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 == 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
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 rtllib_hdr_4addr * hdr,u8 * pn,u8 * iv,u8 * aad)86 static int ccmp_init_iv_and_aad(struct rtllib_hdr_4addr *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_ctl);
95 a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
96 (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
97
98 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
99 (WLAN_FC_GET_STYPE(fc) & 0x80));
100 aad_len = 22;
101 if (a4_included)
102 aad_len += 6;
103 if (qc_included) {
104 pos = (u8 *)&hdr->addr4;
105 if (a4_included)
106 pos += 6;
107 qc = *pos & 0x0f;
108 aad_len += 2;
109 }
110 /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
111 * mode authentication are not allowed to collide, yet both are derived
112 * from the same vector. We only set L := 1 here to indicate that the
113 * data size can be represented in (L+1) bytes. The CCM layer will take
114 * care of storing the data length in the top (L+1) bytes and setting
115 * and clearing the other bits as is required to derive the two IVs.
116 */
117 iv[0] = 0x1;
118
119 /* Nonce: QC | A2 | PN */
120 iv[1] = qc;
121 memcpy(iv + 2, hdr->addr2, ETH_ALEN);
122 memcpy(iv + 8, pn, CCMP_PN_LEN);
123
124 /* AAD:
125 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
126 * A1 | A2 | A3
127 * SC with bits 4..15 (seq#) masked to zero
128 * A4 (if present)
129 * QC (if present)
130 */
131 pos = (u8 *)hdr;
132 aad[0] = pos[0] & 0x8f;
133 aad[1] = pos[1] & 0xc7;
134 memcpy(&aad[2], &hdr->addr1, ETH_ALEN);
135 memcpy(&aad[8], &hdr->addr2, ETH_ALEN);
136 memcpy(&aad[14], &hdr->addr3, 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
rtllib_ccmp_encrypt(struct sk_buff * skb,int hdr_len,void * priv)151 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
152 {
153 struct rtllib_ccmp_data *key = priv;
154 int i;
155 u8 *pos;
156 struct rtllib_hdr_4addr *hdr;
157 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
158 MAX_DEV_ADDR_SIZE);
159 if (skb_headroom(skb) < CCMP_HDR_LEN ||
160 skb_tailroom(skb) < CCMP_MIC_LEN ||
161 skb->len < hdr_len)
162 return -1;
163
164 pos = skb_push(skb, CCMP_HDR_LEN);
165 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
166 pos += hdr_len;
167
168 i = CCMP_PN_LEN - 1;
169 while (i >= 0) {
170 key->tx_pn[i]++;
171 if (key->tx_pn[i] != 0)
172 break;
173 i--;
174 }
175
176 *pos++ = key->tx_pn[5];
177 *pos++ = key->tx_pn[4];
178 *pos++ = 0;
179 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
180 *pos++ = key->tx_pn[3];
181 *pos++ = key->tx_pn[2];
182 *pos++ = key->tx_pn[1];
183 *pos++ = key->tx_pn[0];
184
185 hdr = (struct rtllib_hdr_4addr *)skb->data;
186 if (!tcb_desc->bHwSec) {
187 struct aead_request *req;
188 struct scatterlist sg[2];
189 u8 *aad = key->tx_aad;
190 u8 iv[AES_BLOCK_LEN];
191 int aad_len, ret;
192 int data_len = skb->len - hdr_len - CCMP_HDR_LEN;
193
194 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
195 if (!req)
196 return -ENOMEM;
197
198 aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
199
200 skb_put(skb, CCMP_MIC_LEN);
201 sg_init_table(sg, 2);
202 sg_set_buf(&sg[0], aad, aad_len);
203 sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
204 data_len + CCMP_MIC_LEN);
205
206 aead_request_set_callback(req, 0, NULL, NULL);
207 aead_request_set_ad(req, aad_len);
208 aead_request_set_crypt(req, sg, sg, data_len, iv);
209
210 ret = crypto_aead_encrypt(req);
211 aead_request_free(req);
212
213 return ret;
214 }
215
216 return 0;
217 }
218
rtllib_ccmp_decrypt(struct sk_buff * skb,int hdr_len,void * priv)219 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
220 {
221 struct rtllib_ccmp_data *key = priv;
222 u8 keyidx, *pos;
223 struct rtllib_hdr_4addr *hdr;
224 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
225 MAX_DEV_ADDR_SIZE);
226 u8 pn[6];
227
228 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
229 key->dot11rsna_stats_ccmp_format_errors++;
230 return -1;
231 }
232
233 hdr = (struct rtllib_hdr_4addr *)skb->data;
234 pos = skb->data + hdr_len;
235 keyidx = pos[3];
236 if (!(keyidx & (1 << 5))) {
237 if (net_ratelimit()) {
238 pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
239 hdr->addr2);
240 }
241 key->dot11rsna_stats_ccmp_format_errors++;
242 return -2;
243 }
244 keyidx >>= 6;
245 if (key->key_idx != keyidx) {
246 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
247 key->key_idx, keyidx, priv);
248 return -6;
249 }
250 if (!key->key_set) {
251 if (net_ratelimit()) {
252 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
253 hdr->addr2, keyidx);
254 }
255 return -3;
256 }
257
258 pn[0] = pos[7];
259 pn[1] = pos[6];
260 pn[2] = pos[5];
261 pn[3] = pos[4];
262 pn[4] = pos[1];
263 pn[5] = pos[0];
264 pos += 8;
265 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
266 key->dot11rsna_stats_ccmp_replays++;
267 return -4;
268 }
269 if (!tcb_desc->bHwSec) {
270 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
271 struct aead_request *req;
272 struct scatterlist sg[2];
273 u8 *aad = key->rx_aad;
274 u8 iv[AES_BLOCK_LEN];
275 int aad_len, ret;
276
277 req = aead_request_alloc(key->tfm, GFP_ATOMIC);
278 if (!req)
279 return -ENOMEM;
280
281 aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
282
283 sg_init_table(sg, 2);
284 sg_set_buf(&sg[0], aad, aad_len);
285 sg_set_buf(&sg[1], pos, data_len);
286
287 aead_request_set_callback(req, 0, NULL, NULL);
288 aead_request_set_ad(req, aad_len);
289 aead_request_set_crypt(req, sg, sg, data_len, iv);
290
291 ret = crypto_aead_decrypt(req);
292 aead_request_free(req);
293
294 if (ret) {
295 if (net_ratelimit()) {
296 pr_debug("CCMP: decrypt failed: STA= %pM\n",
297 hdr->addr2);
298 }
299 key->dot11rsna_stats_ccmp_decrypt_errors++;
300 return -5;
301 }
302
303 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
304 }
305 /* Remove hdr and MIC */
306 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
307 skb_pull(skb, CCMP_HDR_LEN);
308 skb_trim(skb, skb->len - CCMP_MIC_LEN);
309
310 return keyidx;
311 }
312
rtllib_ccmp_set_key(void * key,int len,u8 * seq,void * priv)313 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
314 {
315 struct rtllib_ccmp_data *data = priv;
316 int keyidx;
317 struct crypto_aead *tfm = data->tfm;
318
319 keyidx = data->key_idx;
320 memset(data, 0, sizeof(*data));
321 data->key_idx = keyidx;
322 data->tfm = tfm;
323 if (len == CCMP_TK_LEN) {
324 memcpy(data->key, key, CCMP_TK_LEN);
325 data->key_set = 1;
326 if (seq) {
327 data->rx_pn[0] = seq[5];
328 data->rx_pn[1] = seq[4];
329 data->rx_pn[2] = seq[3];
330 data->rx_pn[3] = seq[2];
331 data->rx_pn[4] = seq[1];
332 data->rx_pn[5] = seq[0];
333 }
334 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
335 crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
336 return -1;
337 } else if (len == 0) {
338 data->key_set = 0;
339 } else {
340 return -1;
341 }
342
343 return 0;
344 }
345
rtllib_ccmp_get_key(void * key,int len,u8 * seq,void * priv)346 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
347 {
348 struct rtllib_ccmp_data *data = priv;
349
350 if (len < CCMP_TK_LEN)
351 return -1;
352
353 if (!data->key_set)
354 return 0;
355 memcpy(key, data->key, CCMP_TK_LEN);
356
357 if (seq) {
358 seq[0] = data->tx_pn[5];
359 seq[1] = data->tx_pn[4];
360 seq[2] = data->tx_pn[3];
361 seq[3] = data->tx_pn[2];
362 seq[4] = data->tx_pn[1];
363 seq[5] = data->tx_pn[0];
364 }
365
366 return CCMP_TK_LEN;
367 }
368
rtllib_ccmp_print_stats(struct seq_file * m,void * priv)369 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
370 {
371 struct rtllib_ccmp_data *ccmp = priv;
372
373 seq_printf(m,
374 "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n",
375 ccmp->key_idx, ccmp->key_set,
376 ccmp->tx_pn, ccmp->rx_pn,
377 ccmp->dot11rsna_stats_ccmp_format_errors,
378 ccmp->dot11rsna_stats_ccmp_replays,
379 ccmp->dot11rsna_stats_ccmp_decrypt_errors);
380 }
381
382 static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
383 .name = "R-CCMP",
384 .init = rtllib_ccmp_init,
385 .deinit = rtllib_ccmp_deinit,
386 .encrypt_mpdu = rtllib_ccmp_encrypt,
387 .decrypt_mpdu = rtllib_ccmp_decrypt,
388 .encrypt_msdu = NULL,
389 .decrypt_msdu = NULL,
390 .set_key = rtllib_ccmp_set_key,
391 .get_key = rtllib_ccmp_get_key,
392 .print_stats = rtllib_ccmp_print_stats,
393 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
394 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
395 .owner = THIS_MODULE,
396 };
397
rtllib_crypto_ccmp_init(void)398 static int __init rtllib_crypto_ccmp_init(void)
399 {
400 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
401 }
402
rtllib_crypto_ccmp_exit(void)403 static void __exit rtllib_crypto_ccmp_exit(void)
404 {
405 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
406 }
407
408 module_init(rtllib_crypto_ccmp_init);
409 module_exit(rtllib_crypto_ccmp_exit);
410
411 MODULE_LICENSE("GPL");
412