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 dot11RSNAStatsCCMPFormatErrors;
38 u32 dot11RSNAStatsCCMPReplays;
39 u32 dot11RSNAStatsCCMPDecryptErrors;
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 == NULL)
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
77
rtllib_ccmp_deinit(void * priv)78 static void rtllib_ccmp_deinit(void *priv)
79 {
80 struct rtllib_ccmp_data *_priv = priv;
81
82 if (_priv && _priv->tfm)
83 crypto_free_aead(_priv->tfm);
84 kfree(priv);
85 }
86
87
ccmp_init_iv_and_aad(struct rtllib_hdr_4addr * hdr,u8 * pn,u8 * iv,u8 * aad)88 static int ccmp_init_iv_and_aad(struct rtllib_hdr_4addr *hdr,
89 u8 *pn, u8 *iv, u8 *aad)
90 {
91 u8 *pos, qc = 0;
92 size_t aad_len;
93 u16 fc;
94 int a4_included, qc_included;
95
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));
99
100 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
101 (WLAN_FC_GET_STYPE(fc) & 0x80));
102 aad_len = 22;
103 if (a4_included)
104 aad_len += 6;
105 if (qc_included) {
106 pos = (u8 *) &hdr->addr4;
107 if (a4_included)
108 pos += 6;
109 qc = *pos & 0x0f;
110 aad_len += 2;
111 }
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.
118 */
119 iv[0] = 0x1;
120
121 /* Nonce: QC | A2 | PN */
122 iv[1] = qc;
123 memcpy(iv + 2, hdr->addr2, ETH_ALEN);
124 memcpy(iv + 8, pn, CCMP_PN_LEN);
125
126 /* AAD:
127 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
128 * A1 | A2 | A3
129 * SC with bits 4..15 (seq#) masked to zero
130 * A4 (if present)
131 * QC (if present)
132 */
133 pos = (u8 *) hdr;
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);
141 if (a4_included)
142 memcpy(aad + 22, hdr->addr4, ETH_ALEN);
143 if (qc_included) {
144 aad[a4_included ? 28 : 22] = qc;
145 /* rest of QC masked */
146 }
147
148 return aad_len;
149 }
150
151
152
rtllib_ccmp_encrypt(struct sk_buff * skb,int hdr_len,void * priv)153 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
154 {
155 struct rtllib_ccmp_data *key = priv;
156 int i;
157 u8 *pos;
158 struct rtllib_hdr_4addr *hdr;
159 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
160 MAX_DEV_ADDR_SIZE);
161 if (skb_headroom(skb) < CCMP_HDR_LEN ||
162 skb_tailroom(skb) < CCMP_MIC_LEN ||
163 skb->len < hdr_len)
164 return -1;
165
166 pos = skb_push(skb, CCMP_HDR_LEN);
167 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
168 pos += hdr_len;
169
170 i = CCMP_PN_LEN - 1;
171 while (i >= 0) {
172 key->tx_pn[i]++;
173 if (key->tx_pn[i] != 0)
174 break;
175 i--;
176 }
177
178 *pos++ = key->tx_pn[5];
179 *pos++ = key->tx_pn[4];
180 *pos++ = 0;
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];
186
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];
193 int aad_len, ret;
194 int data_len = skb->len - hdr_len - CCMP_HDR_LEN;
195
196 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
197 if (!req)
198 return -ENOMEM;
199
200 aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
201
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);
207
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);
211
212 ret = crypto_aead_encrypt(req);
213 aead_request_free(req);
214
215 return ret;
216 }
217
218 return 0;
219 }
220
221
rtllib_ccmp_decrypt(struct sk_buff * skb,int hdr_len,void * priv)222 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
223 {
224 struct rtllib_ccmp_data *key = priv;
225 u8 keyidx, *pos;
226 struct rtllib_hdr_4addr *hdr;
227 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
228 MAX_DEV_ADDR_SIZE);
229 u8 pn[6];
230
231 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
232 key->dot11RSNAStatsCCMPFormatErrors++;
233 return -1;
234 }
235
236 hdr = (struct rtllib_hdr_4addr *) skb->data;
237 pos = skb->data + hdr_len;
238 keyidx = pos[3];
239 if (!(keyidx & (1 << 5))) {
240 if (net_ratelimit()) {
241 pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
242 hdr->addr2);
243 }
244 key->dot11RSNAStatsCCMPFormatErrors++;
245 return -2;
246 }
247 keyidx >>= 6;
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);
251 return -6;
252 }
253 if (!key->key_set) {
254 if (net_ratelimit()) {
255 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
256 hdr->addr2, keyidx);
257 }
258 return -3;
259 }
260
261 pn[0] = pos[7];
262 pn[1] = pos[6];
263 pn[2] = pos[5];
264 pn[3] = pos[4];
265 pn[4] = pos[1];
266 pn[5] = pos[0];
267 pos += 8;
268 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
269 key->dot11RSNAStatsCCMPReplays++;
270 return -4;
271 }
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];
278 int aad_len, ret;
279
280 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
281 if(!req)
282 return -ENOMEM;
283
284 aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
285
286 sg_init_table(sg, 2);
287 sg_set_buf(&sg[0], aad, aad_len);
288 sg_set_buf(&sg[1], pos, data_len);
289
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);
293
294 ret = crypto_aead_decrypt(req);
295 aead_request_free(req);
296
297 if (ret) {
298 if (net_ratelimit()) {
299 pr_debug("CCMP: decrypt failed: STA= %pM\n",
300 hdr->addr2);
301 }
302 key->dot11RSNAStatsCCMPDecryptErrors++;
303 return -5;
304 }
305
306 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
307 }
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);
312
313 return keyidx;
314 }
315
316
rtllib_ccmp_set_key(void * key,int len,u8 * seq,void * priv)317 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
318 {
319 struct rtllib_ccmp_data *data = priv;
320 int keyidx;
321 struct crypto_aead *tfm = data->tfm;
322
323 keyidx = data->key_idx;
324 memset(data, 0, sizeof(*data));
325 data->key_idx = keyidx;
326 data->tfm = tfm;
327 if (len == CCMP_TK_LEN) {
328 memcpy(data->key, key, CCMP_TK_LEN);
329 data->key_set = 1;
330 if (seq) {
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];
337 }
338 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
339 crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
340 return -1;
341 } else if (len == 0) {
342 data->key_set = 0;
343 } else {
344 return -1;
345 }
346
347 return 0;
348 }
349
350
rtllib_ccmp_get_key(void * key,int len,u8 * seq,void * priv)351 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
352 {
353 struct rtllib_ccmp_data *data = priv;
354
355 if (len < CCMP_TK_LEN)
356 return -1;
357
358 if (!data->key_set)
359 return 0;
360 memcpy(key, data->key, CCMP_TK_LEN);
361
362 if (seq) {
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];
369 }
370
371 return CCMP_TK_LEN;
372 }
373
374
rtllib_ccmp_print_stats(struct seq_file * m,void * priv)375 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
376 {
377 struct rtllib_ccmp_data *ccmp = priv;
378
379 seq_printf(m,
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);
386 }
387
388 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
389 .name = "R-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,
402 };
403
404
rtllib_crypto_ccmp_init(void)405 static int __init rtllib_crypto_ccmp_init(void)
406 {
407 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
408 }
409
410
rtllib_crypto_ccmp_exit(void)411 static void __exit rtllib_crypto_ccmp_exit(void)
412 {
413 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
414 }
415
416 module_init(rtllib_crypto_ccmp_init);
417 module_exit(rtllib_crypto_ccmp_exit);
418
419 MODULE_LICENSE("GPL");
420