wlantest/gcmp.c

   1 /*
   2  * GCM with GMAC Protocol (GCMP)
   3  * Copyright (c) 2012, Jouni Malinen <j@w1.fi>
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "utils/includes.h"
  10
  11 #include "utils/common.h"
  12 #include "common/ieee802_11_defs.h"
  13 #include "crypto/aes.h"
  14 #include "crypto/aes_wrap.h"
  15 #include "wlantest.h"
  16
  17
  18 static void gcmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
  19                            u8 *aad, size_t *aad_len, u8 *nonce)
  20 {
  21         u16 fc, stype, seq;
  22         int qos = 0, addr4 = 0;
  23         u8 *pos;
  24
  25         fc = le_to_host16(hdr->frame_control);
  26         stype = WLAN_FC_GET_STYPE(fc);
  27         if ((fc & (WLAN_FC_TODS | WLAN_FC_FROMDS)) ==
  28             (WLAN_FC_TODS | WLAN_FC_FROMDS))
  29                 addr4 = 1;
  30
  31         if (WLAN_FC_GET_TYPE(fc) == WLAN_FC_TYPE_DATA) {
  32                 fc &= ~0x0070; /* Mask subtype bits */
  33                 if (stype & 0x08) {
  34                         const u8 *qc;
  35                         qos = 1;
  36                         fc &= ~WLAN_FC_ORDER;
  37                         qc = (const u8 *) (hdr + 1);
  38                         if (addr4)
  39                                 qc += ETH_ALEN;
  40                 }
  41         }
  42
  43         fc &= ~(WLAN_FC_RETRY | WLAN_FC_PWRMGT | WLAN_FC_MOREDATA);
  44         fc |= WLAN_FC_ISWEP;
  45         WPA_PUT_LE16(aad, fc);
  46         pos = aad + 2;
  47         os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
  48         pos += 3 * ETH_ALEN;
  49         seq = le_to_host16(hdr->seq_ctrl);
  50         seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
  51         WPA_PUT_LE16(pos, seq);
  52         pos += 2;
  53
  54         os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
  55         pos += addr4 * ETH_ALEN;
  56         if (qos) {
  57                 pos[0] &= ~0x70;
  58                 if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
  59                         pos[0] &= ~0x80;
  60                 pos++;
  61                 *pos++ = 0x00;
  62         }
  63
  64         *aad_len = pos - aad;
  65
  66         os_memcpy(nonce, hdr->addr2, ETH_ALEN);
  67         nonce[6] = data[7]; /* PN5 */
  68         nonce[7] = data[6]; /* PN4 */
  69         nonce[8] = data[5]; /* PN3 */
  70         nonce[9] = data[4]; /* PN2 */
  71         nonce[10] = data[1]; /* PN1 */
  72         nonce[11] = data[0]; /* PN0 */
  73 }
  74
  75
  76 u8 * gcmp_decrypt(const u8 *tk, size_t tk_len, const struct ieee80211_hdr *hdr,
  77                   const u8 *data, size_t data_len, size_t *decrypted_len)
  78 {
  79         u8 aad[30], nonce[12], *plain;
  80         size_t aad_len, mlen;
  81         const u8 *m;
  82
  83         if (data_len < 8 + 16)
  84                 return NULL;
  85
  86         plain = os_malloc(data_len + AES_BLOCK_SIZE);
  87         if (plain == NULL)
  88                 return NULL;
  89
  90         m = data + 8;
  91         mlen = data_len - 8 - 16;
  92
  93         os_memset(aad, 0, sizeof(aad));
  94         gcmp_aad_nonce(hdr, data, aad, &aad_len, nonce);
  95         wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
  96         wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
  97
  98         if (aes_gcm_ad(tk, tk_len, nonce, sizeof(nonce), m, mlen, aad, aad_len,
  99                        m + mlen, plain) < 0) {
 100                 u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
 101                 wpa_printf(MSG_INFO, "Invalid GCMP frame: A1=" MACSTR
 102                            " A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
 103                            MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
 104                            MAC2STR(hdr->addr3),
 105                            WLAN_GET_SEQ_SEQ(seq_ctrl),
 106                            WLAN_GET_SEQ_FRAG(seq_ctrl));
 107                 os_free(plain);
 108                 return NULL;
 109         }
 110
 111         *decrypted_len = mlen;
 112         return plain;
 113 }
 114
 115
 116 u8 * gcmp_encrypt(const u8 *tk, size_t tk_len, u8 *frame, size_t len,
 117                   size_t hdrlen, u8 *qos,
 118                   u8 *pn, int keyid, size_t *encrypted_len)
 119 {
 120         u8 aad[30], nonce[12], *crypt, *pos;
 121         size_t aad_len, plen;
 122         struct ieee80211_hdr *hdr;
 123
 124         if (len < hdrlen || hdrlen < 24)
 125                 return NULL;
 126         plen = len - hdrlen;
 127
 128         crypt = os_malloc(hdrlen + 8 + plen + 16 + AES_BLOCK_SIZE);
 129         if (crypt == NULL)
 130                 return NULL;
 131
 132         os_memcpy(crypt, frame, hdrlen);
 133         hdr = (struct ieee80211_hdr *) crypt;
 134         hdr->frame_control |= host_to_le16(WLAN_FC_ISWEP);
 135         pos = crypt + hdrlen;
 136         *pos++ = pn[5]; /* PN0 */
 137         *pos++ = pn[4]; /* PN1 */
 138         *pos++ = 0x00; /* Rsvd */
 139         *pos++ = 0x20 | (keyid << 6);
 140         *pos++ = pn[3]; /* PN2 */
 141         *pos++ = pn[2]; /* PN3 */
 142         *pos++ = pn[1]; /* PN4 */
 143         *pos++ = pn[0]; /* PN5 */
 144
 145         os_memset(aad, 0, sizeof(aad));
 146         gcmp_aad_nonce(hdr, crypt + hdrlen, aad, &aad_len, nonce);
 147         wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
 148         wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
 149
 150         if (aes_gcm_ae(tk, tk_len, nonce, sizeof(nonce), frame + hdrlen, plen,
 151                        aad, aad_len, pos, pos + plen) < 0) {
 152                 os_free(crypt);
 153                 return NULL;
 154         }
 155
 156         wpa_hexdump(MSG_EXCESSIVE, "GCMP MIC", pos + plen, 16);
 157         wpa_hexdump(MSG_EXCESSIVE, "GCMP encrypted", pos, plen);
 158
 159         *encrypted_len = hdrlen + 8 + plen + 16;
 160
 161         return crypt;
 162 }