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/version.h> 13#include <linux/module.h> 14#include <linux/init.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 <asm/string.h> 22#include <linux/wireless.h> 23 24#include "ieee80211.h" 25 26#include <linux/crypto.h> 27#include <linux/scatterlist.h> 28 29MODULE_AUTHOR("Jouni Malinen"); 30MODULE_DESCRIPTION("Host AP crypt: CCMP"); 31MODULE_LICENSE("GPL"); 32 33#define AES_BLOCK_LEN 16 34#define CCMP_HDR_LEN 8 35#define CCMP_MIC_LEN 8 36#define CCMP_TK_LEN 16 37#define CCMP_PN_LEN 6 38 39struct ieee80211_ccmp_data { 40 u8 key[CCMP_TK_LEN]; 41 int key_set; 42 43 u8 tx_pn[CCMP_PN_LEN]; 44 u8 rx_pn[CCMP_PN_LEN]; 45 46 u32 dot11RSNAStatsCCMPFormatErrors; 47 u32 dot11RSNAStatsCCMPReplays; 48 u32 dot11RSNAStatsCCMPDecryptErrors; 49 50 int key_idx; 51 52 struct crypto_tfm *tfm; 53 54 /* scratch buffers for virt_to_page() (crypto API) */ 55 u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN], 56 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN]; 57 u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN]; 58}; 59 60void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm, 61 const u8 pt[16], u8 ct[16]) 62{ 63 crypto_cipher_encrypt_one((void*)tfm, ct, pt); 64} 65 66static void * ieee80211_ccmp_init(int key_idx) 67{ 68 struct ieee80211_ccmp_data *priv; 69 70 priv = kzalloc(sizeof(*priv), GFP_ATOMIC); 71 if (priv == NULL) 72 goto fail; 73 priv->key_idx = key_idx; 74 75 priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC); 76 if (IS_ERR(priv->tfm)) { 77 printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate " 78 "crypto API aes\n"); 79 priv->tfm = NULL; 80 goto fail; 81 } 82 83 return priv; 84 85fail: 86 if (priv) { 87 if (priv->tfm) 88 crypto_free_cipher((void*)priv->tfm); 89 kfree(priv); 90 } 91 92 return NULL; 93} 94 95 96static void ieee80211_ccmp_deinit(void *priv) 97{ 98 struct ieee80211_ccmp_data *_priv = priv; 99 100 if (_priv && _priv->tfm) 101 crypto_free_cipher((void*)_priv->tfm); 102 kfree(priv); 103} 104 105 106static inline void xor_block(u8 *b, u8 *a, size_t len) 107{ 108 int i; 109 for (i = 0; i < len; i++) 110 b[i] ^= a[i]; 111} 112 113 114 115static void ccmp_init_blocks(struct crypto_tfm *tfm, 116 struct ieee80211_hdr_4addr *hdr, 117 u8 *pn, size_t dlen, u8 *b0, u8 *auth, 118 u8 *s0) 119{ 120 u8 *pos, qc = 0; 121 size_t aad_len; 122 u16 fc; 123 int a4_included, qc_included; 124 u8 aad[2 * AES_BLOCK_LEN]; 125 126 fc = le16_to_cpu(hdr->frame_ctl); 127 a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) == 128 (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)); 129 /* 130 qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) && 131 (WLAN_FC_GET_STYPE(fc) & 0x08)); 132 */ 133 qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) && 134 (WLAN_FC_GET_STYPE(fc) & 0x80)); 135 aad_len = 22; 136 if (a4_included) 137 aad_len += 6; 138 if (qc_included) { 139 pos = (u8 *) &hdr->addr4; 140 if (a4_included) 141 pos += 6; 142 qc = *pos & 0x0f; 143 aad_len += 2; 144 } 145 /* CCM Initial Block: 146 * Flag (Include authentication header, M=3 (8-octet MIC), 147 * L=1 (2-octet Dlen)) 148 * Nonce: 0x00 | A2 | PN 149 * Dlen */ 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 194static 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 ieee80211_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; 211 212 i = CCMP_PN_LEN - 1; 213 while (i >= 0) { 214 key->tx_pn[i]++; 215 if (key->tx_pn[i] != 0) 216 break; 217 i--; 218 } 219 220 *pos++ = key->tx_pn[5]; 221 *pos++ = key->tx_pn[4]; 222 *pos++ = 0; 223 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */; 224 *pos++ = key->tx_pn[3]; 225 *pos++ = key->tx_pn[2]; 226 *pos++ = key->tx_pn[1]; 227 *pos++ = key->tx_pn[0]; 228 229 230 hdr = (struct ieee80211_hdr_4addr *) skb->data; 231 if (!tcb_desc->bHwSec) 232 { 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 = skb_put(skb, CCMP_MIC_LEN); 241 242 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0); 243 244 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; 245 last = data_len % AES_BLOCK_LEN; 246 247 for (i = 1; i <= blocks; i++) { 248 len = (i == blocks && last) ? last : AES_BLOCK_LEN; 249 /* Authentication */ 250 xor_block(b, pos, len); 251 ieee80211_ccmp_aes_encrypt(key->tfm, b, b); 252 /* Encryption, with counter */ 253 b0[14] = (i >> 8) & 0xff; 254 b0[15] = i & 0xff; 255 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e); 256 xor_block(pos, e, len); 257 pos += len; 258 } 259 260 for (i = 0; i < CCMP_MIC_LEN; i++) 261 mic[i] = b[i] ^ s0[i]; 262 } 263 return 0; 264} 265 266 267static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) 268{ 269 struct ieee80211_ccmp_data *key = priv; 270 u8 keyidx, *pos; 271 struct ieee80211_hdr_4addr *hdr; 272 cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); 273 u8 pn[6]; 274 275 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { 276 key->dot11RSNAStatsCCMPFormatErrors++; 277 return -1; 278 } 279 280 hdr = (struct ieee80211_hdr_4addr *) skb->data; 281 pos = skb->data + hdr_len; 282 keyidx = pos[3]; 283 if (!(keyidx & (1 << 5))) { 284 if (net_ratelimit()) { 285 printk(KERN_DEBUG "CCMP: received packet without ExtIV" 286 " flag from %pM\n", hdr->addr2); 287 } 288 key->dot11RSNAStatsCCMPFormatErrors++; 289 return -2; 290 } 291 keyidx >>= 6; 292 if (key->key_idx != keyidx) { 293 printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame " 294 "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv); 295 return -6; 296 } 297 if (!key->key_set) { 298 if (net_ratelimit()) { 299 printk(KERN_DEBUG "CCMP: received packet from %pM" 300 " with keyid=%d that does not have a configured" 301 " key\n", 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" 317 " previous PN %pm received PN %pm\n", 318 hdr->addr2, key->rx_pn, pn); 319 } 320 key->dot11RSNAStatsCCMPReplays++; 321 return -4; 322 } 323 if (!tcb_desc->bHwSec) 324 { 325 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN; 326 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN; 327 u8 *b0 = key->rx_b0; 328 u8 *b = key->rx_b; 329 u8 *a = key->rx_a; 330 int i, blocks, last, len; 331 332 333 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b); 334 xor_block(mic, b, CCMP_MIC_LEN); 335 336 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; 337 last = data_len % AES_BLOCK_LEN; 338 339 for (i = 1; i <= blocks; i++) { 340 len = (i == blocks && last) ? last : AES_BLOCK_LEN; 341 /* Decrypt, with counter */ 342 b0[14] = (i >> 8) & 0xff; 343 b0[15] = i & 0xff; 344 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b); 345 xor_block(pos, b, len); 346 /* Authentication */ 347 xor_block(a, pos, len); 348 ieee80211_ccmp_aes_encrypt(key->tfm, a, a); 349 pos += len; 350 } 351 352 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) { 353 if (net_ratelimit()) { 354 printk(KERN_DEBUG "CCMP: decrypt failed: STA=" 355 "%pM\n", hdr->addr2); 356 } 357 key->dot11RSNAStatsCCMPDecryptErrors++; 358 return -5; 359 } 360 361 memcpy(key->rx_pn, pn, CCMP_PN_LEN); 362 } 363 /* Remove hdr and MIC */ 364 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); 365 skb_pull(skb, CCMP_HDR_LEN); 366 skb_trim(skb, skb->len - CCMP_MIC_LEN); 367 368 return keyidx; 369} 370 371 372static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv) 373{ 374 struct ieee80211_ccmp_data *data = priv; 375 int keyidx; 376 struct crypto_tfm *tfm = data->tfm; 377 378 keyidx = data->key_idx; 379 memset(data, 0, sizeof(*data)); 380 data->key_idx = keyidx; 381 data->tfm = tfm; 382 if (len == CCMP_TK_LEN) { 383 memcpy(data->key, key, CCMP_TK_LEN); 384 data->key_set = 1; 385 if (seq) { 386 data->rx_pn[0] = seq[5]; 387 data->rx_pn[1] = seq[4]; 388 data->rx_pn[2] = seq[3]; 389 data->rx_pn[3] = seq[2]; 390 data->rx_pn[4] = seq[1]; 391 data->rx_pn[5] = seq[0]; 392 } 393 crypto_cipher_setkey((void*)data->tfm, data->key, CCMP_TK_LEN); 394 } else if (len == 0) 395 data->key_set = 0; 396 else 397 return -1; 398 399 return 0; 400} 401 402 403static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv) 404{ 405 struct ieee80211_ccmp_data *data = priv; 406 407 if (len < CCMP_TK_LEN) 408 return -1; 409 410 if (!data->key_set) 411 return 0; 412 memcpy(key, data->key, CCMP_TK_LEN); 413 414 if (seq) { 415 seq[0] = data->tx_pn[5]; 416 seq[1] = data->tx_pn[4]; 417 seq[2] = data->tx_pn[3]; 418 seq[3] = data->tx_pn[2]; 419 seq[4] = data->tx_pn[1]; 420 seq[5] = data->tx_pn[0]; 421 } 422 423 return CCMP_TK_LEN; 424} 425 426 427static char * ieee80211_ccmp_print_stats(char *p, void *priv) 428{ 429 struct ieee80211_ccmp_data *ccmp = priv; 430 p += sprintf(p, "key[%d] alg=CCMP key_set=%d " 431 "tx_pn=%pm rx_pn=%pm " 432 "format_errors=%d replays=%d decrypt_errors=%d\n", 433 ccmp->key_idx, ccmp->key_set, 434 ccmp->tx_pn, ccmp->rx_pn, 435 ccmp->dot11RSNAStatsCCMPFormatErrors, 436 ccmp->dot11RSNAStatsCCMPReplays, 437 ccmp->dot11RSNAStatsCCMPDecryptErrors); 438 439 return p; 440} 441 442void ieee80211_ccmp_null(void) 443{ 444 return; 445} 446 447static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = { 448 .name = "CCMP", 449 .init = ieee80211_ccmp_init, 450 .deinit = ieee80211_ccmp_deinit, 451 .encrypt_mpdu = ieee80211_ccmp_encrypt, 452 .decrypt_mpdu = ieee80211_ccmp_decrypt, 453 .encrypt_msdu = NULL, 454 .decrypt_msdu = NULL, 455 .set_key = ieee80211_ccmp_set_key, 456 .get_key = ieee80211_ccmp_get_key, 457 .print_stats = ieee80211_ccmp_print_stats, 458 .extra_prefix_len = CCMP_HDR_LEN, 459 .extra_postfix_len = CCMP_MIC_LEN, 460 .owner = THIS_MODULE, 461}; 462 463int __init ieee80211_crypto_ccmp_init(void) 464{ 465 return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp); 466} 467 468void ieee80211_crypto_ccmp_exit(void) 469{ 470 ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp); 471} 472