1 // SPDX-License-Identifier: GPL-2.0
2 /* Host AP crypt: host-based CCMP encryption implementation for Host AP driver
3 *
4 * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
5 */
6
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>
17 #include "rtllib.h"
18
19 #include <linux/crypto.h>
20 #include <crypto/aead.h>
21
22 #include <linux/scatterlist.h>
23
24 #define AES_BLOCK_LEN 16
25 #define CCMP_HDR_LEN 8
26 #define CCMP_MIC_LEN 8
27 #define CCMP_TK_LEN 16
28 #define CCMP_PN_LEN 6
29
30 struct rtllib_ccmp_data {
31 u8 key[CCMP_TK_LEN];
32 int key_set;
33
34 u8 tx_pn[CCMP_PN_LEN];
35 u8 rx_pn[CCMP_PN_LEN];
36
37 u32 dot11rsna_stats_ccmp_format_errors;
38 u32 dot11rsna_stats_ccmp_replays;
39 u32 dot11rsna_stats_ccmp_decrypt_errors;
40
41 int key_idx;
42
43 struct crypto_aead *tfm;
44
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];
48 };
49
rtllib_ccmp_init(int key_idx)50 static void *rtllib_ccmp_init(int key_idx)
51 {
52 struct rtllib_ccmp_data *priv;
53
54 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
55 if (!priv)
56 goto fail;
57 priv->key_idx = key_idx;
58
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");
62 priv->tfm = NULL;
63 goto fail;
64 }
65 return priv;
66
67 fail:
68 if (priv) {
69 if (priv->tfm)
70 crypto_free_aead(priv->tfm);
71 kfree(priv);
72 }
73
74 return NULL;
75 }
76
rtllib_ccmp_deinit(void * priv)77 static void rtllib_ccmp_deinit(void *priv)
78 {
79 struct rtllib_ccmp_data *_priv = priv;
80
81 if (_priv && _priv->tfm)
82 crypto_free_aead(_priv->tfm);
83 kfree(priv);
84 }
85
ccmp_init_iv_and_aad(struct ieee80211_hdr * hdr,u8 * pn,u8 * iv,u8 * aad)86 static int ccmp_init_iv_and_aad(struct ieee80211_hdr *hdr,
87 u8 *pn, u8 *iv, u8 *aad)
88 {
89 u8 *pos, qc = 0;
90 size_t aad_len;
91 u16 fc;
92 int a4_included, qc_included;
93
94 fc = le16_to_cpu(hdr->frame_control);
95 a4_included = ieee80211_has_a4(hdr->frame_control);
96
97 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
98 (WLAN_FC_GET_STYPE(fc) & 0x80));
99 aad_len = 22;
100 if (a4_included)
101 aad_len += 6;
102 if (qc_included) {
103 pos = (u8 *)&hdr->addr4;
104 if (a4_included)
105 pos += 6;
106 qc = *pos & 0x0f;
107 aad_len += 2;
108 }
109 /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
110 * mode authentication are not allowed to collide, yet both are derived
111 * from the same vector. We only set L := 1 here to indicate that the
112 * data size can be represented in (L+1) bytes. The CCM layer will take
113 * care of storing the data length in the top (L+1) bytes and setting
114 * and clearing the other bits as is required to derive the two IVs.
115 */
116 iv[0] = 0x1;
117
118 /* Nonce: QC | A2 | PN */
119 iv[1] = qc;
120 memcpy(iv + 2, hdr->addr2, ETH_ALEN);
121 memcpy(iv + 8, pn, CCMP_PN_LEN);
122
123 /* AAD:
124 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
125 * A1 | A2 | A3
126 * SC with bits 4..15 (seq#) masked to zero
127 * A4 (if present)
128 * QC (if present)
129 */
130 pos = (u8 *)hdr;
131 aad[0] = pos[0] & 0x8f;
132 aad[1] = pos[1] & 0xc7;
133 memcpy(&aad[2], &hdr->addr1, ETH_ALEN);
134 memcpy(&aad[8], &hdr->addr2, ETH_ALEN);
135 memcpy(&aad[14], &hdr->addr3, ETH_ALEN);
136 pos = (u8 *)&hdr->seq_ctrl;
137 aad[20] = pos[0] & 0x0f;
138 aad[21] = 0; /* all bits masked */
139 memset(aad + 22, 0, 8);
140 if (a4_included)
141 memcpy(aad + 22, hdr->addr4, ETH_ALEN);
142 if (qc_included) {
143 aad[a4_included ? 28 : 22] = qc;
144 /* rest of QC masked */
145 }
146
147 return aad_len;
148 }
149
rtllib_ccmp_encrypt(struct sk_buff * skb,int hdr_len,void * priv)150 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
151 {
152 struct rtllib_ccmp_data *key = priv;
153 int i;
154 u8 *pos;
155 struct ieee80211_hdr *hdr;
156 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
157 MAX_DEV_ADDR_SIZE);
158 if (skb_headroom(skb) < CCMP_HDR_LEN ||
159 skb_tailroom(skb) < CCMP_MIC_LEN ||
160 skb->len < hdr_len)
161 return -1;
162
163 pos = skb_push(skb, CCMP_HDR_LEN);
164 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
165 pos += hdr_len;
166
167 i = CCMP_PN_LEN - 1;
168 while (i >= 0) {
169 key->tx_pn[i]++;
170 if (key->tx_pn[i] != 0)
171 break;
172 i--;
173 }
174
175 *pos++ = key->tx_pn[5];
176 *pos++ = key->tx_pn[4];
177 *pos++ = 0;
178 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
179 *pos++ = key->tx_pn[3];
180 *pos++ = key->tx_pn[2];
181 *pos++ = key->tx_pn[1];
182 *pos++ = key->tx_pn[0];
183
184 hdr = (struct ieee80211_hdr *)skb->data;
185 if (!tcb_desc->bHwSec) {
186 struct aead_request *req;
187 struct scatterlist sg[2];
188 u8 *aad = key->tx_aad;
189 u8 iv[AES_BLOCK_LEN];
190 int aad_len, ret;
191 int data_len = skb->len - hdr_len - CCMP_HDR_LEN;
192
193 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
194 if (!req)
195 return -ENOMEM;
196
197 aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
198
199 skb_put(skb, CCMP_MIC_LEN);
200 sg_init_table(sg, 2);
201 sg_set_buf(&sg[0], aad, aad_len);
202 sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
203 data_len + CCMP_MIC_LEN);
204
205 aead_request_set_callback(req, 0, NULL, NULL);
206 aead_request_set_ad(req, aad_len);
207 aead_request_set_crypt(req, sg, sg, data_len, iv);
208
209 ret = crypto_aead_encrypt(req);
210 aead_request_free(req);
211
212 return ret;
213 }
214
215 return 0;
216 }
217
rtllib_ccmp_decrypt(struct sk_buff * skb,int hdr_len,void * priv)218 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
219 {
220 struct rtllib_ccmp_data *key = priv;
221 u8 keyidx, *pos;
222 struct ieee80211_hdr *hdr;
223 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
224 MAX_DEV_ADDR_SIZE);
225 u8 pn[6];
226
227 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
228 key->dot11rsna_stats_ccmp_format_errors++;
229 return -1;
230 }
231
232 hdr = (struct ieee80211_hdr *)skb->data;
233 pos = skb->data + hdr_len;
234 keyidx = pos[3];
235 if (!(keyidx & (1 << 5))) {
236 if (net_ratelimit()) {
237 pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
238 hdr->addr2);
239 }
240 key->dot11rsna_stats_ccmp_format_errors++;
241 return -2;
242 }
243 keyidx >>= 6;
244 if (key->key_idx != keyidx) {
245 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
246 key->key_idx, keyidx, priv);
247 return -6;
248 }
249 if (!key->key_set) {
250 if (net_ratelimit()) {
251 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
252 hdr->addr2, keyidx);
253 }
254 return -3;
255 }
256
257 pn[0] = pos[7];
258 pn[1] = pos[6];
259 pn[2] = pos[5];
260 pn[3] = pos[4];
261 pn[4] = pos[1];
262 pn[5] = pos[0];
263 pos += 8;
264 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
265 key->dot11rsna_stats_ccmp_replays++;
266 return -4;
267 }
268 if (!tcb_desc->bHwSec) {
269 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
270 struct aead_request *req;
271 struct scatterlist sg[2];
272 u8 *aad = key->rx_aad;
273 u8 iv[AES_BLOCK_LEN];
274 int aad_len, ret;
275
276 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
277 if (!req)
278 return -ENOMEM;
279
280 aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
281
282 sg_init_table(sg, 2);
283 sg_set_buf(&sg[0], aad, aad_len);
284 sg_set_buf(&sg[1], pos, data_len);
285
286 aead_request_set_callback(req, 0, NULL, NULL);
287 aead_request_set_ad(req, aad_len);
288 aead_request_set_crypt(req, sg, sg, data_len, iv);
289
290 ret = crypto_aead_decrypt(req);
291 aead_request_free(req);
292
293 if (ret) {
294 if (net_ratelimit()) {
295 pr_debug("CCMP: decrypt failed: STA= %pM\n",
296 hdr->addr2);
297 }
298 key->dot11rsna_stats_ccmp_decrypt_errors++;
299 return -5;
300 }
301
302 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
303 }
304 /* Remove hdr and MIC */
305 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
306 skb_pull(skb, CCMP_HDR_LEN);
307 skb_trim(skb, skb->len - CCMP_MIC_LEN);
308
309 return keyidx;
310 }
311
rtllib_ccmp_set_key(void * key,int len,u8 * seq,void * priv)312 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
313 {
314 struct rtllib_ccmp_data *data = priv;
315 int keyidx;
316 struct crypto_aead *tfm = data->tfm;
317
318 keyidx = data->key_idx;
319 memset(data, 0, sizeof(*data));
320 data->key_idx = keyidx;
321 data->tfm = tfm;
322 if (len == CCMP_TK_LEN) {
323 memcpy(data->key, key, CCMP_TK_LEN);
324 data->key_set = 1;
325 if (seq) {
326 data->rx_pn[0] = seq[5];
327 data->rx_pn[1] = seq[4];
328 data->rx_pn[2] = seq[3];
329 data->rx_pn[3] = seq[2];
330 data->rx_pn[4] = seq[1];
331 data->rx_pn[5] = seq[0];
332 }
333 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
334 crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
335 return -1;
336 } else if (len == 0) {
337 data->key_set = 0;
338 } else {
339 return -1;
340 }
341
342 return 0;
343 }
344
rtllib_ccmp_get_key(void * key,int len,u8 * seq,void * priv)345 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
346 {
347 struct rtllib_ccmp_data *data = priv;
348
349 if (len < CCMP_TK_LEN)
350 return -1;
351
352 if (!data->key_set)
353 return 0;
354 memcpy(key, data->key, CCMP_TK_LEN);
355
356 if (seq) {
357 seq[0] = data->tx_pn[5];
358 seq[1] = data->tx_pn[4];
359 seq[2] = data->tx_pn[3];
360 seq[3] = data->tx_pn[2];
361 seq[4] = data->tx_pn[1];
362 seq[5] = data->tx_pn[0];
363 }
364
365 return CCMP_TK_LEN;
366 }
367
rtllib_ccmp_print_stats(struct seq_file * m,void * priv)368 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
369 {
370 struct rtllib_ccmp_data *ccmp = priv;
371
372 seq_printf(m,
373 "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n",
374 ccmp->key_idx, ccmp->key_set,
375 ccmp->tx_pn, ccmp->rx_pn,
376 ccmp->dot11rsna_stats_ccmp_format_errors,
377 ccmp->dot11rsna_stats_ccmp_replays,
378 ccmp->dot11rsna_stats_ccmp_decrypt_errors);
379 }
380
381 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
382 .name = "R-CCMP",
383 .init = rtllib_ccmp_init,
384 .deinit = rtllib_ccmp_deinit,
385 .encrypt_mpdu = rtllib_ccmp_encrypt,
386 .decrypt_mpdu = rtllib_ccmp_decrypt,
387 .encrypt_msdu = NULL,
388 .decrypt_msdu = NULL,
389 .set_key = rtllib_ccmp_set_key,
390 .get_key = rtllib_ccmp_get_key,
391 .print_stats = rtllib_ccmp_print_stats,
392 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
393 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
394 .owner = THIS_MODULE,
395 };
396
rtllib_crypto_ccmp_init(void)397 static int __init rtllib_crypto_ccmp_init(void)
398 {
399 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
400 }
401
rtllib_crypto_ccmp_exit(void)402 static void __exit rtllib_crypto_ccmp_exit(void)
403 {
404 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
405 }
406
407 module_init(rtllib_crypto_ccmp_init);
408 module_exit(rtllib_crypto_ccmp_exit);
409
410 MODULE_LICENSE("GPL");
411