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 pr_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 94 if (_priv && _priv->tfm) 95 crypto_free_cipher((void *)_priv->tfm); 96 kfree(priv); 97} 98 99 100static inline void xor_block(u8 *b, u8 *a, size_t len) 101{ 102 int i; 103 104 for (i = 0; i < len; i++) 105 b[i] ^= a[i]; 106} 107 108 109 110static void ccmp_init_blocks(struct crypto_tfm *tfm, 111 struct rtllib_hdr_4addr *hdr, 112 u8 *pn, size_t dlen, u8 *b0, u8 *auth, 113 u8 *s0) 114{ 115 u8 *pos, qc = 0; 116 size_t aad_len; 117 u16 fc; 118 int a4_included, qc_included; 119 u8 aad[2 * AES_BLOCK_LEN]; 120 121 fc = le16_to_cpu(hdr->frame_ctl); 122 a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) == 123 (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)); 124 /* 125 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) && 126 (WLAN_FC_GET_STYPE(fc) & 0x08)); 127 */ 128 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) && 129 (WLAN_FC_GET_STYPE(fc) & 0x80)); 130 aad_len = 22; 131 if (a4_included) 132 aad_len += 6; 133 if (qc_included) { 134 pos = (u8 *) &hdr->addr4; 135 if (a4_included) 136 pos += 6; 137 qc = *pos & 0x0f; 138 aad_len += 2; 139 } 140 /* CCM Initial Block: 141 * Flag (Include authentication header, M=3 (8-octet MIC), 142 * L=1 (2-octet Dlen)) 143 * Nonce: 0x00 | A2 | PN 144 * Dlen */ 145 b0[0] = 0x59; 146 b0[1] = qc; 147 memcpy(b0 + 2, hdr->addr2, ETH_ALEN); 148 memcpy(b0 + 8, pn, CCMP_PN_LEN); 149 b0[14] = (dlen >> 8) & 0xff; 150 b0[15] = dlen & 0xff; 151 152 /* AAD: 153 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one 154 * A1 | A2 | A3 155 * SC with bits 4..15 (seq#) masked to zero 156 * A4 (if present) 157 * QC (if present) 158 */ 159 pos = (u8 *) hdr; 160 aad[0] = 0; /* aad_len >> 8 */ 161 aad[1] = aad_len & 0xff; 162 aad[2] = pos[0] & 0x8f; 163 aad[3] = pos[1] & 0xc7; 164 memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN); 165 pos = (u8 *) &hdr->seq_ctl; 166 aad[22] = pos[0] & 0x0f; 167 aad[23] = 0; /* all bits masked */ 168 memset(aad + 24, 0, 8); 169 if (a4_included) 170 memcpy(aad + 24, hdr->addr4, ETH_ALEN); 171 if (qc_included) { 172 aad[a4_included ? 30 : 24] = qc; 173 /* rest of QC masked */ 174 } 175 176 /* Start with the first block and AAD */ 177 rtllib_ccmp_aes_encrypt(tfm, b0, auth); 178 xor_block(auth, aad, AES_BLOCK_LEN); 179 rtllib_ccmp_aes_encrypt(tfm, auth, auth); 180 xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN); 181 rtllib_ccmp_aes_encrypt(tfm, auth, auth); 182 b0[0] &= 0x07; 183 b0[14] = b0[15] = 0; 184 rtllib_ccmp_aes_encrypt(tfm, b0, s0); 185} 186 187 188 189static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv) 190{ 191 struct rtllib_ccmp_data *key = priv; 192 int data_len, i; 193 u8 *pos; 194 struct rtllib_hdr_4addr *hdr; 195 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 196 MAX_DEV_ADDR_SIZE); 197 if (skb_headroom(skb) < CCMP_HDR_LEN || 198 skb_tailroom(skb) < CCMP_MIC_LEN || 199 skb->len < hdr_len) 200 return -1; 201 202 data_len = skb->len - hdr_len; 203 pos = skb_push(skb, CCMP_HDR_LEN); 204 memmove(pos, pos + CCMP_HDR_LEN, hdr_len); 205 pos += hdr_len; 206 207 i = CCMP_PN_LEN - 1; 208 while (i >= 0) { 209 key->tx_pn[i]++; 210 if (key->tx_pn[i] != 0) 211 break; 212 i--; 213 } 214 215 *pos++ = key->tx_pn[5]; 216 *pos++ = key->tx_pn[4]; 217 *pos++ = 0; 218 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */; 219 *pos++ = key->tx_pn[3]; 220 *pos++ = key->tx_pn[2]; 221 *pos++ = key->tx_pn[1]; 222 *pos++ = key->tx_pn[0]; 223 224 225 hdr = (struct rtllib_hdr_4addr *) skb->data; 226 if (!tcb_desc->bHwSec) { 227 int blocks, last, len; 228 u8 *mic; 229 u8 *b0 = key->tx_b0; 230 u8 *b = key->tx_b; 231 u8 *e = key->tx_e; 232 u8 *s0 = key->tx_s0; 233 234 mic = skb_put(skb, CCMP_MIC_LEN); 235 236 ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, 237 b0, b, s0); 238 239 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; 240 last = data_len % AES_BLOCK_LEN; 241 242 for (i = 1; i <= blocks; i++) { 243 len = (i == blocks && last) ? last : AES_BLOCK_LEN; 244 /* Authentication */ 245 xor_block(b, pos, len); 246 rtllib_ccmp_aes_encrypt(key->tfm, b, b); 247 /* Encryption, with counter */ 248 b0[14] = (i >> 8) & 0xff; 249 b0[15] = i & 0xff; 250 rtllib_ccmp_aes_encrypt(key->tfm, b0, e); 251 xor_block(pos, e, len); 252 pos += len; 253 } 254 255 for (i = 0; i < CCMP_MIC_LEN; i++) 256 mic[i] = b[i] ^ s0[i]; 257 } 258 return 0; 259} 260 261 262static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) 263{ 264 struct rtllib_ccmp_data *key = priv; 265 u8 keyidx, *pos; 266 struct rtllib_hdr_4addr *hdr; 267 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 268 MAX_DEV_ADDR_SIZE); 269 u8 pn[6]; 270 271 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { 272 key->dot11RSNAStatsCCMPFormatErrors++; 273 return -1; 274 } 275 276 hdr = (struct rtllib_hdr_4addr *) skb->data; 277 pos = skb->data + hdr_len; 278 keyidx = pos[3]; 279 if (!(keyidx & (1 << 5))) { 280 if (net_ratelimit()) { 281 pr_debug("CCMP: received packet without ExtIV" 282 " flag from %pM\n", hdr->addr2); 283 } 284 key->dot11RSNAStatsCCMPFormatErrors++; 285 return -2; 286 } 287 keyidx >>= 6; 288 if (key->key_idx != keyidx) { 289 pr_debug("CCMP: RX tkey->key_idx=%d frame " 290 "keyidx=%d priv=%p\n", key->key_idx, keyidx, priv); 291 return -6; 292 } 293 if (!key->key_set) { 294 if (net_ratelimit()) { 295 pr_debug("CCMP: received packet from %pM" 296 " with keyid=%d that does not have a configured" 297 " key\n", hdr->addr2, keyidx); 298 } 299 return -3; 300 } 301 302 pn[0] = pos[7]; 303 pn[1] = pos[6]; 304 pn[2] = pos[5]; 305 pn[3] = pos[4]; 306 pn[4] = pos[1]; 307 pn[5] = pos[0]; 308 pos += 8; 309 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) { 310 key->dot11RSNAStatsCCMPReplays++; 311 return -4; 312 } 313 if (!tcb_desc->bHwSec) { 314 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - 315 CCMP_MIC_LEN; 316 u8 *mic = skb->data + skb->len - CCMP_MIC_LEN; 317 u8 *b0 = key->rx_b0; 318 u8 *b = key->rx_b; 319 u8 *a = key->rx_a; 320 int i, blocks, last, len; 321 322 323 ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b); 324 xor_block(mic, b, CCMP_MIC_LEN); 325 326 blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN; 327 last = data_len % AES_BLOCK_LEN; 328 329 for (i = 1; i <= blocks; i++) { 330 len = (i == blocks && last) ? last : AES_BLOCK_LEN; 331 /* Decrypt, with counter */ 332 b0[14] = (i >> 8) & 0xff; 333 b0[15] = i & 0xff; 334 rtllib_ccmp_aes_encrypt(key->tfm, b0, b); 335 xor_block(pos, b, len); 336 /* Authentication */ 337 xor_block(a, pos, len); 338 rtllib_ccmp_aes_encrypt(key->tfm, a, a); 339 pos += len; 340 } 341 342 if (memcmp(mic, a, CCMP_MIC_LEN) != 0) { 343 if (net_ratelimit()) { 344 pr_debug("CCMP: decrypt failed: STA=" 345 " %pM\n", hdr->addr2); 346 } 347 key->dot11RSNAStatsCCMPDecryptErrors++; 348 return -5; 349 } 350 351 memcpy(key->rx_pn, pn, CCMP_PN_LEN); 352 } 353 /* Remove hdr and MIC */ 354 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); 355 skb_pull(skb, CCMP_HDR_LEN); 356 skb_trim(skb, skb->len - CCMP_MIC_LEN); 357 358 return keyidx; 359} 360 361 362static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv) 363{ 364 struct rtllib_ccmp_data *data = priv; 365 int keyidx; 366 struct crypto_tfm *tfm = data->tfm; 367 368 keyidx = data->key_idx; 369 memset(data, 0, sizeof(*data)); 370 data->key_idx = keyidx; 371 data->tfm = tfm; 372 if (len == CCMP_TK_LEN) { 373 memcpy(data->key, key, CCMP_TK_LEN); 374 data->key_set = 1; 375 if (seq) { 376 data->rx_pn[0] = seq[5]; 377 data->rx_pn[1] = seq[4]; 378 data->rx_pn[2] = seq[3]; 379 data->rx_pn[3] = seq[2]; 380 data->rx_pn[4] = seq[1]; 381 data->rx_pn[5] = seq[0]; 382 } 383 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN); 384 } else if (len == 0) 385 data->key_set = 0; 386 else 387 return -1; 388 389 return 0; 390} 391 392 393static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv) 394{ 395 struct rtllib_ccmp_data *data = priv; 396 397 if (len < CCMP_TK_LEN) 398 return -1; 399 400 if (!data->key_set) 401 return 0; 402 memcpy(key, data->key, CCMP_TK_LEN); 403 404 if (seq) { 405 seq[0] = data->tx_pn[5]; 406 seq[1] = data->tx_pn[4]; 407 seq[2] = data->tx_pn[3]; 408 seq[3] = data->tx_pn[2]; 409 seq[4] = data->tx_pn[1]; 410 seq[5] = data->tx_pn[0]; 411 } 412 413 return CCMP_TK_LEN; 414} 415 416 417static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv) 418{ 419 struct rtllib_ccmp_data *ccmp = priv; 420 421 seq_printf(m, 422 "key[%d] alg=CCMP key_set=%d " 423 "tx_pn=%pM rx_pn=%pM " 424 "format_errors=%d replays=%d decrypt_errors=%d\n", 425 ccmp->key_idx, ccmp->key_set, 426 ccmp->tx_pn, ccmp->rx_pn, 427 ccmp->dot11RSNAStatsCCMPFormatErrors, 428 ccmp->dot11RSNAStatsCCMPReplays, 429 ccmp->dot11RSNAStatsCCMPDecryptErrors); 430} 431 432static struct lib80211_crypto_ops rtllib_crypt_ccmp = { 433 .name = "R-CCMP", 434 .init = rtllib_ccmp_init, 435 .deinit = rtllib_ccmp_deinit, 436 .encrypt_mpdu = rtllib_ccmp_encrypt, 437 .decrypt_mpdu = rtllib_ccmp_decrypt, 438 .encrypt_msdu = NULL, 439 .decrypt_msdu = NULL, 440 .set_key = rtllib_ccmp_set_key, 441 .get_key = rtllib_ccmp_get_key, 442 .print_stats = rtllib_ccmp_print_stats, 443 .extra_mpdu_prefix_len = CCMP_HDR_LEN, 444 .extra_mpdu_postfix_len = CCMP_MIC_LEN, 445 .owner = THIS_MODULE, 446}; 447 448 449static int __init rtllib_crypto_ccmp_init(void) 450{ 451 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp); 452} 453 454 455static void __exit rtllib_crypto_ccmp_exit(void) 456{ 457 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp); 458} 459 460module_init(rtllib_crypto_ccmp_init); 461module_exit(rtllib_crypto_ccmp_exit); 462 463MODULE_LICENSE("GPL"); 464