wlantest: TKIP frame reassembly for Michael MIC check in fragmented case

Reassemble the full MSDU when processing TKIP protected fragmented
frames so that the Michael MIC can be validated once the last fragment
has been received.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

diff --git a/wlantest/rx_data.c b/wlantest/rx_data.c
index 9e84b8a8e9ce4d53816903982d8c216b1faf2346..16e0f53bc22f3f0493680c7fbd3e7e5af529cad8 100644 (file)
--- a/wlantest/rx_data.c
+++ b/wlantest/rx_data.c
@@ -177,7 +177,8 @@ static u8 * try_ptk(struct wlantest *wt, int pairwise_cipher,
                enum michael_mic_result mic_res;
 
                decrypted = tkip_decrypt(ptk->tk, hdr, data, data_len,
-                                        decrypted_len, &mic_res);
+                                        decrypted_len, &mic_res,
+                                        &wt->tkip_frag);
                if (decrypted && mic_res == MICHAEL_MIC_INCORRECT)
                        add_note(wt, MSG_INFO, "Invalid Michael MIC");
                else if (decrypted && mic_res == MICHAEL_MIC_NOT_VERIFIED)
@@ -328,7 +329,7 @@ skip_replay_det:
                enum michael_mic_result mic_res;
 
                decrypted = tkip_decrypt(bss->gtk[keyid], hdr, data, len,
-                                        &dlen, &mic_res);
+                                        &dlen, &mic_res, &wt->tkip_frag);
                if (decrypted && mic_res == MICHAEL_MIC_INCORRECT)
                        add_note(wt, MSG_INFO, "Invalid Michael MIC");
                else if (decrypted && mic_res == MICHAEL_MIC_NOT_VERIFIED)
@@ -619,7 +620,7 @@ skip_replay_det:
                enum michael_mic_result mic_res;
 
                decrypted = tkip_decrypt(sta->ptk.tk, hdr, data, len, &dlen,
-                                        &mic_res);
+                                        &mic_res, &wt->tkip_frag);
                if (decrypted && mic_res == MICHAEL_MIC_INCORRECT)
                        add_note(wt, MSG_INFO, "Invalid Michael MIC");
                else if (decrypted && mic_res == MICHAEL_MIC_NOT_VERIFIED)

diff --git a/wlantest/test_vectors.c b/wlantest/test_vectors.c
index ca0449d318c50bccc93f89ce828d763e8d3d74ba..7f39c426433b8310a2807196403109f9a850b9fc 100644 (file)
--- a/wlantest/test_vectors.c
+++ b/wlantest/test_vectors.c
@@ -63,7 +63,7 @@ static void test_vector_tkip(void)
 
        wpa_debug_level = MSG_INFO;
        plain = tkip_decrypt(tk, (const struct ieee80211_hdr *) enc,
-                            enc + 24, enc_len - 24, &plain_len, NULL);
+                            enc + 24, enc_len - 24, &plain_len, NULL, NULL);
        wpa_debug_level = MSG_EXCESSIVE;
        os_free(enc);
 

diff --git a/wlantest/tkip.c b/wlantest/tkip.c
index 613a08aa770a615fdbf23e2668b2191ada47cfc9..843f6518a382de0b2c53fef91363a4067d3a1daf 100644 (file)
--- a/wlantest/tkip.c
+++ b/wlantest/tkip.c
@@ -1,5 +1,5 @@
 /*
- * Temporal Key Integrity Protocol (CCMP)
+ * Temporal Key Integrity Protocol (TKIP)
  * Copyright (c) 2010, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
@@ -291,7 +291,7 @@ static void michael_mic_hdr(const struct ieee80211_hdr *hdr11, u8 *hdr)
 
 u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
                  const u8 *data, size_t data_len, size_t *decrypted_len,
-                 enum michael_mic_result *mic_res)
+                 enum michael_mic_result *mic_res, struct tkip_frag *frag)
 {
        u16 iv16;
        u32 iv32;
@@ -304,7 +304,11 @@ u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
        u8 michael_hdr[16];
        u8 mic[8];
        u16 fc = le_to_host16(hdr->frame_control);
+       const u8 *full_payload;
+       size_t full_payload_len;
        u16 sc = le_to_host16(hdr->seq_ctrl);
+       u16 sn;
+       u8 fn;
 
        if (data_len < 8 + 4)
                return NULL;
@@ -337,10 +341,49 @@ u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
        }
        plain_len -= 4;
 
-       /* TODO: MSDU reassembly */
-       if ((fc & WLAN_FC_MOREFRAG) || WLAN_GET_SEQ_FRAG(sc) > 0) {
-               /* For now, return the decrypted fragment and do not check the
-                * Michael MIC value in the last fragment */
+       full_payload = plain;
+       full_payload_len = plain_len;
+
+       sn = WLAN_GET_SEQ_SEQ(sc);
+       fn = WLAN_GET_SEQ_FRAG(sc);
+
+       if (frag) {
+               /* MSDU reassembly for Michael MIC validation */
+               if (fn == 0 && (fc & WLAN_FC_MOREFRAG)) {
+                       /* Start of a new fragmented MSDU */
+                       wpabuf_free(frag->buf);
+                       frag->buf = NULL;
+                       frag->buf = wpabuf_alloc_copy(plain, plain_len);
+                       os_memcpy(frag->ra, hdr->addr1, ETH_ALEN);
+                       os_memcpy(frag->ta, hdr->addr2, ETH_ALEN);
+                       frag->sn = sn;
+                       frag->fn = 0;
+               }
+
+               if (frag->buf && (fn || (fc & WLAN_FC_MOREFRAG)) &&
+                   sn == frag->sn && fn == frag->fn + 1 &&
+                   os_memcmp(frag->ra, hdr->addr1, ETH_ALEN) == 0 &&
+                   os_memcmp(frag->ta, hdr->addr2, ETH_ALEN) == 0) {
+                       /* Add the next fragment */
+                       if (wpabuf_resize(&frag->buf, plain_len) == 0) {
+                               wpabuf_put_data(frag->buf, plain, plain_len);
+                               frag->fn = fn;
+                               if (!(fc & WLAN_FC_MOREFRAG)) {
+                                       full_payload = wpabuf_head(frag->buf);
+                                       full_payload_len =
+                                               wpabuf_len(frag->buf);
+                                       wpa_hexdump(MSG_MSGDUMP,
+                                                   "TKIP reassembled full payload",
+                                                   full_payload,
+                                                   full_payload_len);
+                               }
+                       }
+               }
+       }
+
+       if ((fc & WLAN_FC_MOREFRAG) || (fn > 0 && full_payload == plain)) {
+               /* Return the decrypted fragment and do not check the
+                * Michael MIC value since no reassembled frame is available. */
                *decrypted_len = plain_len;
                if (mic_res) {
                        *mic_res = MICHAEL_MIC_NOT_VERIFIED;
@@ -348,7 +391,7 @@ u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
                }
        }
 
-       if (plain_len < 8) {
+       if (full_payload_len < 8) {
                wpa_printf(MSG_INFO, "TKIP: Not enough room for Michael MIC "
                           "in a frame from " MACSTR, MAC2STR(hdr->addr2));
                os_free(plain);
@@ -357,13 +400,14 @@ u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 
        michael_mic_hdr(hdr, michael_hdr);
        mic_key = tk + ((fc & WLAN_FC_FROMDS) ? 16 : 24);
-       michael_mic(mic_key, michael_hdr, plain, plain_len - 8, mic);
-       if (os_memcmp(mic, plain + plain_len - 8, 8) != 0) {
+       michael_mic(mic_key, michael_hdr, full_payload, full_payload_len - 8,
+                   mic);
+       if (os_memcmp(mic, full_payload + full_payload_len - 8, 8) != 0) {
                wpa_printf(MSG_INFO, "TKIP: Michael MIC mismatch in a frame "
                           "from " MACSTR, MAC2STR(hdr->addr2));
                wpa_hexdump(MSG_DEBUG, "TKIP: Calculated MIC", mic, 8);
                wpa_hexdump(MSG_DEBUG, "TKIP: Received MIC",
-                           plain + plain_len - 8, 8);
+                           full_payload + full_payload_len - 8, 8);
                if (mic_res) {
                        *decrypted_len = plain_len - 8;
                        *mic_res = MICHAEL_MIC_INCORRECT;

diff --git a/wlantest/wlantest.c b/wlantest/wlantest.c
index 62c89e2261502f283b96a1e185cb3795e6a2073d..ac20b068eb8af033afd532a6b7c34a4413d7364d 100644 (file)
--- a/wlantest/wlantest.c
+++ b/wlantest/wlantest.c
@@ -110,6 +110,8 @@ static void wlantest_deinit(struct wlantest *wt)
        clear_notes(wt);
        os_free(wt->decrypted);
        wt->decrypted = NULL;
+       wpabuf_free(wt->tkip_frag.buf);
+       wt->tkip_frag.buf = NULL;
 }
 
 

diff --git a/wlantest/wlantest.h b/wlantest/wlantest.h
index 4ea10c9e8782291383ac31a436e3659a575499fd..33ab42229a542aa76003c6762a4ff667003fe4b6 100644 (file)
--- a/wlantest/wlantest.h
+++ b/wlantest/wlantest.h
@@ -184,6 +184,14 @@ struct wlantest_radius {
 #define MAX_CTRL_CONNECTIONS 10
 #define MAX_NOTES 10
 
+struct tkip_frag {
+       struct wpabuf *buf;
+       u8 ra[ETH_ALEN];
+       u8 ta[ETH_ALEN];
+       u16 sn;
+       u8 fn;
+};
+
 struct wlantest {
        int monitor_sock;
        int monitor_wired;
@@ -227,6 +235,8 @@ struct wlantest {
 
        const char *write_file;
        const char *pcapng_file;
+
+       struct tkip_frag tkip_frag;
 };
 
 void add_note(struct wlantest *wt, int level, const char *fmt, ...)
@@ -311,7 +321,7 @@ enum michael_mic_result {
 };
 u8 * tkip_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
                  const u8 *data, size_t data_len, size_t *decrypted_len,
-                 enum michael_mic_result *mic_res);
+                 enum michael_mic_result *mic_res, struct tkip_frag *frag);
 u8 * tkip_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
                  u8 *pn, int keyid, size_t *encrypted_len);
 void tkip_get_pn(u8 *pn, const u8 *data);