1 // SPDX-License-Identifier: GPL-2.0-only
3 * lib80211 crypt: host-based CCMP encryption implementation for lib80211
5 * Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi>
6 * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
9 #include <linux/kernel.h>
10 #include <linux/err.h>
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/slab.h>
14 #include <linux/random.h>
15 #include <linux/skbuff.h>
16 #include <linux/netdevice.h>
17 #include <linux/if_ether.h>
18 #include <linux/if_arp.h>
19 #include <asm/string.h>
20 #include <linux/wireless.h>
22 #include <linux/ieee80211.h>
24 #include <linux/crypto.h>
26 #include <net/lib80211.h>
28 MODULE_AUTHOR("Jouni Malinen");
29 MODULE_DESCRIPTION("Host AP crypt: CCMP");
30 MODULE_LICENSE("GPL");
32 #define AES_BLOCK_LEN 16
33 #define CCMP_HDR_LEN 8
34 #define CCMP_MIC_LEN 8
35 #define CCMP_TK_LEN 16
38 struct lib80211_ccmp_data {
42 u8 tx_pn[CCMP_PN_LEN];
43 u8 rx_pn[CCMP_PN_LEN];
45 u32 dot11RSNAStatsCCMPFormatErrors;
46 u32 dot11RSNAStatsCCMPReplays;
47 u32 dot11RSNAStatsCCMPDecryptErrors;
51 struct crypto_cipher *tfm;
53 /* scratch buffers for virt_to_page() (crypto API) */
54 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
55 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
56 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
59 static inline void lib80211_ccmp_aes_encrypt(struct crypto_cipher *tfm,
60 const u8 pt[16], u8 ct[16])
62 crypto_cipher_encrypt_one(tfm, ct, pt);
65 static void *lib80211_ccmp_init(int key_idx)
67 struct lib80211_ccmp_data *priv;
69 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
72 priv->key_idx = key_idx;
74 priv->tfm = crypto_alloc_cipher("aes", 0, 0);
75 if (IS_ERR(priv->tfm)) {
85 crypto_free_cipher(priv->tfm);
92 static void lib80211_ccmp_deinit(void *priv)
94 struct lib80211_ccmp_data *_priv = priv;
95 if (_priv && _priv->tfm)
96 crypto_free_cipher(_priv->tfm);
100 static inline void xor_block(u8 * b, u8 * a, size_t len)
103 for (i = 0; i < len; i++)
107 static void ccmp_init_blocks(struct crypto_cipher *tfm,
108 struct ieee80211_hdr *hdr,
109 u8 * pn, size_t dlen, u8 * b0, u8 * auth, u8 * s0)
113 int a4_included, qc_included;
114 u8 aad[2 * AES_BLOCK_LEN];
116 a4_included = ieee80211_has_a4(hdr->frame_control);
117 qc_included = ieee80211_is_data_qos(hdr->frame_control);
123 pos = (u8 *) & hdr->addr4;
130 /* CCM Initial Block:
131 * Flag (Include authentication header, M=3 (8-octet MIC),
132 * L=1 (2-octet Dlen))
133 * Nonce: 0x00 | A2 | PN
137 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
138 memcpy(b0 + 8, pn, CCMP_PN_LEN);
139 b0[14] = (dlen >> 8) & 0xff;
140 b0[15] = dlen & 0xff;
143 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
145 * SC with bits 4..15 (seq#) masked to zero
150 aad[0] = 0; /* aad_len >> 8 */
151 aad[1] = aad_len & 0xff;
152 aad[2] = pos[0] & 0x8f;
153 aad[3] = pos[1] & 0xc7;
154 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
155 pos = (u8 *) & hdr->seq_ctrl;
156 aad[22] = pos[0] & 0x0f;
157 aad[23] = 0; /* all bits masked */
158 memset(aad + 24, 0, 8);
160 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
162 aad[a4_included ? 30 : 24] = qc;
163 /* rest of QC masked */
166 /* Start with the first block and AAD */
167 lib80211_ccmp_aes_encrypt(tfm, b0, auth);
168 xor_block(auth, aad, AES_BLOCK_LEN);
169 lib80211_ccmp_aes_encrypt(tfm, auth, auth);
170 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
171 lib80211_ccmp_aes_encrypt(tfm, auth, auth);
174 lib80211_ccmp_aes_encrypt(tfm, b0, s0);
177 static int lib80211_ccmp_hdr(struct sk_buff *skb, int hdr_len,
178 u8 *aeskey, int keylen, void *priv)
180 struct lib80211_ccmp_data *key = priv;
184 if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
187 if (aeskey != NULL && keylen >= CCMP_TK_LEN)
188 memcpy(aeskey, key->key, CCMP_TK_LEN);
190 pos = skb_push(skb, CCMP_HDR_LEN);
191 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
197 if (key->tx_pn[i] != 0)
202 *pos++ = key->tx_pn[5];
203 *pos++ = key->tx_pn[4];
205 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
206 *pos++ = key->tx_pn[3];
207 *pos++ = key->tx_pn[2];
208 *pos++ = key->tx_pn[1];
209 *pos++ = key->tx_pn[0];
214 static int lib80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
216 struct lib80211_ccmp_data *key = priv;
217 int data_len, i, blocks, last, len;
219 struct ieee80211_hdr *hdr;
225 if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
228 data_len = skb->len - hdr_len;
229 len = lib80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
233 pos = skb->data + hdr_len + CCMP_HDR_LEN;
234 hdr = (struct ieee80211_hdr *)skb->data;
235 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
237 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
238 last = data_len % AES_BLOCK_LEN;
240 for (i = 1; i <= blocks; i++) {
241 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
243 xor_block(b, pos, len);
244 lib80211_ccmp_aes_encrypt(key->tfm, b, b);
245 /* Encryption, with counter */
246 b0[14] = (i >> 8) & 0xff;
248 lib80211_ccmp_aes_encrypt(key->tfm, b0, e);
249 xor_block(pos, e, len);
253 mic = skb_put(skb, CCMP_MIC_LEN);
254 for (i = 0; i < CCMP_MIC_LEN; i++)
255 mic[i] = b[i] ^ s0[i];
261 * deal with seq counter wrapping correctly.
262 * refer to timer_after() for jiffies wrapping handling
264 static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
269 iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
270 iv16_n = (pn_n[4] << 8) | pn_n[5];
272 iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
273 iv16_o = (pn_o[4] << 8) | pn_o[5];
275 if ((s32)iv32_n - (s32)iv32_o < 0 ||
276 (iv32_n == iv32_o && iv16_n <= iv16_o))
281 static int lib80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
283 struct lib80211_ccmp_data *key = priv;
285 struct ieee80211_hdr *hdr;
290 int i, blocks, last, len;
291 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
292 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
294 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
295 key->dot11RSNAStatsCCMPFormatErrors++;
299 hdr = (struct ieee80211_hdr *)skb->data;
300 pos = skb->data + hdr_len;
302 if (!(keyidx & (1 << 5))) {
303 net_dbg_ratelimited("CCMP: received packet without ExtIV flag from %pM\n",
305 key->dot11RSNAStatsCCMPFormatErrors++;
309 if (key->key_idx != keyidx) {
310 net_dbg_ratelimited("CCMP: RX tkey->key_idx=%d frame keyidx=%d\n",
311 key->key_idx, keyidx);
315 net_dbg_ratelimited("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
328 if (ccmp_replay_check(pn, key->rx_pn)) {
329 #ifdef CONFIG_LIB80211_DEBUG
330 net_dbg_ratelimited("CCMP: replay detected: STA=%pM previous PN %02x%02x%02x%02x%02x%02x received PN %02x%02x%02x%02x%02x%02x\n",
332 key->rx_pn[0], key->rx_pn[1], key->rx_pn[2],
333 key->rx_pn[3], key->rx_pn[4], key->rx_pn[5],
334 pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]);
336 key->dot11RSNAStatsCCMPReplays++;
340 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
341 xor_block(mic, b, CCMP_MIC_LEN);
343 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
344 last = data_len % AES_BLOCK_LEN;
346 for (i = 1; i <= blocks; i++) {
347 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
348 /* Decrypt, with counter */
349 b0[14] = (i >> 8) & 0xff;
351 lib80211_ccmp_aes_encrypt(key->tfm, b0, b);
352 xor_block(pos, b, len);
354 xor_block(a, pos, len);
355 lib80211_ccmp_aes_encrypt(key->tfm, a, a);
359 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
360 net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM\n",
362 key->dot11RSNAStatsCCMPDecryptErrors++;
366 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
368 /* Remove hdr and MIC */
369 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
370 skb_pull(skb, CCMP_HDR_LEN);
371 skb_trim(skb, skb->len - CCMP_MIC_LEN);
376 static int lib80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
378 struct lib80211_ccmp_data *data = priv;
380 struct crypto_cipher *tfm = data->tfm;
382 keyidx = data->key_idx;
383 memset(data, 0, sizeof(*data));
384 data->key_idx = keyidx;
386 if (len == CCMP_TK_LEN) {
387 memcpy(data->key, key, CCMP_TK_LEN);
390 data->rx_pn[0] = seq[5];
391 data->rx_pn[1] = seq[4];
392 data->rx_pn[2] = seq[3];
393 data->rx_pn[3] = seq[2];
394 data->rx_pn[4] = seq[1];
395 data->rx_pn[5] = seq[0];
397 crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN);
406 static int lib80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
408 struct lib80211_ccmp_data *data = priv;
410 if (len < CCMP_TK_LEN)
415 memcpy(key, data->key, CCMP_TK_LEN);
418 seq[0] = data->tx_pn[5];
419 seq[1] = data->tx_pn[4];
420 seq[2] = data->tx_pn[3];
421 seq[3] = data->tx_pn[2];
422 seq[4] = data->tx_pn[1];
423 seq[5] = data->tx_pn[0];
429 static void lib80211_ccmp_print_stats(struct seq_file *m, void *priv)
431 struct lib80211_ccmp_data *ccmp = priv;
434 "key[%d] alg=CCMP key_set=%d "
435 "tx_pn=%02x%02x%02x%02x%02x%02x "
436 "rx_pn=%02x%02x%02x%02x%02x%02x "
437 "format_errors=%d replays=%d decrypt_errors=%d\n",
438 ccmp->key_idx, ccmp->key_set,
439 ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2],
440 ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5],
441 ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2],
442 ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5],
443 ccmp->dot11RSNAStatsCCMPFormatErrors,
444 ccmp->dot11RSNAStatsCCMPReplays,
445 ccmp->dot11RSNAStatsCCMPDecryptErrors);
448 static struct lib80211_crypto_ops lib80211_crypt_ccmp = {
450 .init = lib80211_ccmp_init,
451 .deinit = lib80211_ccmp_deinit,
452 .encrypt_mpdu = lib80211_ccmp_encrypt,
453 .decrypt_mpdu = lib80211_ccmp_decrypt,
454 .encrypt_msdu = NULL,
455 .decrypt_msdu = NULL,
456 .set_key = lib80211_ccmp_set_key,
457 .get_key = lib80211_ccmp_get_key,
458 .print_stats = lib80211_ccmp_print_stats,
459 .extra_mpdu_prefix_len = CCMP_HDR_LEN,
460 .extra_mpdu_postfix_len = CCMP_MIC_LEN,
461 .owner = THIS_MODULE,
464 static int __init lib80211_crypto_ccmp_init(void)
466 return lib80211_register_crypto_ops(&lib80211_crypt_ccmp);
469 static void __exit lib80211_crypto_ccmp_exit(void)
471 lib80211_unregister_crypto_ops(&lib80211_crypt_ccmp);
474 module_init(lib80211_crypto_ccmp_init);
475 module_exit(lib80211_crypto_ccmp_exit);