2 * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
4 * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation. See README and COPYING for
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/random.h>
17 #include <linux/skbuff.h>
18 #include <linux/netdevice.h>
19 #include <linux/if_ether.h>
20 #include <linux/if_arp.h>
21 #include <linux/string.h>
22 #include <linux/wireless.h>
24 #include "ieee80211.h"
26 #include <linux/crypto.h>
27 #include <linux/scatterlist.h>
29 MODULE_AUTHOR("Jouni Malinen");
30 MODULE_DESCRIPTION("Host AP crypt: CCMP");
31 MODULE_LICENSE("GPL");
34 #define AES_BLOCK_LEN 16
35 #define CCMP_HDR_LEN 8
36 #define CCMP_MIC_LEN 8
37 #define CCMP_TK_LEN 16
40 struct ieee80211_ccmp_data {
44 u8 tx_pn[CCMP_PN_LEN];
45 u8 rx_pn[CCMP_PN_LEN];
47 u32 dot11RSNAStatsCCMPFormatErrors;
48 u32 dot11RSNAStatsCCMPReplays;
49 u32 dot11RSNAStatsCCMPDecryptErrors;
53 struct crypto_tfm *tfm;
55 /* scratch buffers for virt_to_page() (crypto API) */
56 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
57 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
58 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
61 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
62 const u8 pt[16], u8 ct[16])
64 crypto_cipher_encrypt_one((void *)tfm, ct, pt);
67 static void *ieee80211_ccmp_init(int key_idx)
69 struct ieee80211_ccmp_data *priv;
71 priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
74 priv->key_idx = key_idx;
76 priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
77 if (IS_ERR(priv->tfm)) {
78 pr_debug("could not allocate crypto API aes\n");
88 crypto_free_cipher((void *)priv->tfm);
96 static void ieee80211_ccmp_deinit(void *priv)
98 struct ieee80211_ccmp_data *_priv = priv;
100 if (_priv && _priv->tfm)
101 crypto_free_cipher((void *)_priv->tfm);
106 static inline void xor_block(u8 *b, u8 *a, size_t len)
109 for (i = 0; i < len; i++)
113 static void ccmp_init_blocks(struct crypto_tfm *tfm,
114 struct ieee80211_hdr_4addr *hdr,
115 u8 *pn, size_t dlen, u8 *b0, u8 *auth,
121 int a4_included, qc_included;
122 u8 aad[2 * AES_BLOCK_LEN];
124 fc = le16_to_cpu(hdr->frame_ctl);
125 a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
126 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
128 qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
129 (WLAN_FC_GET_STYPE(fc) & 0x08));
131 qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
132 (WLAN_FC_GET_STYPE(fc) & 0x80));
137 pos = (u8 *) &hdr->addr4;
143 /* CCM Initial Block:
144 * Flag (Include authentication header, M=3 (8-octet MIC),
145 * L=1 (2-octet Dlen))
146 * Nonce: 0x00 | A2 | PN
150 memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
151 memcpy(b0 + 8, pn, CCMP_PN_LEN);
152 b0[14] = (dlen >> 8) & 0xff;
153 b0[15] = dlen & 0xff;
156 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
158 * SC with bits 4..15 (seq#) masked to zero
163 aad[0] = 0; /* aad_len >> 8 */
164 aad[1] = aad_len & 0xff;
165 aad[2] = pos[0] & 0x8f;
166 aad[3] = pos[1] & 0xc7;
167 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
168 pos = (u8 *) &hdr->seq_ctl;
169 aad[22] = pos[0] & 0x0f;
170 aad[23] = 0; /* all bits masked */
171 memset(aad + 24, 0, 8);
173 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
175 aad[a4_included ? 30 : 24] = qc;
176 /* rest of QC masked */
179 /* Start with the first block and AAD */
180 ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
181 xor_block(auth, aad, AES_BLOCK_LEN);
182 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
183 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
184 ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
187 ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
190 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
192 struct ieee80211_ccmp_data *key = priv;
195 struct ieee80211_hdr_4addr *hdr;
196 int blocks, last, len;
203 if (skb_headroom(skb) < CCMP_HDR_LEN ||
204 skb_tailroom(skb) < CCMP_MIC_LEN ||
208 data_len = skb->len - hdr_len;
209 pos = skb_push(skb, CCMP_HDR_LEN);
210 memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
216 if (key->tx_pn[i] != 0)
221 *pos++ = key->tx_pn[5];
222 *pos++ = key->tx_pn[4];
224 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
225 *pos++ = key->tx_pn[3];
226 *pos++ = key->tx_pn[2];
227 *pos++ = key->tx_pn[1];
228 *pos++ = key->tx_pn[0];
230 hdr = (struct ieee80211_hdr_4addr *)skb->data;
231 mic = skb_put(skb, CCMP_MIC_LEN);
233 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
235 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
236 last = data_len % AES_BLOCK_LEN;
238 for (i = 1; i <= blocks; i++) {
239 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
241 xor_block(b, pos, len);
242 ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
243 /* Encryption, with counter */
244 b0[14] = (i >> 8) & 0xff;
246 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
247 xor_block(pos, e, len);
251 for (i = 0; i < CCMP_MIC_LEN; i++)
252 mic[i] = b[i] ^ s0[i];
258 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
260 struct ieee80211_ccmp_data *key = priv;
262 struct ieee80211_hdr_4addr *hdr;
264 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
265 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
269 int i, blocks, last, len;
271 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
272 key->dot11RSNAStatsCCMPFormatErrors++;
276 hdr = (struct ieee80211_hdr_4addr *)skb->data;
277 pos = skb->data + hdr_len;
279 if (!(keyidx & (1 << 5))) {
280 if (net_ratelimit()) {
281 pr_debug("received packet without ExtIV flag from %pM\n",
284 key->dot11RSNAStatsCCMPFormatErrors++;
288 if (key->key_idx != keyidx) {
289 pr_debug("RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
290 key->key_idx, keyidx, priv);
294 if (net_ratelimit()) {
295 pr_debug("received packet from %pM with keyid=%d that does not have a configured key\n",
309 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
310 if (net_ratelimit()) {
311 pr_debug("replay detected: STA=%pM previous PN %pm received PN %pm\n",
312 hdr->addr2, key->rx_pn, pn);
314 key->dot11RSNAStatsCCMPReplays++;
318 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
319 xor_block(mic, b, CCMP_MIC_LEN);
321 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
322 last = data_len % AES_BLOCK_LEN;
324 for (i = 1; i <= blocks; i++) {
325 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
326 /* Decrypt, with counter */
327 b0[14] = (i >> 8) & 0xff;
329 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
330 xor_block(pos, b, len);
332 xor_block(a, pos, len);
333 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
337 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
339 pr_debug("decrypt failed: STA=%pM\n", hdr->addr2);
341 key->dot11RSNAStatsCCMPDecryptErrors++;
345 memcpy(key->rx_pn, pn, CCMP_PN_LEN);
347 /* Remove hdr and MIC */
348 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
349 skb_pull(skb, CCMP_HDR_LEN);
350 skb_trim(skb, skb->len - CCMP_MIC_LEN);
356 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
358 struct ieee80211_ccmp_data *data = priv;
360 struct crypto_tfm *tfm = data->tfm;
362 keyidx = data->key_idx;
363 memset(data, 0, sizeof(*data));
364 data->key_idx = keyidx;
366 if (len == CCMP_TK_LEN) {
367 memcpy(data->key, key, CCMP_TK_LEN);
370 data->rx_pn[0] = seq[5];
371 data->rx_pn[1] = seq[4];
372 data->rx_pn[2] = seq[3];
373 data->rx_pn[3] = seq[2];
374 data->rx_pn[4] = seq[1];
375 data->rx_pn[5] = seq[0];
377 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
387 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
389 struct ieee80211_ccmp_data *data = priv;
391 if (len < CCMP_TK_LEN)
396 memcpy(key, data->key, CCMP_TK_LEN);
399 seq[0] = data->tx_pn[5];
400 seq[1] = data->tx_pn[4];
401 seq[2] = data->tx_pn[3];
402 seq[3] = data->tx_pn[2];
403 seq[4] = data->tx_pn[1];
404 seq[5] = data->tx_pn[0];
411 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
413 struct ieee80211_ccmp_data *ccmp = priv;
415 "key[%d] alg=CCMP key_set=%d tx_pn=%pm rx_pn=%pm format_errors=%d replays=%d decrypt_errors=%d\n",
416 ccmp->key_idx, ccmp->key_set,
417 ccmp->tx_pn, ccmp->rx_pn,
418 ccmp->dot11RSNAStatsCCMPFormatErrors,
419 ccmp->dot11RSNAStatsCCMPReplays,
420 ccmp->dot11RSNAStatsCCMPDecryptErrors);
425 void ieee80211_ccmp_null(void)
429 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
431 .init = ieee80211_ccmp_init,
432 .deinit = ieee80211_ccmp_deinit,
433 .encrypt_mpdu = ieee80211_ccmp_encrypt,
434 .decrypt_mpdu = ieee80211_ccmp_decrypt,
435 .encrypt_msdu = NULL,
436 .decrypt_msdu = NULL,
437 .set_key = ieee80211_ccmp_set_key,
438 .get_key = ieee80211_ccmp_get_key,
439 .print_stats = ieee80211_ccmp_print_stats,
440 .extra_prefix_len = CCMP_HDR_LEN,
441 .extra_postfix_len = CCMP_MIC_LEN,
442 .owner = THIS_MODULE,
446 int ieee80211_crypto_ccmp_init(void)
448 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
452 void ieee80211_crypto_ccmp_exit(void)
454 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);