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
gcmp_aad_nonce(const struct ieee80211_hdr * hdr,const u8 * data,u8 * aad,size_t * aad_len,u8 * nonce)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_HTC;
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
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)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
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)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 }
161
