quirk_nonce);
 bool eapol_verify_gtk_1_of_2(const struct eapol_key *ek, bool is_wpa,
                                size_t mic_len);
 bool eapol_verify_gtk_2_of_2(const struct eapol_key *ek, bool is_wpa);
diff --git a/src/vendor_quirks.c b/src/vendor_quirks.c
index 4fba0c33..001fcb13 100644
--- a/src/vendor_quirks.c
+++ b/src/vendor_quirks.c
@@ -47,6 +47,17 @@ static const struct {
        },
 };
 
+static const struct {
+       uint8_t mac[3];
+       struct vendor_quirk quirks;
+} mac_quirk_db[] = {
+       {
+               /* Garmin International */
+               { 0x90, 0xf1, 0x57 },
+               { .handshake_nonce_reuse = true },
+       },
+};
+
 void vendor_quirks_append_for_oui(const uint8_t *oui,
                                        struct vendor_quirk *quirks)
 {
@@ -65,6 +76,22 @@ void vendor_quirks_append_for_oui(const uint8_t
*oui,
        }
 }
 
+void vendor_quirks_append_for_mac(const uint8_t *mac,
+                                       struct vendor_quirk *quirks)
+{
+       size_t i;
+
+       for (i = 0; i < L_ARRAY_SIZE(mac_quirk_db); i++) {
+               const struct vendor_quirk *quirk =
&mac_quirk_db[i].quirks;
+
+               if (memcmp(mac_quirk_db[i].mac, mac, 3))
+                       continue;
+
+               quirks->handshake_nonce_reuse |=
+                               quirk->handshake_nonce_reuse;
+       }
+}
+
 const char *vendor_quirks_to_string(struct vendor_quirk quirks)
 {
        static char out[1024];
@@ -77,6 +104,9 @@ const char *vendor_quirks_to_string(struct
vendor_quirk quirks)
        if (quirks.replay_counter_mismatch)
                s += snprintf(pos, sizeof(out) - s,
"ReplayCounterMismatch");
 
+       if (quirks.handshake_nonce_reuse)
+               s += snprintf(pos, sizeof(out) - s,
"HandshakeNonceReuse");
+
        if (!s)
                return NULL;
 
diff --git a/src/vendor_quirks.h b/src/vendor_quirks.h
index b5d726ca..0e199c3a 100644
--- a/src/vendor_quirks.h
+++ b/src/vendor_quirks.h
@@ -29,11 +29,15 @@
 struct vendor_quirk {
        bool ignore_bss_tm_candidates : 1;
        bool replay_counter_mismatch : 1;
+       bool handshake_nonce_reuse : 1;
 };
 
 void vendor_quirks_append_for_oui(const uint8_t *oui,
                                        struct vendor_quirk *quirks);
 
+void vendor_quirks_append_for_mac(const uint8_t *oui,
+                                       struct vendor_quirk *quirks);
+
 const char *vendor_quirks_to_string(struct vendor_quirk quirks);
 
 #endif /* __IWD_VENDOR_QUIRKS_H */
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