Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6] / net / ieee80211 / ieee80211_crypt_ccmp.c
1 /*
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  * 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
9  * more details.
10  */
11
12 #include <linux/config.h>
13 #include <linux/version.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/random.h>
18 #include <linux/skbuff.h>
19 #include <linux/netdevice.h>
20 #include <linux/if_ether.h>
21 #include <linux/if_arp.h>
22 #include <asm/string.h>
23 #include <linux/wireless.h>
24
25 #include <net/ieee80211.h>
26
27 #include <linux/crypto.h>
28 #include <asm/scatterlist.h>
29
30 MODULE_AUTHOR("Jouni Malinen");
31 MODULE_DESCRIPTION("Host AP crypt: CCMP");
32 MODULE_LICENSE("GPL");
33
34 #define AES_BLOCK_LEN 16
35 #define CCMP_HDR_LEN 8
36 #define CCMP_MIC_LEN 8
37 #define CCMP_TK_LEN 16
38 #define CCMP_PN_LEN 6
39
40 struct ieee80211_ccmp_data {
41         u8 key[CCMP_TK_LEN];
42         int key_set;
43
44         u8 tx_pn[CCMP_PN_LEN];
45         u8 rx_pn[CCMP_PN_LEN];
46
47         u32 dot11RSNAStatsCCMPFormatErrors;
48         u32 dot11RSNAStatsCCMPReplays;
49         u32 dot11RSNAStatsCCMPDecryptErrors;
50
51         int key_idx;
52
53         struct crypto_tfm *tfm;
54
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];
59 };
60
61 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
62                                        const u8 pt[16], u8 ct[16])
63 {
64         struct scatterlist src, dst;
65
66         src.page = virt_to_page(pt);
67         src.offset = offset_in_page(pt);
68         src.length = AES_BLOCK_LEN;
69
70         dst.page = virt_to_page(ct);
71         dst.offset = offset_in_page(ct);
72         dst.length = AES_BLOCK_LEN;
73
74         crypto_cipher_encrypt(tfm, &dst, &src, AES_BLOCK_LEN);
75 }
76
77 static void *ieee80211_ccmp_init(int key_idx)
78 {
79         struct ieee80211_ccmp_data *priv;
80
81         priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
82         if (priv == NULL)
83                 goto fail;
84         memset(priv, 0, sizeof(*priv));
85         priv->key_idx = key_idx;
86
87         priv->tfm = crypto_alloc_tfm("aes", 0);
88         if (priv->tfm == NULL) {
89                 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate "
90                        "crypto API aes\n");
91                 goto fail;
92         }
93
94         return priv;
95
96       fail:
97         if (priv) {
98                 if (priv->tfm)
99                         crypto_free_tfm(priv->tfm);
100                 kfree(priv);
101         }
102
103         return NULL;
104 }
105
106 static void ieee80211_ccmp_deinit(void *priv)
107 {
108         struct ieee80211_ccmp_data *_priv = priv;
109         if (_priv && _priv->tfm)
110                 crypto_free_tfm(_priv->tfm);
111         kfree(priv);
112 }
113
114 static inline void xor_block(u8 * b, u8 * a, size_t len)
115 {
116         int i;
117         for (i = 0; i < len; i++)
118                 b[i] ^= a[i];
119 }
120
121 static void ccmp_init_blocks(struct crypto_tfm *tfm,
122                              struct ieee80211_hdr *hdr,
123                              u8 * pn, size_t dlen, u8 * b0, u8 * auth, u8 * s0)
124 {
125         u8 *pos, qc = 0;
126         size_t aad_len;
127         u16 fc;
128         int a4_included, qc_included;
129         u8 aad[2 * AES_BLOCK_LEN];
130
131         fc = le16_to_cpu(hdr->frame_ctl);
132         a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
133                        (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
134         qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
135                        (WLAN_FC_GET_STYPE(fc) & 0x08));
136         aad_len = 22;
137         if (a4_included)
138                 aad_len += 6;
139         if (qc_included) {
140                 pos = (u8 *) & hdr->addr4;
141                 if (a4_included)
142                         pos += 6;
143                 qc = *pos & 0x0f;
144                 aad_len += 2;
145         }
146
147         /* CCM Initial Block:
148          * Flag (Include authentication header, M=3 (8-octet MIC),
149          *       L=1 (2-octet Dlen))
150          * Nonce: 0x00 | A2 | PN
151          * Dlen */
152         b0[0] = 0x59;
153         b0[1] = qc;
154         memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
155         memcpy(b0 + 8, pn, CCMP_PN_LEN);
156         b0[14] = (dlen >> 8) & 0xff;
157         b0[15] = dlen & 0xff;
158
159         /* AAD:
160          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
161          * A1 | A2 | A3
162          * SC with bits 4..15 (seq#) masked to zero
163          * A4 (if present)
164          * QC (if present)
165          */
166         pos = (u8 *) hdr;
167         aad[0] = 0;             /* aad_len >> 8 */
168         aad[1] = aad_len & 0xff;
169         aad[2] = pos[0] & 0x8f;
170         aad[3] = pos[1] & 0xc7;
171         memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
172         pos = (u8 *) & hdr->seq_ctl;
173         aad[22] = pos[0] & 0x0f;
174         aad[23] = 0;            /* all bits masked */
175         memset(aad + 24, 0, 8);
176         if (a4_included)
177                 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
178         if (qc_included) {
179                 aad[a4_included ? 30 : 24] = qc;
180                 /* rest of QC masked */
181         }
182
183         /* Start with the first block and AAD */
184         ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
185         xor_block(auth, aad, AES_BLOCK_LEN);
186         ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
187         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
188         ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
189         b0[0] &= 0x07;
190         b0[14] = b0[15] = 0;
191         ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
192 }
193
194 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
195 {
196         struct ieee80211_ccmp_data *key = priv;
197         int data_len, i, blocks, last, len;
198         u8 *pos, *mic;
199         struct ieee80211_hdr *hdr;
200         u8 *b0 = key->tx_b0;
201         u8 *b = key->tx_b;
202         u8 *e = key->tx_e;
203         u8 *s0 = key->tx_s0;
204
205         if (skb_headroom(skb) < CCMP_HDR_LEN ||
206             skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
207                 return -1;
208
209         data_len = skb->len - hdr_len;
210         pos = skb_push(skb, CCMP_HDR_LEN);
211         memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
212         pos += hdr_len;
213         mic = skb_put(skb, CCMP_MIC_LEN);
214
215         i = CCMP_PN_LEN - 1;
216         while (i >= 0) {
217                 key->tx_pn[i]++;
218                 if (key->tx_pn[i] != 0)
219                         break;
220                 i--;
221         }
222
223         *pos++ = key->tx_pn[5];
224         *pos++ = key->tx_pn[4];
225         *pos++ = 0;
226         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
227         *pos++ = key->tx_pn[3];
228         *pos++ = key->tx_pn[2];
229         *pos++ = key->tx_pn[1];
230         *pos++ = key->tx_pn[0];
231
232         hdr = (struct ieee80211_hdr *)skb->data;
233         ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
234
235         blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
236         last = data_len % AES_BLOCK_LEN;
237
238         for (i = 1; i <= blocks; i++) {
239                 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
240                 /* Authentication */
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;
245                 b0[15] = i & 0xff;
246                 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
247                 xor_block(pos, e, len);
248                 pos += len;
249         }
250
251         for (i = 0; i < CCMP_MIC_LEN; i++)
252                 mic[i] = b[i] ^ s0[i];
253
254         return 0;
255 }
256
257 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
258 {
259         struct ieee80211_ccmp_data *key = priv;
260         u8 keyidx, *pos;
261         struct ieee80211_hdr *hdr;
262         u8 *b0 = key->rx_b0;
263         u8 *b = key->rx_b;
264         u8 *a = key->rx_a;
265         u8 pn[6];
266         int i, blocks, last, len;
267         size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
268         u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
269
270         if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
271                 key->dot11RSNAStatsCCMPFormatErrors++;
272                 return -1;
273         }
274
275         hdr = (struct ieee80211_hdr *)skb->data;
276         pos = skb->data + hdr_len;
277         keyidx = pos[3];
278         if (!(keyidx & (1 << 5))) {
279                 if (net_ratelimit()) {
280                         printk(KERN_DEBUG "CCMP: received packet without ExtIV"
281                                " flag from " MAC_FMT "\n", MAC_ARG(hdr->addr2));
282                 }
283                 key->dot11RSNAStatsCCMPFormatErrors++;
284                 return -2;
285         }
286         keyidx >>= 6;
287         if (key->key_idx != keyidx) {
288                 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
289                        "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
290                 return -6;
291         }
292         if (!key->key_set) {
293                 if (net_ratelimit()) {
294                         printk(KERN_DEBUG "CCMP: received packet from " MAC_FMT
295                                " with keyid=%d that does not have a configured"
296                                " key\n", MAC_ARG(hdr->addr2), keyidx);
297                 }
298                 return -3;
299         }
300
301         pn[0] = pos[7];
302         pn[1] = pos[6];
303         pn[2] = pos[5];
304         pn[3] = pos[4];
305         pn[4] = pos[1];
306         pn[5] = pos[0];
307         pos += 8;
308
309         if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
310                 if (net_ratelimit()) {
311                         printk(KERN_DEBUG "CCMP: replay detected: STA=" MAC_FMT
312                                " previous PN %02x%02x%02x%02x%02x%02x "
313                                "received PN %02x%02x%02x%02x%02x%02x\n",
314                                MAC_ARG(hdr->addr2), MAC_ARG(key->rx_pn),
315                                MAC_ARG(pn));
316                 }
317                 key->dot11RSNAStatsCCMPReplays++;
318                 return -4;
319         }
320
321         ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
322         xor_block(mic, b, CCMP_MIC_LEN);
323
324         blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
325         last = data_len % AES_BLOCK_LEN;
326
327         for (i = 1; i <= blocks; i++) {
328                 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
329                 /* Decrypt, with counter */
330                 b0[14] = (i >> 8) & 0xff;
331                 b0[15] = i & 0xff;
332                 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
333                 xor_block(pos, b, len);
334                 /* Authentication */
335                 xor_block(a, pos, len);
336                 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
337                 pos += len;
338         }
339
340         if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
341                 if (net_ratelimit()) {
342                         printk(KERN_DEBUG "CCMP: decrypt failed: STA="
343                                MAC_FMT "\n", MAC_ARG(hdr->addr2));
344                 }
345                 key->dot11RSNAStatsCCMPDecryptErrors++;
346                 return -5;
347         }
348
349         memcpy(key->rx_pn, pn, CCMP_PN_LEN);
350
351         /* Remove hdr and MIC */
352         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
353         skb_pull(skb, CCMP_HDR_LEN);
354         skb_trim(skb, skb->len - CCMP_MIC_LEN);
355
356         return keyidx;
357 }
358
359 static int ieee80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
360 {
361         struct ieee80211_ccmp_data *data = priv;
362         int keyidx;
363         struct crypto_tfm *tfm = data->tfm;
364
365         keyidx = data->key_idx;
366         memset(data, 0, sizeof(*data));
367         data->key_idx = keyidx;
368         data->tfm = tfm;
369         if (len == CCMP_TK_LEN) {
370                 memcpy(data->key, key, CCMP_TK_LEN);
371                 data->key_set = 1;
372                 if (seq) {
373                         data->rx_pn[0] = seq[5];
374                         data->rx_pn[1] = seq[4];
375                         data->rx_pn[2] = seq[3];
376                         data->rx_pn[3] = seq[2];
377                         data->rx_pn[4] = seq[1];
378                         data->rx_pn[5] = seq[0];
379                 }
380                 crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN);
381         } else if (len == 0)
382                 data->key_set = 0;
383         else
384                 return -1;
385
386         return 0;
387 }
388
389 static int ieee80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
390 {
391         struct ieee80211_ccmp_data *data = priv;
392
393         if (len < CCMP_TK_LEN)
394                 return -1;
395
396         if (!data->key_set)
397                 return 0;
398         memcpy(key, data->key, CCMP_TK_LEN);
399
400         if (seq) {
401                 seq[0] = data->tx_pn[5];
402                 seq[1] = data->tx_pn[4];
403                 seq[2] = data->tx_pn[3];
404                 seq[3] = data->tx_pn[2];
405                 seq[4] = data->tx_pn[1];
406                 seq[5] = data->tx_pn[0];
407         }
408
409         return CCMP_TK_LEN;
410 }
411
412 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
413 {
414         struct ieee80211_ccmp_data *ccmp = priv;
415         p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
416                      "tx_pn=%02x%02x%02x%02x%02x%02x "
417                      "rx_pn=%02x%02x%02x%02x%02x%02x "
418                      "format_errors=%d replays=%d decrypt_errors=%d\n",
419                      ccmp->key_idx, ccmp->key_set,
420                      MAC_ARG(ccmp->tx_pn), MAC_ARG(ccmp->rx_pn),
421                      ccmp->dot11RSNAStatsCCMPFormatErrors,
422                      ccmp->dot11RSNAStatsCCMPReplays,
423                      ccmp->dot11RSNAStatsCCMPDecryptErrors);
424
425         return p;
426 }
427
428 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
429         .name                   = "CCMP",
430         .init                   = ieee80211_ccmp_init,
431         .deinit                 = ieee80211_ccmp_deinit,
432         .encrypt_mpdu           = ieee80211_ccmp_encrypt,
433         .decrypt_mpdu           = ieee80211_ccmp_decrypt,
434         .encrypt_msdu           = NULL,
435         .decrypt_msdu           = NULL,
436         .set_key                = ieee80211_ccmp_set_key,
437         .get_key                = ieee80211_ccmp_get_key,
438         .print_stats            = ieee80211_ccmp_print_stats,
439         .extra_prefix_len       = CCMP_HDR_LEN,
440         .extra_postfix_len      = CCMP_MIC_LEN,
441         .owner                  = THIS_MODULE,
442 };
443
444 static int __init ieee80211_crypto_ccmp_init(void)
445 {
446         return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
447 }
448
449 static void __exit ieee80211_crypto_ccmp_exit(void)
450 {
451         ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
452 }
453
454 module_init(ieee80211_crypto_ccmp_init);
455 module_exit(ieee80211_crypto_ccmp_exit);