libeap/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         WPA_PUT_LE16(aad, fc);
  45         pos = aad + 2;
  46         os_memcpy(pos, hdr->addr1, 3 * ETH_ALEN);
  47         pos += 3 * ETH_ALEN;
  48         seq = le_to_host16(hdr->seq_ctrl);
  49         seq &= ~0xfff0; /* Mask Seq#; do not modify Frag# */
  50         WPA_PUT_LE16(pos, seq);
  51         pos += 2;
  52
  53         os_memcpy(pos, hdr + 1, addr4 * ETH_ALEN + qos * 2);
  54         pos += addr4 * ETH_ALEN;
  55         if (qos) {
  56                 pos[0] &= ~0x70;
  57                 if (1 /* FIX: either device has SPP A-MSDU Capab = 0 */)
  58                         pos[0] &= ~0x80;
  59                 pos++;
  60                 *pos++ = 0x00;
  61         }
  62
  63         *aad_len = pos - aad;
  64
  65         os_memcpy(nonce, hdr->addr2, ETH_ALEN);
  66         nonce[6] = data[7]; /* PN5 */
  67         nonce[7] = data[6]; /* PN4 */
  68         nonce[8] = data[5]; /* PN3 */
  69         nonce[9] = data[4]; /* PN2 */
  70         nonce[10] = data[1]; /* PN1 */
  71         nonce[11] = data[0]; /* PN0 */
  72 }
  73
  74
  75 u8 * gcmp_decrypt(const u8 *tk, size_t tk_len, const struct ieee80211_hdr *hdr,
  76                   const u8 *data, size_t data_len, size_t *decrypted_len)
  77 {
  78         u8 aad[30], nonce[12], *plain;
  79         size_t aad_len, mlen;
  80         const u8 *m;
  81
  82         if (data_len < 8 + 16)
  83                 return NULL;
  84
  85         plain = os_malloc(data_len + AES_BLOCK_SIZE);
  86         if (plain == NULL)
  87                 return NULL;
  88
  89         m = data + 8;
  90         mlen = data_len - 8 - 16;
  91
  92         os_memset(aad, 0, sizeof(aad));
  93         gcmp_aad_nonce(hdr, data, aad, &aad_len, nonce);
  94         wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
  95         wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
  96
  97         if (aes_gcm_ad(tk, tk_len, nonce, sizeof(nonce), m, mlen, aad, aad_len,
  98                        m + mlen, plain) < 0) {
  99                 u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
 100                 wpa_printf(MSG_INFO, "Invalid GCMP frame: A1=" MACSTR
 101                            " A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
 102                            MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
 103                            MAC2STR(hdr->addr3),
 104                            WLAN_GET_SEQ_SEQ(seq_ctrl),
 105                            WLAN_GET_SEQ_FRAG(seq_ctrl));
 106                 os_free(plain);
 107                 return NULL;
 108         }
 109
 110         *decrypted_len = mlen;
 111         return plain;
 112 }
 113
 114
 115 u8 * gcmp_encrypt(const u8 *tk, size_t tk_len, const u8 *frame, size_t len,
 116                   size_t hdrlen, const u8 *qos,
 117                   const u8 *pn, int keyid, size_t *encrypted_len)
 118 {
 119         u8 aad[30], nonce[12], *crypt, *pos;
 120         size_t aad_len, plen;
 121         struct ieee80211_hdr *hdr;
 122
 123         if (len < hdrlen || hdrlen < 24)
 124                 return NULL;
 125         plen = len - hdrlen;
 126
 127         crypt = os_malloc(hdrlen + 8 + plen + 16 + AES_BLOCK_SIZE);
 128         if (crypt == NULL)
 129                 return NULL;
 130
 131         os_memcpy(crypt, frame, hdrlen);
 132         hdr = (struct ieee80211_hdr *) crypt;
 133         pos = crypt + hdrlen;
 134         *pos++ = pn[5]; /* PN0 */
 135         *pos++ = pn[4]; /* PN1 */
 136         *pos++ = 0x00; /* Rsvd */
 137         *pos++ = 0x20 | (keyid << 6);
 138         *pos++ = pn[3]; /* PN2 */
 139         *pos++ = pn[2]; /* PN3 */
 140         *pos++ = pn[1]; /* PN4 */
 141         *pos++ = pn[0]; /* PN5 */
 142
 143         os_memset(aad, 0, sizeof(aad));
 144         gcmp_aad_nonce(hdr, crypt + hdrlen, aad, &aad_len, nonce);
 145         wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
 146         wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
 147
 148         if (aes_gcm_ae(tk, tk_len, nonce, sizeof(nonce), frame + hdrlen, plen,
 149                        aad, aad_len, pos, pos + plen) < 0) {
 150                 os_free(crypt);
 151                 return NULL;
 152         }
 153
 154         wpa_hexdump(MSG_EXCESSIVE, "GCMP MIC", pos + plen, 16);
 155         wpa_hexdump(MSG_EXCESSIVE, "GCMP encrypted", pos, plen);
 156
 157         *encrypted_len = hdrlen + 8 + plen + 16;
 158
 159         return crypt;
 160 }