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 23 #include "ieee80211.h" 24 25 #include <linux/crypto.h> 26 #include <linux/scatterlist.h> 27 28 MODULE_AUTHOR("Jouni Malinen"); 29 MODULE_DESCRIPTION("Host AP crypt: CCMP"); 30 MODULE_LICENSE("GPL"); 31 32 #define AES_BLOCK_LEN 16 33 #define CCMP_HDR_LEN 8 34 #define CCMP_MIC_LEN 8 35 #define CCMP_TK_LEN 16 36 #define CCMP_PN_LEN 6 37 38 struct ieee80211_ccmp_data { 39 u8 key[CCMP_TK_LEN]; 40 int key_set; 41 42 u8 tx_pn[CCMP_PN_LEN]; 43 u8 rx_pn[CCMP_PN_LEN]; 44 45 u32 dot11RSNAStatsCCMPFormatErrors; 46 u32 dot11RSNAStatsCCMPReplays; 47 u32 dot11RSNAStatsCCMPDecryptErrors; 48 49 int key_idx; 50 51 struct crypto_tfm *tfm; 52 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]; 57 }; 58 59 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm, 60 const u8 pt[16], u8 ct[16]) 61 { 62 crypto_cipher_encrypt_one((void *)tfm, ct, pt); 63 } 64 65 static void *ieee80211_ccmp_init(int key_idx) 66 { 67 struct ieee80211_ccmp_data *priv; 68 69 priv = kzalloc(sizeof(*priv), GFP_ATOMIC); 70 if (priv == NULL) 71 goto fail; 72 priv->key_idx = key_idx; 73 74 priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); 75 if (IS_ERR(priv->tfm)) { 76 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate crypto API aes\n"); 77 priv->tfm = NULL; 78 goto fail; 79 } 80 81 return priv; 82 83 fail: 84 if (priv) { 85 if (priv->tfm) 86 crypto_free_cipher((void *)priv->tfm); 87 kfree(priv); 88 } 89 90 return NULL; 91 } 92 93 94 static void ieee80211_ccmp_deinit(void *priv) 95 { 96 struct ieee80211_ccmp_data *_priv = priv; 97 98 if (_priv && _priv->tfm) 99 crypto_free_cipher((void *)_priv->tfm); 100 kfree(priv); 101 } 102 103 104 static inline void xor_block(u8 *b, u8 *a, size_t len) 105 { 106 int i; 107 108 for (i = 0; i < len; i++) 109 b[i] ^= a[i]; 110 } 111 112 113 114 static void ccmp_init_blocks(struct crypto_tfm *tfm, 115 struct rtl_80211_hdr_4addr *hdr, 116 u8 *pn, size_t dlen, u8 *b0, u8 *auth, 117 u8 *s0) 118 { 119 u8 *pos, qc = 0; 120 size_t aad_len; 121 u16 fc; 122 int a4_included, qc_included; 123 u8 aad[2 * AES_BLOCK_LEN]; 124 125 fc = le16_to_cpu(hdr->frame_ctl); 126 a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) == 127 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)); 128 /* qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) && 129 * (WLAN_FC_GET_STYPE(fc) & 0x08)); 130 */ 131 /* fixed by David :2006.9.6 */ 132 qc_included = (WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) && 133 (WLAN_FC_GET_STYPE(fc) & 0x80); 134 aad_len = 22; 135 if (a4_included) 136 aad_len += 6; 137 if (qc_included) { 138 pos = (u8 *) &hdr->addr4; 139 if (a4_included) 140 pos += 6; 141 qc = *pos & 0x0f; 142 aad_len += 2; 143 } 144 /* CCM Initial Block: 145 * Flag (Include authentication header, M=3 (8-octet MIC), 146 * L=1 (2-octet Dlen)) 147 * Nonce: 0x00 | A2 | PN 148 * Dlen 149 */ 150 b0[0] = 0x59; 151 b0[1] = qc; 152 memcpy(b0 + 2, hdr->addr2, ETH_ALEN); 153 memcpy(b0 + 8, pn, CCMP_PN_LEN); 154 b0[14] = (dlen >> 8) & 0xff; 155 b0[15] = dlen & 0xff; 156 157 /* AAD: 158 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one 159 * A1 | A2 | A3 160 * SC with bits 4..15 (seq#) masked to zero 161 * A4 (if present) 162 * QC (if present) 163 */ 164 pos = (u8 *) hdr; 165 aad[0] = 0; /* aad_len >> 8 */ 166 aad[1] = aad_len & 0xff; 167 aad[2] = pos[0] & 0x8f; 168 aad[3] = pos[1] & 0xc7; 169 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN); 170 pos = (u8 *) &hdr->seq_ctl; 171 aad[22] = pos[0] & 0x0f; 172 aad[23] = 0; /* all bits masked */ 173 memset(aad + 24, 0, 8); 174 if (a4_included) 175 memcpy(aad + 24, hdr->addr4, ETH_ALEN); 176 if (qc_included) { 177 aad[a4_included ? 30 : 24] = qc; 178 /* rest of QC masked */ 179 } 180 181 /* Start with the first block and AAD */ 182 ieee80211_ccmp_aes_encrypt(tfm, b0, auth); 183 xor_block(auth, aad, AES_BLOCK_LEN); 184 ieee80211_ccmp_aes_encrypt(tfm, auth, auth); 185 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN); 186 ieee80211_ccmp_aes_encrypt(tfm, auth, auth); 187 b0[0] &= 0x07; 188 b0[14] = b0[15] = 0; 189 ieee80211_ccmp_aes_encrypt(tfm, b0, s0); 190 } 191 192 193 194 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; 198 u8 *pos; 199 struct rtl_80211_hdr_4addr *hdr; 200 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); 201 202 if (skb_headroom(skb) < CCMP_HDR_LEN || 203 skb_tailroom(skb) < CCMP_MIC_LEN || 204 skb->len < hdr_len) 205 return -1; 206 207 data_len = skb->len - hdr_len; 208 pos = skb_push(skb, CCMP_HDR_LEN); 209 memmove(pos, pos + CCMP_HDR_LEN, hdr_len); 210 pos += hdr_len; 211 /* mic = skb_put(skb, CCMP_MIC_LEN); */ 212 213 i = CCMP_PN_LEN - 1; 214 while (i >= 0) { 215 key->tx_pn[i]++; 216 if (key->tx_pn[i] != 0) 217 break; 218 i--; 219 } 220 221 *pos++ = key->tx_pn[5]; 222 *pos++ = key->tx_pn[4]; 223 *pos++ = 0; 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]; 229 230 231 hdr = (struct rtl_80211_hdr_4addr *) skb->data; 232 if (!tcb_desc->bHwSec) { 233 int blocks, last, len; 234 u8 *mic; 235 u8 *b0 = key->tx_b0; 236 u8 *b = key->tx_b; 237 u8 *e = key->tx_e; 238 u8 *s0 = key->tx_s0; 239 240 /* mic is moved to here by john */ 241 mic = skb_put(skb, CCMP_MIC_LEN); 242 243 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0); 244 245 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); 246 last = data_len % AES_BLOCK_LEN; 247 248 for (i = 1; i <= blocks; i++) { 249 len = (i == blocks && last) ? last : AES_BLOCK_LEN; 250 /* Authentication */ 251 xor_block(b, pos, len); 252 ieee80211_ccmp_aes_encrypt(key->tfm, b, b); 253 /* Encryption, with counter */ 254 b0[14] = (i >> 8) & 0xff; 255 b0[15] = i & 0xff; 256 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e); 257 xor_block(pos, e, len); 258 pos += len; 259 } 260 261 for (i = 0; i < CCMP_MIC_LEN; i++) 262 mic[i] = b[i] ^ s0[i]; 263 } 264 return 0; 265 } 266 267 268 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) 269 { 270 struct ieee80211_ccmp_data *key = priv; 271 u8 keyidx, *pos; 272 struct rtl_80211_hdr_4addr *hdr; 273 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); 274 u8 pn[6]; 275 276 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { 277 key->dot11RSNAStatsCCMPFormatErrors++; 278 return -1; 279 } 280 281 hdr = (struct rtl_80211_hdr_4addr *) skb->data; 282 pos = skb->data + hdr_len; 283 keyidx = pos[3]; 284 if (!(keyidx & (1 << 5))) { 285 if (net_ratelimit()) { 286 printk(KERN_DEBUG "CCMP: received packet without ExtIV flag from %pM\n", 287 hdr->addr2); 288 } 289 key->dot11RSNAStatsCCMPFormatErrors++; 290 return -2; 291 } 292 keyidx >>= 6; 293 if (key->key_idx != keyidx) { 294 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n", 295 key->key_idx, keyidx, priv); 296 return -6; 297 } 298 if (!key->key_set) { 299 if (net_ratelimit()) { 300 printk(KERN_DEBUG "CCMP: received packet from %pM with keyid=%d that does not have a configured key\n", 301 hdr->addr2, keyidx); 302 } 303 return -3; 304 } 305 306 pn[0] = pos[7]; 307 pn[1] = pos[6]; 308 pn[2] = pos[5]; 309 pn[3] = pos[4]; 310 pn[4] = pos[1]; 311 pn[5] = pos[0]; 312 pos += 8; 313 314 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) { 315 if (net_ratelimit()) { 316 printk(KERN_DEBUG "CCMP: replay detected: STA=%pM previous PN %pm received PN %pm\n", 317 hdr->addr2, key->rx_pn, pn); 318 } 319 key->dot11RSNAStatsCCMPReplays++; 320 return -4; 321 } 322 if (!tcb_desc->bHwSec) { 323 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN; 324 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN; 325 u8 *b0 = key->rx_b0; 326 u8 *b = key->rx_b; 327 u8 *a = key->rx_a; 328 int i, blocks, last, len; 329 330 331 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b); 332 xor_block(mic, b, CCMP_MIC_LEN); 333 334 blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); 335 last = data_len % AES_BLOCK_LEN; 336 337 for (i = 1; i <= blocks; i++) { 338 len = (i == blocks && last) ? last : AES_BLOCK_LEN; 339 /* Decrypt, with counter */ 340 b0[14] = (i >> 8) & 0xff; 341 b0[15] = i & 0xff; 342 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b); 343 xor_block(pos, b, len); 344 /* Authentication */ 345 xor_block(a, pos, len); 346 ieee80211_ccmp_aes_encrypt(key->tfm, a, a); 347 pos += len; 348 } 349 350 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) { 351 if (net_ratelimit()) { 352 printk(KERN_DEBUG "CCMP: decrypt failed: STA=%pM\n", 353 hdr->addr2); 354 } 355 key->dot11RSNAStatsCCMPDecryptErrors++; 356 return -5; 357 } 358 359 memcpy(key->rx_pn, pn, CCMP_PN_LEN); 360 } 361 /* Remove hdr and MIC */ 362 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); 363 skb_pull(skb, CCMP_HDR_LEN); 364 skb_trim(skb, skb->len - CCMP_MIC_LEN); 365 366 return keyidx; 367 } 368 369 370 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv) 371 { 372 struct ieee80211_ccmp_data *data = priv; 373 int keyidx; 374 struct crypto_tfm *tfm = data->tfm; 375 376 keyidx = data->key_idx; 377 memset(data, 0, sizeof(*data)); 378 data->key_idx = keyidx; 379 data->tfm = tfm; 380 if (len == CCMP_TK_LEN) { 381 memcpy(data->key, key, CCMP_TK_LEN); 382 data->key_set = 1; 383 if (seq) { 384 data->rx_pn[0] = seq[5]; 385 data->rx_pn[1] = seq[4]; 386 data->rx_pn[2] = seq[3]; 387 data->rx_pn[3] = seq[2]; 388 data->rx_pn[4] = seq[1]; 389 data->rx_pn[5] = seq[0]; 390 } 391 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN); 392 } else if (len == 0) 393 data->key_set = 0; 394 else 395 return -1; 396 397 return 0; 398 } 399 400 401 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv) 402 { 403 struct ieee80211_ccmp_data *data = priv; 404 405 if (len < CCMP_TK_LEN) 406 return -1; 407 408 if (!data->key_set) 409 return 0; 410 memcpy(key, data->key, CCMP_TK_LEN); 411 412 if (seq) { 413 seq[0] = data->tx_pn[5]; 414 seq[1] = data->tx_pn[4]; 415 seq[2] = data->tx_pn[3]; 416 seq[3] = data->tx_pn[2]; 417 seq[4] = data->tx_pn[1]; 418 seq[5] = data->tx_pn[0]; 419 } 420 421 return CCMP_TK_LEN; 422 } 423 424 425 static char *ieee80211_ccmp_print_stats(char *p, void *priv) 426 { 427 struct ieee80211_ccmp_data *ccmp = priv; 428 429 p += sprintf(p, "key[%d] alg=CCMP key_set=%d tx_pn=%pm rx_pn=%pm format_errors=%d replays=%d decrypt_errors=%d\n", 430 ccmp->key_idx, ccmp->key_set, 431 ccmp->tx_pn, ccmp->rx_pn, 432 ccmp->dot11RSNAStatsCCMPFormatErrors, 433 ccmp->dot11RSNAStatsCCMPReplays, 434 ccmp->dot11RSNAStatsCCMPDecryptErrors); 435 436 return p; 437 } 438 439 void ieee80211_ccmp_null(void) 440 { 441 /* printk("============>%s()\n", __func__); */ 442 return; 443 } 444 445 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = { 446 .name = "CCMP", 447 .init = ieee80211_ccmp_init, 448 .deinit = ieee80211_ccmp_deinit, 449 .encrypt_mpdu = ieee80211_ccmp_encrypt, 450 .decrypt_mpdu = ieee80211_ccmp_decrypt, 451 .encrypt_msdu = NULL, 452 .decrypt_msdu = NULL, 453 .set_key = ieee80211_ccmp_set_key, 454 .get_key = ieee80211_ccmp_get_key, 455 .print_stats = ieee80211_ccmp_print_stats, 456 .extra_prefix_len = CCMP_HDR_LEN, 457 .extra_postfix_len = CCMP_MIC_LEN, 458 .owner = THIS_MODULE, 459 }; 460 461 int __init ieee80211_crypto_ccmp_init(void) 462 { 463 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp); 464 } 465 466 void __exit ieee80211_crypto_ccmp_exit(void) 467 { 468 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp); 469 } 470