--- /dev/null
+/*
+ * CTR with CBC-MAC Protocol (CCMP)
+ * Copyright (c) 2010, Jouni Malinen <j@w1.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Alternatively, this software may be distributed under the terms of BSD
+ * license.
+ *
+ * See README and COPYING for more details.
+ */
+
+#include "utils/includes.h"
+
+#include "utils/common.h"
+#include "common/ieee802_11_defs.h"
+#include "crypto/aes.h"
+#include "wlantest.h"
+
+
+static void ccmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
+ u8 *aad, size_t *aad_len, u8 *nonce)
+{
+ u16 fc, stype, seq;
+ int qos = 0, addr4 = 0;
+ u8 *pos;
+
+ nonce[0] = 0;
+
+ fc = le_to_host16(hdr->frame_control);
+ stype = WLAN_FC_GET_STYPE(fc);
+ if ((fc & (WLAN_FC_TODS | WLAN_FC_FROMDS)) ==
+ (WLAN_FC_TODS | WLAN_FC_FROMDS))
+ addr4 = 1;
+
+ if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA) {
+ fc &= ~0x0070; /* Mask subtype bits */
+ if (stype & 0x08) {
+ const u8 *qc;
+ qos = 1;
+ fc &= ~WLAN_FC_ORDER;
+ qc = (const u8 *) (hdr + 1);
+ if (addr4)
+ qc += ETH_ALEN;
+ nonce[0] = qc[0] & 0x0f;
+ }
+ } else if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_MGMT)
+ nonce[0] |= 0x10; /* Management */
+
+ fc &= ~(WLAN_FC_RETRY | WLAN_FC_PWRMGT | WLAN_FC_MOREDATA);
+ fc |= WLAN_FC_ISWEP;
+ WPA_PUT_LE16(aad, fc);
+ pos = aad + 2;
+ os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
+ pos += 3 * ETH_ALEN;
+ seq = le_to_host16(hdr->seq_ctrl);
+ seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
+ WPA_PUT_LE16(pos, seq);
+ pos += 2;
+
+ os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
+ pos += addr4 * ETH_ALEN;
+ if (qos) {
+ pos[0] &= 0x70;
+ if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
+ pos[0] &= 0x80;
+ pos++;
+ *pos++ = 0x00;
+ }
+
+ *aad_len = pos - aad;
+
+ os_memcpy(nonce + 1, hdr->addr2, ETH_ALEN);
+ nonce[7] = data[7]; /* PN5 */
+ nonce[8] = data[6]; /* PN4 */
+ nonce[9] = data[5]; /* PN3 */
+ nonce[10] = data[4]; /* PN2 */
+ nonce[11] = data[1]; /* PN1 */
+ nonce[12] = data[0]; /* PN0 */
+}
+
+
+static void xor_aes_block(u8 *dst, const u8 *src)
+{
+ u32 *d = (u32 *) dst;
+ u32 *s = (u32 *) src;
+ *d++ ^= *s++;
+ *d++ ^= *s++;
+ *d++ ^= *s++;
+ *d++ ^= *s++;
+}
+
+
+u8 * ccmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
+ const u8 *data, size_t data_len, size_t *decrypted_len)
+{
+ u8 aad[2 + 30], nonce[13];
+ size_t aad_len;
+ u8 b[AES_BLOCK_SIZE], x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
+ void *aes;
+ const u8 *m, *mpos, *mic;
+ size_t mlen, last;
+ int i;
+ u8 *plain, *ppos;
+ u8 t[8];
+
+ if (data_len < 8 + 8)
+ return NULL;
+
+ plain = os_malloc(data_len);
+ if (plain == NULL)
+ return NULL;
+
+ aes = aes_encrypt_init(tk, 16);
+ if (aes == NULL) {
+ os_free(plain);
+ return NULL;
+ }
+
+ m = data + 8;
+ mlen = data_len - 8 - 8;
+ last = mlen % AES_BLOCK_SIZE;
+
+ os_memset(aad, 0, sizeof(aad));
+ ccmp_aad_nonce(hdr, data, &aad[2], &aad_len, nonce);
+ WPA_PUT_BE16(aad, aad_len);
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP AAD", &aad[2], aad_len);
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP nonce", nonce, 13);
+
+ /* CCM: M=8 L=2, Adata=1, M' = (M-2)/2 = 3, L' = L-1 = 1 */
+
+ /* A_i = Flags | Nonce N | Counter i */
+ a[0] = 0x01; /* Flags = L' */
+ os_memcpy(&a[1], nonce, 13);
+
+ /* Decryption */
+
+ mic = data + data_len - 8;
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP U", mic, 8);
+ /* U = T XOR S_0; S_0 = E(K, A_0) */
+ WPA_PUT_BE16(&a[14], 0);
+ aes_encrypt(aes, a, x);
+ for (i = 0; i < 8; i++)
+ t[i] = mic[i] ^ x[i];
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP T", t, 8);
+
+ /* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */
+ ppos = plain;
+ mpos = m;
+ for (i = 1; i <= mlen / AES_BLOCK_SIZE; i++) {
+ WPA_PUT_BE16(&a[14], i);
+ /* S_i = E(K, A_i) */
+ aes_encrypt(aes, a, ppos);
+ xor_aes_block(ppos, mpos);
+ ppos += AES_BLOCK_SIZE;
+ mpos += AES_BLOCK_SIZE;
+ }
+ if (last) {
+ WPA_PUT_BE16(&a[14], i);
+ aes_encrypt(aes, a, ppos);
+ /* XOR zero-padded last block */
+ for (i = 0; i < last; i++)
+ *ppos++ ^= *mpos++;
+ }
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP decrypted", plain, mlen);
+
+ /* Authentication */
+ /* B_0: Flags | Nonce N | l(m) */
+ b[0] = 0x40 /* Adata */ | (3 /* M' */ << 3) | 1 /* L' */;
+ os_memcpy(&b[1], nonce, 13);
+ WPA_PUT_BE16(&b[14], mlen);
+
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP B_0", b, AES_BLOCK_SIZE);
+ aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */
+
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP B_1", aad, AES_BLOCK_SIZE);
+ xor_aes_block(aad, x);
+ aes_encrypt(aes, aad, x); /* X_2 = E(K, X_1 XOR B_1) */
+
+ wpa_hexdump(MSG_EXCESSIVE, "CCMP B_2", &aad[AES_BLOCK_SIZE],
+ AES_BLOCK_SIZE);
+ xor_aes_block(&aad[AES_BLOCK_SIZE], x);
+ aes_encrypt(aes, &aad[AES_BLOCK_SIZE], x); /* X_3 = E(K, X_2 XOR B_2)
+ */
+
+ ppos = plain;
+ for (i = 0; i < mlen / AES_BLOCK_SIZE; i++) {
+ /* X_i+1 = E(K, X_i XOR B_i) */
+ xor_aes_block(x, ppos);
+ ppos += AES_BLOCK_SIZE;
+ aes_encrypt(aes, x, x);
+ }
+ if (last) {
+ /* XOR zero-padded last block */
+ for (i = 0; i < last; i++)
+ x[i] ^= *ppos++;
+ aes_encrypt(aes, x, x);
+ }
+
+ aes_encrypt_deinit(aes);
+
+ if (os_memcmp(x, t, 8) != 0) {
+ wpa_printf(MSG_INFO, "Invalid CCMP MIC in frame from " MACSTR,
+ MAC2STR(hdr->addr2));
+ os_free(plain);
+ return NULL;
+ }
+
+ *decrypted_len = mlen;
+ return plain;
+}
}
+static void rx_data_bss_prot_group(struct wlantest *wt,
+ const struct ieee80211_hdr *hdr,
+ const u8 *qos, const u8 *dst, const u8 *src,
+ const u8 *data, size_t len)
+{
+ struct wlantest_bss *bss;
+ int keyid;
+
+ bss = bss_get(wt, hdr->addr2);
+ if (bss == NULL)
+ return;
+ if (len < 4) {
+ wpa_printf(MSG_INFO, "Too short group addressed data frame");
+ return;
+ }
+
+ keyid = data[3] >> 6;
+ if (bss->gtk_len[keyid] == 0) {
+ wpa_printf(MSG_MSGDUMP, "No GTK known to decrypt the frame "
+ "(A2=" MACSTR " KeyID=%d)",
+ MAC2STR(hdr->addr2), keyid);
+ return;
+ }
+
+ /* TODO: try to decrypt */
+}
+
+
static void rx_data_bss_prot(struct wlantest *wt,
const struct ieee80211_hdr *hdr, const u8 *qos,
const u8 *dst, const u8 *src, const u8 *data,
size_t len)
{
- /* TODO: Try to decrypt and if success, call rx_data_process() with
- * prot = 1 */
+ struct wlantest_bss *bss;
+ struct wlantest_sta *sta;
+ int keyid;
+ u16 fc = le_to_host16(hdr->frame_control);
+ u8 *decrypted;
+ size_t dlen;
+
+ if (hdr->addr1[0] & 0x01) {
+ rx_data_bss_prot_group(wt, hdr, qos, dst, src, data, len);
+ return;
+ }
+
+ if (fc & WLAN_FC_TODS) {
+ bss = bss_get(wt, hdr->addr1);
+ if (bss == NULL)
+ return;
+ sta = sta_get(bss, hdr->addr2);
+ } else {
+ bss = bss_get(wt, hdr->addr2);
+ if (bss == NULL)
+ return;
+ sta = sta_get(bss, hdr->addr1);
+ }
+ if (sta == NULL || !sta->ptk_set) {
+ wpa_printf(MSG_MSGDUMP, "No PTK known to decrypt the frame");
+ return;
+ }
+
+ if (len < 4) {
+ wpa_printf(MSG_INFO, "Too short encrypted data frame");
+ return;
+ }
+
+ keyid = data[3] >> 6;
+ if (keyid != 0) {
+ wpa_printf(MSG_INFO, "Unexpected non-zero KeyID %d in "
+ "individually addressed Data frame from " MACSTR,
+ keyid, MAC2STR(hdr->addr2));
+ }
+
+ /* TODO: check PN for replay */
+ /* TODO: TKIP */
+
+ decrypted = ccmp_decrypt(sta->ptk.tk1, hdr, data, len, &dlen);
+ if (decrypted)
+ rx_data_process(wt, dst, src, decrypted, dlen, 1);
+ os_free(decrypted);
}
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