1 From 927f891007c402fefd1ff384645b3f07597c3ede Mon Sep 17 00:00:00 2001
2 From: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
3 Date: Wed, 12 Jul 2017 16:03:24 +0200
4 Subject: [PATCH 2/8] Prevent reinstallation of an already in-use group key
5
6 Track the current GTK and IGTK that is in use and when receiving a
7 (possibly retransmitted) Group Message 1 or WNM-Sleep Mode Response, do
8 not install the given key if it is already in use. This prevents an
9 attacker from trying to trick the client into resetting or lowering the
10 sequence counter associated to the group key.
11
12 Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
13 ---
14 src/common/wpa_common.h | 11 +++++
15 src/rsn_supp/wpa.c | 116 ++++++++++++++++++++++++++++++------------------
16 src/rsn_supp/wpa_i.h | 4 ++
17 3 files changed, 87 insertions(+), 44 deletions(-)
18
19 diff --git a/src/common/wpa_common.h b/src/common/wpa_common.h
20 index af1d0f0..d200285 100644
21 --- a/src/common/wpa_common.h
22 +++ b/src/common/wpa_common.h
23 @@ -217,6 +217,17 @@ struct wpa_ptk {
24 size_t tk_len;
25 };
26
27 +struct wpa_gtk {
28 + u8 gtk[WPA_GTK_MAX_LEN];
29 + size_t gtk_len;
30 +};
31 +
32 +#ifdef CONFIG_IEEE80211W
33 +struct wpa_igtk {
34 + u8 igtk[WPA_IGTK_MAX_LEN];
35 + size_t igtk_len;
36 +};
37 +#endif /* CONFIG_IEEE80211W */
38
39 /* WPA IE version 1
40 * 00-50-f2:1 (OUI:OUI type)
41 diff --git a/src/rsn_supp/wpa.c b/src/rsn_supp/wpa.c
42 index 3c47879..95bd7be 100644
43 --- a/src/rsn_supp/wpa.c
44 +++ b/src/rsn_supp/wpa.c
45 @@ -714,6 +714,15 @@ static int wpa_supplicant_install_gtk(struct wpa_sm *sm,
46 const u8 *_gtk = gd->gtk;
47 u8 gtk_buf[32];
48
49 + /* Detect possible key reinstallation */
50 + if (sm->gtk.gtk_len == (size_t) gd->gtk_len &&
51 + os_memcmp(sm->gtk.gtk, gd->gtk, sm->gtk.gtk_len) == 0) {
52 + wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
53 + "WPA: Not reinstalling already in-use GTK to the driver (keyidx=%d tx=%d len=%d)",
54 + gd->keyidx, gd->tx, gd->gtk_len);
55 + return 0;
56 + }
57 +
58 wpa_hexdump_key(MSG_DEBUG, "WPA: Group Key", gd->gtk, gd->gtk_len);
59 wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
60 "WPA: Installing GTK to the driver (keyidx=%d tx=%d len=%d)",
61 @@ -748,6 +757,9 @@ static int wpa_supplicant_install_gtk(struct wpa_sm *sm,
62 }
63 os_memset(gtk_buf, 0, sizeof(gtk_buf));
64
65 + sm->gtk.gtk_len = gd->gtk_len;
66 + os_memcpy(sm->gtk.gtk, gd->gtk, sm->gtk.gtk_len);
67 +
68 return 0;
69 }
70
71 @@ -854,6 +866,48 @@ static int wpa_supplicant_pairwise_gtk(struct wpa_sm *sm,
72 }
73
74
75 +#ifdef CONFIG_IEEE80211W
76 +static int wpa_supplicant_install_igtk(struct wpa_sm *sm,
77 + const struct wpa_igtk_kde *igtk)
78 +{
79 + size_t len = wpa_cipher_key_len(sm->mgmt_group_cipher);
80 + u16 keyidx = WPA_GET_LE16(igtk->keyid);
81 +
82 + /* Detect possible key reinstallation */
83 + if (sm->igtk.igtk_len == len &&
84 + os_memcmp(sm->igtk.igtk, igtk->igtk, sm->igtk.igtk_len) == 0) {
85 + wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
86 + "WPA: Not reinstalling already in-use IGTK to the driver (keyidx=%d)",
87 + keyidx);
88 + return 0;
89 + }
90 +
91 + wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
92 + "WPA: IGTK keyid %d pn %02x%02x%02x%02x%02x%02x",
93 + keyidx, MAC2STR(igtk->pn));
94 + wpa_hexdump_key(MSG_DEBUG, "WPA: IGTK", igtk->igtk, len);
95 + if (keyidx > 4095) {
96 + wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
97 + "WPA: Invalid IGTK KeyID %d", keyidx);
98 + return -1;
99 + }
100 + if (wpa_sm_set_key(sm, wpa_cipher_to_alg(sm->mgmt_group_cipher),
101 + broadcast_ether_addr,
102 + keyidx, 0, igtk->pn, sizeof(igtk->pn),
103 + igtk->igtk, len) < 0) {
104 + wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
105 + "WPA: Failed to configure IGTK to the driver");
106 + return -1;
107 + }
108 +
109 + sm->igtk.igtk_len = len;
110 + os_memcpy(sm->igtk.igtk, igtk->igtk, sm->igtk.igtk_len);
111 +
112 + return 0;
113 +}
114 +#endif /* CONFIG_IEEE80211W */
115 +
116 +
117 static int ieee80211w_set_keys(struct wpa_sm *sm,
118 struct wpa_eapol_ie_parse *ie)
119 {
120 @@ -864,30 +918,14 @@ static int ieee80211w_set_keys(struct wpa_sm *sm,
121 if (ie->igtk) {
122 size_t len;
123 const struct wpa_igtk_kde *igtk;
124 - u16 keyidx;
125 +
126 len = wpa_cipher_key_len(sm->mgmt_group_cipher);
127 if (ie->igtk_len != WPA_IGTK_KDE_PREFIX_LEN + len)
128 return -1;
129 +
130 igtk = (const struct wpa_igtk_kde *) ie->igtk;
131 - keyidx = WPA_GET_LE16(igtk->keyid);
132 - wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG, "WPA: IGTK keyid %d "
133 - "pn %02x%02x%02x%02x%02x%02x",
134 - keyidx, MAC2STR(igtk->pn));
135 - wpa_hexdump_key(MSG_DEBUG, "WPA: IGTK",
136 - igtk->igtk, len);
137 - if (keyidx > 4095) {
138 - wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
139 - "WPA: Invalid IGTK KeyID %d", keyidx);
140 - return -1;
141 - }
142 - if (wpa_sm_set_key(sm, wpa_cipher_to_alg(sm->mgmt_group_cipher),
143 - broadcast_ether_addr,
144 - keyidx, 0, igtk->pn, sizeof(igtk->pn),
145 - igtk->igtk, len) < 0) {
146 - wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
147 - "WPA: Failed to configure IGTK to the driver");
148 + if (wpa_supplicant_install_igtk(sm, igtk) < 0)
149 return -1;
150 - }
151 }
152
153 return 0;
154 @@ -2307,7 +2345,7 @@ void wpa_sm_deinit(struct wpa_sm *sm)
155 */
156 void wpa_sm_notify_assoc(struct wpa_sm *sm, const u8 *bssid)
157 {
158 - int clear_ptk = 1;
159 + int clear_keys = 1;
160
161 if (sm == NULL)
162 return;
163 @@ -2333,11 +2371,11 @@ void wpa_sm_notify_assoc(struct wpa_sm *sm, const u8 *bssid)
164 /* Prepare for the next transition */
165 wpa_ft_prepare_auth_request(sm, NULL);
166
167 - clear_ptk = 0;
168 + clear_keys = 0;
169 }
170 #endif /* CONFIG_IEEE80211R */
171
172 - if (clear_ptk) {
173 + if (clear_keys) {
174 /*
175 * IEEE 802.11, 8.4.10: Delete PTK SA on (re)association if
176 * this is not part of a Fast BSS Transition.
177 @@ -2347,6 +2385,10 @@ void wpa_sm_notify_assoc(struct wpa_sm *sm, const u8 *bssid)
178 os_memset(&sm->ptk, 0, sizeof(sm->ptk));
179 sm->tptk_set = 0;
180 os_memset(&sm->tptk, 0, sizeof(sm->tptk));
181 + os_memset(&sm->gtk, 0, sizeof(sm->gtk));
182 +#ifdef CONFIG_IEEE80211W
183 + os_memset(&sm->igtk, 0, sizeof(sm->igtk));
184 +#endif /* CONFIG_IEEE80211W */
185 }
186
187 #ifdef CONFIG_TDLS
188 @@ -2877,6 +2919,10 @@ void wpa_sm_drop_sa(struct wpa_sm *sm)
189 os_memset(sm->pmk, 0, sizeof(sm->pmk));
190 os_memset(&sm->ptk, 0, sizeof(sm->ptk));
191 os_memset(&sm->tptk, 0, sizeof(sm->tptk));
192 + os_memset(&sm->gtk, 0, sizeof(sm->gtk));
193 +#ifdef CONFIG_IEEE80211W
194 + os_memset(&sm->igtk, 0, sizeof(sm->igtk));
195 +#endif /* CONFIG_IEEE80211W */
196 #ifdef CONFIG_IEEE80211R
197 os_memset(sm->xxkey, 0, sizeof(sm->xxkey));
198 os_memset(sm->pmk_r0, 0, sizeof(sm->pmk_r0));
199 @@ -2949,29 +2995,11 @@ int wpa_wnmsleep_install_key(struct wpa_sm *sm, u8 subelem_id, u8 *buf)
200 os_memset(&gd, 0, sizeof(gd));
201 #ifdef CONFIG_IEEE80211W
202 } else if (subelem_id == WNM_SLEEP_SUBELEM_IGTK) {
203 - struct wpa_igtk_kde igd;
204 - u16 keyidx;
205 -
206 - os_memset(&igd, 0, sizeof(igd));
207 - keylen = wpa_cipher_key_len(sm->mgmt_group_cipher);
208 - os_memcpy(igd.keyid, buf + 2, 2);
209 - os_memcpy(igd.pn, buf + 4, 6);
210 -
211 - keyidx = WPA_GET_LE16(igd.keyid);
212 - os_memcpy(igd.igtk, buf + 10, keylen);
213 -
214 - wpa_hexdump_key(MSG_DEBUG, "Install IGTK (WNM SLEEP)",
215 - igd.igtk, keylen);
216 - if (wpa_sm_set_key(sm, wpa_cipher_to_alg(sm->mgmt_group_cipher),
217 - broadcast_ether_addr,
218 - keyidx, 0, igd.pn, sizeof(igd.pn),
219 - igd.igtk, keylen) < 0) {
220 - wpa_printf(MSG_DEBUG, "Failed to install the IGTK in "
221 - "WNM mode");
222 - os_memset(&igd, 0, sizeof(igd));
223 + const struct wpa_igtk_kde *igtk;
224 +
225 + igtk = (const struct wpa_igtk_kde *) (buf + 2);
226 + if (wpa_supplicant_install_igtk(sm, igtk) < 0)
227 return -1;
228 - }
229 - os_memset(&igd, 0, sizeof(igd));
230 #endif /* CONFIG_IEEE80211W */
231 } else {
232 wpa_printf(MSG_DEBUG, "Unknown element id");
233 diff --git a/src/rsn_supp/wpa_i.h b/src/rsn_supp/wpa_i.h
234 index f653ba6..afc9e37 100644
235 --- a/src/rsn_supp/wpa_i.h
236 +++ b/src/rsn_supp/wpa_i.h
237 @@ -31,6 +31,10 @@ struct wpa_sm {
238 u8 rx_replay_counter[WPA_REPLAY_COUNTER_LEN];
239 int rx_replay_counter_set;
240 u8 request_counter[WPA_REPLAY_COUNTER_LEN];
241 + struct wpa_gtk gtk;
242 +#ifdef CONFIG_IEEE80211W
243 + struct wpa_igtk igtk;
244 +#endif /* CONFIG_IEEE80211W */
245
246 struct eapol_sm *eapol; /* EAPOL state machine from upper level code */
247
248 --
249 2.7.4
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