Root/drivers/staging/rtl8192e/rtllib_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/module.h>
13#include <linux/init.h>
14#include <linux/slab.h>
15#include <linux/random.h>
16#include <linux/skbuff.h>
17#include <linux/netdevice.h>
18#include <linux/if_ether.h>
19#include <linux/if_arp.h>
20#include <linux/string.h>
21#include <linux/wireless.h>
22#include "rtllib.h"
23
24#include <linux/crypto.h>
25
26#include <linux/scatterlist.h>
27
28#define AES_BLOCK_LEN 16
29#define CCMP_HDR_LEN 8
30#define CCMP_MIC_LEN 8
31#define CCMP_TK_LEN 16
32#define CCMP_PN_LEN 6
33
34struct rtllib_ccmp_data {
35    u8 key[CCMP_TK_LEN];
36    int key_set;
37
38    u8 tx_pn[CCMP_PN_LEN];
39    u8 rx_pn[CCMP_PN_LEN];
40
41    u32 dot11RSNAStatsCCMPFormatErrors;
42    u32 dot11RSNAStatsCCMPReplays;
43    u32 dot11RSNAStatsCCMPDecryptErrors;
44
45    int key_idx;
46
47    struct crypto_tfm *tfm;
48
49    /* scratch buffers for virt_to_page() (crypto API) */
50    u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
51        tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
52    u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
53};
54
55static void rtllib_ccmp_aes_encrypt(struct crypto_tfm *tfm,
56                 const u8 pt[16], u8 ct[16])
57{
58    crypto_cipher_encrypt_one((void *)tfm, ct, pt);
59}
60
61static void *rtllib_ccmp_init(int key_idx)
62{
63    struct rtllib_ccmp_data *priv;
64
65    priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
66    if (priv == NULL)
67        goto fail;
68    priv->key_idx = key_idx;
69
70    priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
71    if (IS_ERR(priv->tfm)) {
72        printk(KERN_DEBUG "rtllib_crypt_ccmp: could not allocate "
73               "crypto API aes\n");
74        priv->tfm = NULL;
75        goto fail;
76    }
77    return priv;
78
79fail:
80    if (priv) {
81        if (priv->tfm)
82            crypto_free_cipher((void *)priv->tfm);
83        kfree(priv);
84    }
85
86    return NULL;
87}
88
89
90static void rtllib_ccmp_deinit(void *priv)
91{
92    struct rtllib_ccmp_data *_priv = priv;
93    if (_priv && _priv->tfm)
94        crypto_free_cipher((void *)_priv->tfm);
95    kfree(priv);
96}
97
98
99static inline void xor_block(u8 *b, u8 *a, size_t len)
100{
101    int i;
102    for (i = 0; i < len; i++)
103        b[i] ^= a[i];
104}
105
106
107
108static void ccmp_init_blocks(struct crypto_tfm *tfm,
109                 struct rtllib_hdr_4addr *hdr,
110                 u8 *pn, size_t dlen, u8 *b0, u8 *auth,
111                 u8 *s0)
112{
113    u8 *pos, qc = 0;
114    size_t aad_len;
115    u16 fc;
116    int a4_included, qc_included;
117    u8 aad[2 * AES_BLOCK_LEN];
118
119    fc = le16_to_cpu(hdr->frame_ctl);
120    a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
121               (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS));
122    /*
123    qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
124               (WLAN_FC_GET_STYPE(fc) & 0x08));
125    */
126    qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) &&
127               (WLAN_FC_GET_STYPE(fc) & 0x80));
128    aad_len = 22;
129    if (a4_included)
130        aad_len += 6;
131    if (qc_included) {
132        pos = (u8 *) &hdr->addr4;
133        if (a4_included)
134            pos += 6;
135        qc = *pos & 0x0f;
136        aad_len += 2;
137    }
138    /* CCM Initial Block:
139     * Flag (Include authentication header, M=3 (8-octet MIC),
140     * L=1 (2-octet Dlen))
141     * Nonce: 0x00 | A2 | PN
142     * Dlen */
143    b0[0] = 0x59;
144    b0[1] = qc;
145    memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
146    memcpy(b0 + 8, pn, CCMP_PN_LEN);
147    b0[14] = (dlen >> 8) & 0xff;
148    b0[15] = dlen & 0xff;
149
150    /* AAD:
151     * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
152     * A1 | A2 | A3
153     * SC with bits 4..15 (seq#) masked to zero
154     * A4 (if present)
155     * QC (if present)
156     */
157    pos = (u8 *) hdr;
158    aad[0] = 0; /* aad_len >> 8 */
159    aad[1] = aad_len & 0xff;
160    aad[2] = pos[0] & 0x8f;
161    aad[3] = pos[1] & 0xc7;
162    memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
163    pos = (u8 *) &hdr->seq_ctl;
164    aad[22] = pos[0] & 0x0f;
165    aad[23] = 0; /* all bits masked */
166    memset(aad + 24, 0, 8);
167    if (a4_included)
168        memcpy(aad + 24, hdr->addr4, ETH_ALEN);
169    if (qc_included) {
170        aad[a4_included ? 30 : 24] = qc;
171        /* rest of QC masked */
172    }
173
174    /* Start with the first block and AAD */
175    rtllib_ccmp_aes_encrypt(tfm, b0, auth);
176    xor_block(auth, aad, AES_BLOCK_LEN);
177    rtllib_ccmp_aes_encrypt(tfm, auth, auth);
178    xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
179    rtllib_ccmp_aes_encrypt(tfm, auth, auth);
180    b0[0] &= 0x07;
181    b0[14] = b0[15] = 0;
182    rtllib_ccmp_aes_encrypt(tfm, b0, s0);
183}
184
185
186
187static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
188{
189    struct rtllib_ccmp_data *key = priv;
190    int data_len, i;
191    u8 *pos;
192    struct rtllib_hdr_4addr *hdr;
193    struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
194                    MAX_DEV_ADDR_SIZE);
195    if (skb_headroom(skb) < CCMP_HDR_LEN ||
196        skb_tailroom(skb) < CCMP_MIC_LEN ||
197        skb->len < hdr_len)
198        return -1;
199
200    data_len = skb->len - hdr_len;
201    pos = skb_push(skb, CCMP_HDR_LEN);
202    memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
203    pos += hdr_len;
204
205    i = CCMP_PN_LEN - 1;
206    while (i >= 0) {
207        key->tx_pn[i]++;
208        if (key->tx_pn[i] != 0)
209            break;
210        i--;
211    }
212
213    *pos++ = key->tx_pn[5];
214    *pos++ = key->tx_pn[4];
215    *pos++ = 0;
216    *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
217    *pos++ = key->tx_pn[3];
218    *pos++ = key->tx_pn[2];
219    *pos++ = key->tx_pn[1];
220    *pos++ = key->tx_pn[0];
221
222
223    hdr = (struct rtllib_hdr_4addr *) skb->data;
224    if (!tcb_desc->bHwSec) {
225        int blocks, last, len;
226        u8 *mic;
227        u8 *b0 = key->tx_b0;
228        u8 *b = key->tx_b;
229        u8 *e = key->tx_e;
230        u8 *s0 = key->tx_s0;
231
232        mic = skb_put(skb, CCMP_MIC_LEN);
233
234        ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
235                 b0, b, s0);
236
237        blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
238        last = data_len % AES_BLOCK_LEN;
239
240        for (i = 1; i <= blocks; i++) {
241            len = (i == blocks && last) ? last : AES_BLOCK_LEN;
242            /* Authentication */
243            xor_block(b, pos, len);
244            rtllib_ccmp_aes_encrypt(key->tfm, b, b);
245            /* Encryption, with counter */
246            b0[14] = (i >> 8) & 0xff;
247            b0[15] = i & 0xff;
248            rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
249            xor_block(pos, e, len);
250            pos += len;
251        }
252
253        for (i = 0; i < CCMP_MIC_LEN; i++)
254            mic[i] = b[i] ^ s0[i];
255    }
256    return 0;
257}
258
259
260static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
261{
262    struct rtllib_ccmp_data *key = priv;
263    u8 keyidx, *pos;
264    struct rtllib_hdr_4addr *hdr;
265    struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
266                    MAX_DEV_ADDR_SIZE);
267    u8 pn[6];
268
269    if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
270        key->dot11RSNAStatsCCMPFormatErrors++;
271        return -1;
272    }
273
274    hdr = (struct rtllib_hdr_4addr *) skb->data;
275    pos = skb->data + hdr_len;
276    keyidx = pos[3];
277    if (!(keyidx & (1 << 5))) {
278        if (net_ratelimit()) {
279            printk(KERN_DEBUG "CCMP: received packet without ExtIV"
280                   " flag from %pM\n", hdr->addr2);
281        }
282        key->dot11RSNAStatsCCMPFormatErrors++;
283        return -2;
284    }
285    keyidx >>= 6;
286    if (key->key_idx != keyidx) {
287        printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
288               "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
289        return -6;
290    }
291    if (!key->key_set) {
292        if (net_ratelimit()) {
293            printk(KERN_DEBUG "CCMP: received packet from %pM"
294                   " with keyid=%d that does not have a configured"
295                   " key\n", hdr->addr2, keyidx);
296        }
297        return -3;
298    }
299
300    pn[0] = pos[7];
301    pn[1] = pos[6];
302    pn[2] = pos[5];
303    pn[3] = pos[4];
304    pn[4] = pos[1];
305    pn[5] = pos[0];
306    pos += 8;
307    if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
308        key->dot11RSNAStatsCCMPReplays++;
309        return -4;
310    }
311    if (!tcb_desc->bHwSec) {
312        size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
313                  CCMP_MIC_LEN;
314        u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
315        u8 *b0 = key->rx_b0;
316        u8 *b = key->rx_b;
317        u8 *a = key->rx_a;
318        int i, blocks, last, len;
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            rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
333            xor_block(pos, b, len);
334            /* Authentication */
335            xor_block(a, pos, len);
336            rtllib_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                " %pM\n", 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
360static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
361{
362    struct rtllib_ccmp_data *data = priv;
363    int keyidx;
364    struct crypto_tfm *tfm = data->tfm;
365
366    keyidx = data->key_idx;
367    memset(data, 0, sizeof(*data));
368    data->key_idx = keyidx;
369    data->tfm = tfm;
370    if (len == CCMP_TK_LEN) {
371        memcpy(data->key, key, CCMP_TK_LEN);
372        data->key_set = 1;
373        if (seq) {
374            data->rx_pn[0] = seq[5];
375            data->rx_pn[1] = seq[4];
376            data->rx_pn[2] = seq[3];
377            data->rx_pn[3] = seq[2];
378            data->rx_pn[4] = seq[1];
379            data->rx_pn[5] = seq[0];
380        }
381        crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
382    } else if (len == 0)
383        data->key_set = 0;
384    else
385        return -1;
386
387    return 0;
388}
389
390
391static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
392{
393    struct rtllib_ccmp_data *data = priv;
394
395    if (len < CCMP_TK_LEN)
396        return -1;
397
398    if (!data->key_set)
399        return 0;
400    memcpy(key, data->key, CCMP_TK_LEN);
401
402    if (seq) {
403        seq[0] = data->tx_pn[5];
404        seq[1] = data->tx_pn[4];
405        seq[2] = data->tx_pn[3];
406        seq[3] = data->tx_pn[2];
407        seq[4] = data->tx_pn[1];
408        seq[5] = data->tx_pn[0];
409    }
410
411    return CCMP_TK_LEN;
412}
413
414
415static char *rtllib_ccmp_print_stats(char *p, void *priv)
416{
417    struct rtllib_ccmp_data *ccmp = priv;
418    p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
419             "tx_pn=%pM rx_pn=%pM "
420             "format_errors=%d replays=%d decrypt_errors=%d\n",
421             ccmp->key_idx, ccmp->key_set,
422             ccmp->tx_pn, ccmp->rx_pn,
423             ccmp->dot11RSNAStatsCCMPFormatErrors,
424             ccmp->dot11RSNAStatsCCMPReplays,
425             ccmp->dot11RSNAStatsCCMPDecryptErrors);
426
427    return p;
428}
429
430static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
431    .name = "R-CCMP",
432    .init = rtllib_ccmp_init,
433    .deinit = rtllib_ccmp_deinit,
434    .encrypt_mpdu = rtllib_ccmp_encrypt,
435    .decrypt_mpdu = rtllib_ccmp_decrypt,
436    .encrypt_msdu = NULL,
437    .decrypt_msdu = NULL,
438    .set_key = rtllib_ccmp_set_key,
439    .get_key = rtllib_ccmp_get_key,
440    .print_stats = rtllib_ccmp_print_stats,
441    .extra_mpdu_prefix_len = CCMP_HDR_LEN,
442    .extra_mpdu_postfix_len = CCMP_MIC_LEN,
443    .owner = THIS_MODULE,
444};
445
446
447int __init rtllib_crypto_ccmp_init(void)
448{
449    return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
450}
451
452
453void __exit rtllib_crypto_ccmp_exit(void)
454{
455    lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
456}
457
458module_init(rtllib_crypto_ccmp_init);
459module_exit(rtllib_crypto_ccmp_exit);
460
461MODULE_LICENSE("GPL");
462

Archive Download this file



interactive