1 // SPDX-License-Identifier: GPL-2.0
2 /* Host AP crypt: host-based CCMP encryption implementation for Host AP driver
4 * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
7 #include <linux/module.h>
8 #include <linux/init.h>
9 #include <linux/slab.h>
10 #include <linux/random.h>
11 #include <linux/skbuff.h>
12 #include <linux/netdevice.h>
13 #include <linux/if_ether.h>
14 #include <linux/if_arp.h>
15 #include <linux/string.h>
16 #include <linux/wireless.h>
19 #include <linux/crypto.h>
20 #include <crypto/aead.h>
22 #include <linux/scatterlist.h>
24 #define AES_BLOCK_LEN 16
25 #define CCMP_HDR_LEN 8
26 #define CCMP_MIC_LEN 8
27 #define CCMP_TK_LEN 16
30 struct rtllib_ccmp_data {
34 u8 tx_pn[CCMP_PN_LEN];
35 u8 rx_pn[CCMP_PN_LEN];
37 u32 dot11RSNAStatsCCMPFormatErrors;
38 u32 dot11RSNAStatsCCMPReplays;
39 u32 dot11RSNAStatsCCMPDecryptErrors;
43 struct crypto_aead *tfm;
45 /* scratch buffers for virt_to_page() (crypto API) */
46 u8 tx_aad[2 * AES_BLOCK_LEN];
47 u8 rx_aad[2 * AES_BLOCK_LEN];
50 static void *rtllib_ccmp_init(int key_idx)
52 struct rtllib_ccmp_data *priv;
54 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
57 priv->key_idx = key_idx;
59 priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC);
60 if (IS_ERR(priv->tfm)) {
61 pr_debug("Could not allocate crypto API aes\n");
70 crypto_free_aead(priv->tfm);
78 static void rtllib_ccmp_deinit(void *priv)
80 struct rtllib_ccmp_data *_priv = priv;
82 if (_priv && _priv->tfm)
83 crypto_free_aead(_priv->tfm);
88 static int ccmp_init_iv_and_aad(struct rtllib_hdr_4addr *hdr,
89 u8 *pn, u8 *iv, u8 *aad)
94 int a4_included, qc_included;
96 fc = le16_to_cpu(hdr->frame_ctl);
97 a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
98 (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
100 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
101 (WLAN_FC_GET_STYPE(fc) & 0x80));
106 pos = (u8 *) &hdr->addr4;
112 /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
113 * mode authentication are not allowed to collide, yet both are derived
114 * from the same vector. We only set L := 1 here to indicate that the
115 * data size can be represented in (L+1) bytes. The CCM layer will take
116 * care of storing the data length in the top (L+1) bytes and setting
117 * and clearing the other bits as is required to derive the two IVs.
121 /* Nonce: QC | A2 | PN */
123 memcpy(iv + 2, hdr->addr2, ETH_ALEN);
124 memcpy(iv + 8, pn, CCMP_PN_LEN);
127 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
129 * SC with bits 4..15 (seq#) masked to zero
134 aad[0] = pos[0] & 0x8f;
135 aad[1] = pos[1] & 0xc7;
136 memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN);
137 pos = (u8 *) &hdr->seq_ctl;
138 aad[20] = pos[0] & 0x0f;
139 aad[21] = 0; /* all bits masked */
140 memset(aad + 22, 0, 8);
142 memcpy(aad + 22, hdr->addr4, ETH_ALEN);
144 aad[a4_included ? 28 : 22] = qc;
145 /* rest of QC masked */
153 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
155 struct rtllib_ccmp_data *key = priv;
158 struct rtllib_hdr_4addr *hdr;
159 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
161 if (skb_headroom(skb) < CCMP_HDR_LEN ||
162 skb_tailroom(skb) < CCMP_MIC_LEN ||
166 pos = skb_push(skb, CCMP_HDR_LEN);
167 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
173 if (key->tx_pn[i] != 0)
178 *pos++ = key->tx_pn[5];
179 *pos++ = key->tx_pn[4];
181 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
182 *pos++ = key->tx_pn[3];
183 *pos++ = key->tx_pn[2];
184 *pos++ = key->tx_pn[1];
185 *pos++ = key->tx_pn[0];
187 hdr = (struct rtllib_hdr_4addr *) skb->data;
188 if (!tcb_desc->bHwSec) {
189 struct aead_request *req;
190 struct scatterlist sg[2];
191 u8 *aad = key->tx_aad;
192 u8 iv[AES_BLOCK_LEN];
194 int data_len = skb->len - hdr_len - CCMP_HDR_LEN;
196 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
200 aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
202 skb_put(skb, CCMP_MIC_LEN);
203 sg_init_table(sg, 2);
204 sg_set_buf(&sg[0], aad, aad_len);
205 sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
206 data_len + CCMP_MIC_LEN);
208 aead_request_set_callback(req, 0, NULL, NULL);
209 aead_request_set_ad(req, aad_len);
210 aead_request_set_crypt(req, sg, sg, data_len, iv);
212 ret = crypto_aead_encrypt(req);
213 aead_request_free(req);
222 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
224 struct rtllib_ccmp_data *key = priv;
226 struct rtllib_hdr_4addr *hdr;
227 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
231 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
232 key->dot11RSNAStatsCCMPFormatErrors++;
236 hdr = (struct rtllib_hdr_4addr *) skb->data;
237 pos = skb->data + hdr_len;
239 if (!(keyidx & (1 << 5))) {
240 if (net_ratelimit()) {
241 pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
244 key->dot11RSNAStatsCCMPFormatErrors++;
248 if (key->key_idx != keyidx) {
249 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
250 key->key_idx, keyidx, priv);
254 if (net_ratelimit()) {
255 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
268 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
269 key->dot11RSNAStatsCCMPReplays++;
272 if (!tcb_desc->bHwSec) {
273 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
274 struct aead_request *req;
275 struct scatterlist sg[2];
276 u8 *aad = key->rx_aad;
277 u8 iv[AES_BLOCK_LEN];
280 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
284 aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
286 sg_init_table(sg, 2);
287 sg_set_buf(&sg[0], aad, aad_len);
288 sg_set_buf(&sg[1], pos, data_len);
290 aead_request_set_callback(req, 0, NULL, NULL);
291 aead_request_set_ad(req, aad_len);
292 aead_request_set_crypt(req, sg, sg, data_len, iv);
294 ret = crypto_aead_decrypt(req);
295 aead_request_free(req);
298 if (net_ratelimit()) {
299 pr_debug("CCMP: decrypt failed: STA= %pM\n",
302 key->dot11RSNAStatsCCMPDecryptErrors++;
306 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
308 /* Remove hdr and MIC */
309 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
310 skb_pull(skb, CCMP_HDR_LEN);
311 skb_trim(skb, skb->len - CCMP_MIC_LEN);
317 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
319 struct rtllib_ccmp_data *data = priv;
321 struct crypto_aead *tfm = data->tfm;
323 keyidx = data->key_idx;
324 memset(data, 0, sizeof(*data));
325 data->key_idx = keyidx;
327 if (len == CCMP_TK_LEN) {
328 memcpy(data->key, key, CCMP_TK_LEN);
331 data->rx_pn[0] = seq[5];
332 data->rx_pn[1] = seq[4];
333 data->rx_pn[2] = seq[3];
334 data->rx_pn[3] = seq[2];
335 data->rx_pn[4] = seq[1];
336 data->rx_pn[5] = seq[0];
338 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
339 crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
341 } else if (len == 0) {
351 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
353 struct rtllib_ccmp_data *data = priv;
355 if (len < CCMP_TK_LEN)
360 memcpy(key, data->key, CCMP_TK_LEN);
363 seq[0] = data->tx_pn[5];
364 seq[1] = data->tx_pn[4];
365 seq[2] = data->tx_pn[3];
366 seq[3] = data->tx_pn[2];
367 seq[4] = data->tx_pn[1];
368 seq[5] = data->tx_pn[0];
375 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
377 struct rtllib_ccmp_data *ccmp = priv;
380 "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n",
381 ccmp->key_idx, ccmp->key_set,
382 ccmp->tx_pn, ccmp->rx_pn,
383 ccmp->dot11RSNAStatsCCMPFormatErrors,
384 ccmp->dot11RSNAStatsCCMPReplays,
385 ccmp->dot11RSNAStatsCCMPDecryptErrors);
388 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
390 .init = rtllib_ccmp_init,
391 .deinit = rtllib_ccmp_deinit,
392 .encrypt_mpdu = rtllib_ccmp_encrypt,
393 .decrypt_mpdu = rtllib_ccmp_decrypt,
394 .encrypt_msdu = NULL,
395 .decrypt_msdu = NULL,
396 .set_key = rtllib_ccmp_set_key,
397 .get_key = rtllib_ccmp_get_key,
398 .print_stats = rtllib_ccmp_print_stats,
399 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
400 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
401 .owner = THIS_MODULE,
405 static int __init rtllib_crypto_ccmp_init(void)
407 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
411 static void __exit rtllib_crypto_ccmp_exit(void)
413 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
416 module_init(rtllib_crypto_ccmp_init);
417 module_exit(rtllib_crypto_ccmp_exit);
419 MODULE_LICENSE("GPL");