package/network/services/hostapd/patches/005-hostapd-Avoid-key-reinstallation-in-FT-handshake.patch

   1 From: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
   2 Date: Fri, 14 Jul 2017 15:15:35 +0200
   3 Subject: [PATCH] hostapd: Avoid key reinstallation in FT handshake
   4
   5 Do not reinstall TK to the driver during Reassociation Response frame
   6 processing if the first attempt of setting the TK succeeded. This avoids
   7 issues related to clearing the TX/RX PN that could result in reusing
   8 same PN values for transmitted frames (e.g., due to CCM nonce reuse and
   9 also hitting replay protection on the receiver) and accepting replayed
  10 frames on RX side.
  11
  12 This issue was introduced by the commit
  13 0e84c25434e6a1f283c7b4e62e483729085b78d2 ('FT: Fix PTK configuration in
  14 authenticator') which allowed wpa_ft_install_ptk() to be called multiple
  15 times with the same PTK. While the second configuration attempt is
  16 needed with some drivers, it must be done only if the first attempt
  17 failed.
  18
  19 Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
  20 ---
  21
  22 --- a/src/ap/ieee802_11.c
  23 +++ b/src/ap/ieee802_11.c
  24 @@ -2154,6 +2154,7 @@ static int add_associated_sta(struct hos
  25  {
  26         struct ieee80211_ht_capabilities ht_cap;
  27         struct ieee80211_vht_capabilities vht_cap;
  28 +       int set = 1;
  29
  30         /*
  31          * Remove the STA entry to ensure the STA PS state gets cleared and
  32 @@ -2161,9 +2162,18 @@ static int add_associated_sta(struct hos
  33          * FT-over-the-DS, where a station re-associates back to the same AP but
  34          * skips the authentication flow, or if working with a driver that
  35          * does not support full AP client state.
  36 +        *
  37 +        * Skip this if the STA has already completed FT reassociation and the
  38 +        * TK has been configured since the TX/RX PN must not be reset to 0 for
  39 +        * the same key.
  40          */
  41 -       if (!sta->added_unassoc)
  42 +       if (!sta->added_unassoc &&
  43 +           (!(sta->flags & WLAN_STA_AUTHORIZED) ||
  44 +            !wpa_auth_sta_ft_tk_already_set(sta->wpa_sm))) {
  45                 hostapd_drv_sta_remove(hapd, sta->addr);
  46 +               wpa_auth_sm_event(sta->wpa_sm, WPA_DRV_STA_REMOVED);
  47 +               set = 0;
  48 +       }
  49
  50  #ifdef CONFIG_IEEE80211N
  51         if (sta->flags & WLAN_STA_HT)
  52 @@ -2186,11 +2196,11 @@ static int add_associated_sta(struct hos
  53                             sta->flags & WLAN_STA_VHT ? &vht_cap : NULL,
  54                             sta->flags | WLAN_STA_ASSOC, sta->qosinfo,
  55                             sta->vht_opmode, sta->p2p_ie ? 1 : 0,
  56 -                           sta->added_unassoc)) {
  57 +                           set)) {
  58                 hostapd_logger(hapd, sta->addr,
  59                                HOSTAPD_MODULE_IEEE80211, HOSTAPD_LEVEL_NOTICE,
  60                                "Could not %s STA to kernel driver",
  61 -                              sta->added_unassoc ? "set" : "add");
  62 +                              set ? "set" : "add");
  63
  64                 if (sta->added_unassoc) {
  65                         hostapd_drv_sta_remove(hapd, sta->addr);
  66 --- a/src/ap/wpa_auth.c
  67 +++ b/src/ap/wpa_auth.c
  68 @@ -1751,6 +1751,9 @@ int wpa_auth_sm_event(struct wpa_state_m
  69  #else /* CONFIG_IEEE80211R_AP */
  70                 break;
  71  #endif /* CONFIG_IEEE80211R_AP */
  72 +       case WPA_DRV_STA_REMOVED:
  73 +               sm->tk_already_set = FALSE;
  74 +               return 0;
  75         }
  76
  77  #ifdef CONFIG_IEEE80211R_AP
  78 @@ -3725,6 +3728,14 @@ int wpa_auth_sta_wpa_version(struct wpa_
  79  }
  80
  81
  82 +int wpa_auth_sta_ft_tk_already_set(struct wpa_state_machine *sm)
  83 +{
  84 +       if (!sm || !wpa_key_mgmt_ft(sm->wpa_key_mgmt))
  85 +               return 0;
  86 +       return sm->tk_already_set;
  87 +}
  88 +
  89 +
  90  int wpa_auth_sta_clear_pmksa(struct wpa_state_machine *sm,
  91                              struct rsn_pmksa_cache_entry *entry)
  92  {
  93 --- a/src/ap/wpa_auth_ft.c
  94 +++ b/src/ap/wpa_auth_ft.c
  95 @@ -794,6 +794,14 @@ void wpa_ft_install_ptk(struct wpa_state
  96                 return;
  97         }
  98
  99 +       if (sm->tk_already_set) {
 100 +               /* Must avoid TK reconfiguration to prevent clearing of TX/RX
 101 +                * PN in the driver */
 102 +               wpa_printf(MSG_DEBUG,
 103 +                          "FT: Do not re-install same PTK to the driver");
 104 +               return;
 105 +       }
 106 +
 107         /* FIX: add STA entry to kernel/driver here? The set_key will fail
 108          * most likely without this.. At the moment, STA entry is added only
 109          * after association has been completed. This function will be called
 110 @@ -806,6 +814,7 @@ void wpa_ft_install_ptk(struct wpa_state
 111
 112         /* FIX: MLME-SetProtection.Request(TA, Tx_Rx) */
 113         sm->pairwise_set = TRUE;
 114 +       sm->tk_already_set = TRUE;
 115  }
 116
 117
 118 @@ -1002,6 +1011,7 @@ static int wpa_ft_process_auth_req(struc
 119
 120         sm->pairwise = pairwise;
 121         sm->PTK_valid = TRUE;
 122 +       sm->tk_already_set = FALSE;
 123         wpa_ft_install_ptk(sm);
 124
 125         buflen = 2 + sizeof(struct rsn_mdie) + 2 + sizeof(struct rsn_ftie) +
 126 --- a/src/ap/wpa_auth.h
 127 +++ b/src/ap/wpa_auth.h
 128 @@ -268,7 +268,7 @@ void wpa_receive(struct wpa_authenticato
 129                  u8 *data, size_t data_len);
 130  enum wpa_event {
 131         WPA_AUTH, WPA_ASSOC, WPA_DISASSOC, WPA_DEAUTH, WPA_REAUTH,
 132 -       WPA_REAUTH_EAPOL, WPA_ASSOC_FT
 133 +       WPA_REAUTH_EAPOL, WPA_ASSOC_FT, WPA_DRV_STA_REMOVED
 134  };
 135  void wpa_remove_ptk(struct wpa_state_machine *sm);
 136  int wpa_auth_sm_event(struct wpa_state_machine *sm, enum wpa_event event);
 137 @@ -281,6 +281,7 @@ int wpa_auth_pairwise_set(struct wpa_sta
 138  int wpa_auth_get_pairwise(struct wpa_state_machine *sm);
 139  int wpa_auth_sta_key_mgmt(struct wpa_state_machine *sm);
 140  int wpa_auth_sta_wpa_version(struct wpa_state_machine *sm);
 141 +int wpa_auth_sta_ft_tk_already_set(struct wpa_state_machine *sm);
 142  int wpa_auth_sta_clear_pmksa(struct wpa_state_machine *sm,
 143                              struct rsn_pmksa_cache_entry *entry);
 144  struct rsn_pmksa_cache_entry *
 145 --- a/src/ap/wpa_auth_i.h
 146 +++ b/src/ap/wpa_auth_i.h
 147 @@ -65,6 +65,7 @@ struct wpa_state_machine {
 148         struct wpa_ptk PTK;
 149         Boolean PTK_valid;
 150         Boolean pairwise_set;
 151 +       Boolean tk_already_set;
 152         int keycount;
 153         Boolean Pair;
 154         struct wpa_key_replay_counter {