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d7d57745 MT |
1 | From cf4cab804c7afd5c45505528a8d16e46163243a2 Mon Sep 17 00:00:00 2001 |
2 | From: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be> | |
3 | Date: Fri, 14 Jul 2017 15:15:35 +0200 | |
4 | Subject: [PATCH 1/8] hostapd: Avoid key reinstallation in FT handshake | |
5 | ||
6 | Do not reinstall TK to the driver during Reassociation Response frame | |
7 | processing if the first attempt of setting the TK succeeded. This avoids | |
8 | issues related to clearing the TX/RX PN that could result in reusing | |
9 | same PN values for transmitted frames (e.g., due to CCM nonce reuse and | |
10 | also hitting replay protection on the receiver) and accepting replayed | |
11 | frames on RX side. | |
12 | ||
13 | This issue was introduced by the commit | |
14 | 0e84c25434e6a1f283c7b4e62e483729085b78d2 ('FT: Fix PTK configuration in | |
15 | authenticator') which allowed wpa_ft_install_ptk() to be called multiple | |
16 | times with the same PTK. While the second configuration attempt is | |
17 | needed with some drivers, it must be done only if the first attempt | |
18 | failed. | |
19 | ||
20 | Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be> | |
21 | --- | |
22 | src/ap/ieee802_11.c | 16 +++++++++++++--- | |
23 | src/ap/wpa_auth.c | 11 +++++++++++ | |
24 | src/ap/wpa_auth.h | 3 ++- | |
25 | src/ap/wpa_auth_ft.c | 10 ++++++++++ | |
26 | src/ap/wpa_auth_i.h | 1 + | |
27 | 5 files changed, 37 insertions(+), 4 deletions(-) | |
28 | ||
29 | diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c | |
30 | index 4e04169..333035f 100644 | |
31 | --- a/src/ap/ieee802_11.c | |
32 | +++ b/src/ap/ieee802_11.c | |
33 | @@ -1841,6 +1841,7 @@ static int add_associated_sta(struct hostapd_data *hapd, | |
34 | { | |
35 | struct ieee80211_ht_capabilities ht_cap; | |
36 | struct ieee80211_vht_capabilities vht_cap; | |
37 | + int set = 1; | |
38 | ||
39 | /* | |
40 | * Remove the STA entry to ensure the STA PS state gets cleared and | |
41 | @@ -1848,9 +1849,18 @@ static int add_associated_sta(struct hostapd_data *hapd, | |
42 | * FT-over-the-DS, where a station re-associates back to the same AP but | |
43 | * skips the authentication flow, or if working with a driver that | |
44 | * does not support full AP client state. | |
45 | + * | |
46 | + * Skip this if the STA has already completed FT reassociation and the | |
47 | + * TK has been configured since the TX/RX PN must not be reset to 0 for | |
48 | + * the same key. | |
49 | */ | |
50 | - if (!sta->added_unassoc) | |
51 | + if (!sta->added_unassoc && | |
52 | + (!(sta->flags & WLAN_STA_AUTHORIZED) || | |
53 | + !wpa_auth_sta_ft_tk_already_set(sta->wpa_sm))) { | |
54 | hostapd_drv_sta_remove(hapd, sta->addr); | |
55 | + wpa_auth_sm_event(sta->wpa_sm, WPA_DRV_STA_REMOVED); | |
56 | + set = 0; | |
57 | + } | |
58 | ||
59 | #ifdef CONFIG_IEEE80211N | |
60 | if (sta->flags & WLAN_STA_HT) | |
61 | @@ -1873,11 +1883,11 @@ static int add_associated_sta(struct hostapd_data *hapd, | |
62 | sta->flags & WLAN_STA_VHT ? &vht_cap : NULL, | |
63 | sta->flags | WLAN_STA_ASSOC, sta->qosinfo, | |
64 | sta->vht_opmode, sta->p2p_ie ? 1 : 0, | |
65 | - sta->added_unassoc)) { | |
66 | + set)) { | |
67 | hostapd_logger(hapd, sta->addr, | |
68 | HOSTAPD_MODULE_IEEE80211, HOSTAPD_LEVEL_NOTICE, | |
69 | "Could not %s STA to kernel driver", | |
70 | - sta->added_unassoc ? "set" : "add"); | |
71 | + set ? "set" : "add"); | |
72 | ||
73 | if (sta->added_unassoc) { | |
74 | hostapd_drv_sta_remove(hapd, sta->addr); | |
75 | diff --git a/src/ap/wpa_auth.c b/src/ap/wpa_auth.c | |
76 | index 3587086..707971d 100644 | |
77 | --- a/src/ap/wpa_auth.c | |
78 | +++ b/src/ap/wpa_auth.c | |
79 | @@ -1745,6 +1745,9 @@ int wpa_auth_sm_event(struct wpa_state_machine *sm, enum wpa_event event) | |
80 | #else /* CONFIG_IEEE80211R */ | |
81 | break; | |
82 | #endif /* CONFIG_IEEE80211R */ | |
83 | + case WPA_DRV_STA_REMOVED: | |
84 | + sm->tk_already_set = FALSE; | |
85 | + return 0; | |
86 | } | |
87 | ||
88 | #ifdef CONFIG_IEEE80211R | |
89 | @@ -3250,6 +3253,14 @@ int wpa_auth_sta_wpa_version(struct wpa_state_machine *sm) | |
90 | } | |
91 | ||
92 | ||
93 | +int wpa_auth_sta_ft_tk_already_set(struct wpa_state_machine *sm) | |
94 | +{ | |
95 | + if (!sm || !wpa_key_mgmt_ft(sm->wpa_key_mgmt)) | |
96 | + return 0; | |
97 | + return sm->tk_already_set; | |
98 | +} | |
99 | + | |
100 | + | |
101 | int wpa_auth_sta_clear_pmksa(struct wpa_state_machine *sm, | |
102 | struct rsn_pmksa_cache_entry *entry) | |
103 | { | |
104 | diff --git a/src/ap/wpa_auth.h b/src/ap/wpa_auth.h | |
105 | index 0de8d97..97461b0 100644 | |
106 | --- a/src/ap/wpa_auth.h | |
107 | +++ b/src/ap/wpa_auth.h | |
108 | @@ -267,7 +267,7 @@ void wpa_receive(struct wpa_authenticator *wpa_auth, | |
109 | u8 *data, size_t data_len); | |
110 | enum wpa_event { | |
111 | WPA_AUTH, WPA_ASSOC, WPA_DISASSOC, WPA_DEAUTH, WPA_REAUTH, | |
112 | - WPA_REAUTH_EAPOL, WPA_ASSOC_FT | |
113 | + WPA_REAUTH_EAPOL, WPA_ASSOC_FT, WPA_DRV_STA_REMOVED | |
114 | }; | |
115 | void wpa_remove_ptk(struct wpa_state_machine *sm); | |
116 | int wpa_auth_sm_event(struct wpa_state_machine *sm, enum wpa_event event); | |
117 | @@ -280,6 +280,7 @@ int wpa_auth_pairwise_set(struct wpa_state_machine *sm); | |
118 | int wpa_auth_get_pairwise(struct wpa_state_machine *sm); | |
119 | int wpa_auth_sta_key_mgmt(struct wpa_state_machine *sm); | |
120 | int wpa_auth_sta_wpa_version(struct wpa_state_machine *sm); | |
121 | +int wpa_auth_sta_ft_tk_already_set(struct wpa_state_machine *sm); | |
122 | int wpa_auth_sta_clear_pmksa(struct wpa_state_machine *sm, | |
123 | struct rsn_pmksa_cache_entry *entry); | |
124 | struct rsn_pmksa_cache_entry * | |
125 | diff --git a/src/ap/wpa_auth_ft.c b/src/ap/wpa_auth_ft.c | |
126 | index 42242a5..e63b99a 100644 | |
127 | --- a/src/ap/wpa_auth_ft.c | |
128 | +++ b/src/ap/wpa_auth_ft.c | |
129 | @@ -780,6 +780,14 @@ void wpa_ft_install_ptk(struct wpa_state_machine *sm) | |
130 | return; | |
131 | } | |
132 | ||
133 | + if (sm->tk_already_set) { | |
134 | + /* Must avoid TK reconfiguration to prevent clearing of TX/RX | |
135 | + * PN in the driver */ | |
136 | + wpa_printf(MSG_DEBUG, | |
137 | + "FT: Do not re-install same PTK to the driver"); | |
138 | + return; | |
139 | + } | |
140 | + | |
141 | /* FIX: add STA entry to kernel/driver here? The set_key will fail | |
142 | * most likely without this.. At the moment, STA entry is added only | |
143 | * after association has been completed. This function will be called | |
144 | @@ -792,6 +800,7 @@ void wpa_ft_install_ptk(struct wpa_state_machine *sm) | |
145 | ||
146 | /* FIX: MLME-SetProtection.Request(TA, Tx_Rx) */ | |
147 | sm->pairwise_set = TRUE; | |
148 | + sm->tk_already_set = TRUE; | |
149 | } | |
150 | ||
151 | ||
152 | @@ -898,6 +907,7 @@ static int wpa_ft_process_auth_req(struct wpa_state_machine *sm, | |
153 | ||
154 | sm->pairwise = pairwise; | |
155 | sm->PTK_valid = TRUE; | |
156 | + sm->tk_already_set = FALSE; | |
157 | wpa_ft_install_ptk(sm); | |
158 | ||
159 | buflen = 2 + sizeof(struct rsn_mdie) + 2 + sizeof(struct rsn_ftie) + | |
160 | diff --git a/src/ap/wpa_auth_i.h b/src/ap/wpa_auth_i.h | |
161 | index 72b7eb3..7fd8f05 100644 | |
162 | --- a/src/ap/wpa_auth_i.h | |
163 | +++ b/src/ap/wpa_auth_i.h | |
164 | @@ -65,6 +65,7 @@ struct wpa_state_machine { | |
165 | struct wpa_ptk PTK; | |
166 | Boolean PTK_valid; | |
167 | Boolean pairwise_set; | |
168 | + Boolean tk_already_set; | |
169 | int keycount; | |
170 | Boolean Pair; | |
171 | struct wpa_key_replay_counter { | |
172 | -- | |
173 | 2.7.4 | |
174 |