hostap/wlantest/gcmp.c

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/*
* GCM with GMAC Protocol (GCMP)
* Copyright (c) 2012, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "utils/includes.h"
#include "utils/common.h"
#include "common/ieee802_11_defs.h"
#include "crypto/aes.h"
#include "crypto/aes_wrap.h"
#include "wlantest.h"
static void gcmp_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;
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_HTC;
qc = (const u8 *) (hdr + 1);
if (addr4)
qc += ETH_ALEN;
}
}
fc &= ~(WLAN_FC_RETRY | WLAN_FC_PWRMGT | WLAN_FC_MOREDATA);
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, hdr->addr2, ETH_ALEN);
nonce[6] = data[7]; /* PN5 */
nonce[7] = data[6]; /* PN4 */
nonce[8] = data[5]; /* PN3 */
nonce[9] = data[4]; /* PN2 */
nonce[10] = data[1]; /* PN1 */
nonce[11] = data[0]; /* PN0 */
}
u8 * gcmp_decrypt(const u8 *tk, size_t tk_len, const struct ieee80211_hdr *hdr,
const u8 *data, size_t data_len, size_t *decrypted_len)
{
u8 aad[30], nonce[12], *plain;
size_t aad_len, mlen;
const u8 *m;
if (data_len < 8 + 16)
return NULL;
plain = os_malloc(data_len + AES_BLOCK_SIZE);
if (plain == NULL)
return NULL;
m = data + 8;
mlen = data_len - 8 - 16;
os_memset(aad, 0, sizeof(aad));
gcmp_aad_nonce(hdr, data, aad, &aad_len, nonce);
wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
if (aes_gcm_ad(tk, tk_len, nonce, sizeof(nonce), m, mlen, aad, aad_len,
m + mlen, plain) < 0) {
u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
wpa_printf(MSG_INFO, "Invalid GCMP frame: A1=" MACSTR
" A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
MAC2STR(hdr->addr3),
WLAN_GET_SEQ_SEQ(seq_ctrl),
WLAN_GET_SEQ_FRAG(seq_ctrl));
os_free(plain);
return NULL;
}
*decrypted_len = mlen;
return plain;
}
u8 * gcmp_encrypt(const u8 *tk, size_t tk_len, const u8 *frame, size_t len,
size_t hdrlen, const u8 *qos,
const u8 *pn, int keyid, size_t *encrypted_len)
{
u8 aad[30], nonce[12], *crypt, *pos;
size_t aad_len, plen;
struct ieee80211_hdr *hdr;
if (len < hdrlen || hdrlen < 24)
return NULL;
plen = len - hdrlen;
crypt = os_malloc(hdrlen + 8 + plen + 16 + AES_BLOCK_SIZE);
if (crypt == NULL)
return NULL;
os_memcpy(crypt, frame, hdrlen);
hdr = (struct ieee80211_hdr *) crypt;
pos = crypt + hdrlen;
*pos++ = pn[5]; /* PN0 */
*pos++ = pn[4]; /* PN1 */
*pos++ = 0x00; /* Rsvd */
*pos++ = 0x20 | (keyid << 6);
*pos++ = pn[3]; /* PN2 */
*pos++ = pn[2]; /* PN3 */
*pos++ = pn[1]; /* PN4 */
*pos++ = pn[0]; /* PN5 */
os_memset(aad, 0, sizeof(aad));
gcmp_aad_nonce(hdr, crypt + hdrlen, aad, &aad_len, nonce);
wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
if (aes_gcm_ae(tk, tk_len, nonce, sizeof(nonce), frame + hdrlen, plen,
aad, aad_len, pos, pos + plen) < 0) {
os_free(crypt);
return NULL;
}
wpa_hexdump(MSG_EXCESSIVE, "GCMP MIC", pos + plen, 16);
wpa_hexdump(MSG_EXCESSIVE, "GCMP encrypted", pos, plen);
*encrypted_len = hdrlen + 8 + plen + 16;
return crypt;
}