1 // SPDX-License-Identifier: GPL-2.0 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 7 #include <linux/module.h> 8 #include <linux/init.h> 9 #include <linux/slab.h> 10 #include <linux/random.h> 11 #include <linux/skbuff.h> 12 #include <linux/netdevice.h> 13 #include <linux/if_ether.h> 14 #include <linux/if_arp.h> 15 #include <linux/string.h> 16 #include <linux/wireless.h> 17 #include "rtllib.h" 18 19 #include <linux/crypto.h> 20 #include <crypto/aead.h> 21 22 #include <linux/scatterlist.h> 23 24 #define AES_BLOCK_LEN 16 25 #define CCMP_HDR_LEN 8 26 #define CCMP_MIC_LEN 8 27 #define CCMP_TK_LEN 16 28 #define CCMP_PN_LEN 6 29 30 struct rtllib_ccmp_data { 31 u8 key[CCMP_TK_LEN]; 32 int key_set; 33 34 u8 tx_pn[CCMP_PN_LEN]; 35 u8 rx_pn[CCMP_PN_LEN]; 36 37 u32 dot11RSNAStatsCCMPFormatErrors; 38 u32 dot11RSNAStatsCCMPReplays; 39 u32 dot11RSNAStatsCCMPDecryptErrors; 40 41 int key_idx; 42 43 struct crypto_aead *tfm; 44 45 /* scratch buffers for virt_to_page() (crypto API) */ 46 u8 tx_aad[2 * AES_BLOCK_LEN]; 47 u8 rx_aad[2 * AES_BLOCK_LEN]; 48 }; 49 50 static void *rtllib_ccmp_init(int key_idx) 51 { 52 struct rtllib_ccmp_data *priv; 53 54 priv = kzalloc(sizeof(*priv), GFP_ATOMIC); 55 if (priv == NULL) 56 goto fail; 57 priv->key_idx = key_idx; 58 59 priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC); 60 if (IS_ERR(priv->tfm)) { 61 pr_debug("Could not allocate crypto API aes\n"); 62 priv->tfm = NULL; 63 goto fail; 64 } 65 return priv; 66 67 fail: 68 if (priv) { 69 if (priv->tfm) 70 crypto_free_aead(priv->tfm); 71 kfree(priv); 72 } 73 74 return NULL; 75 } 76 77 78 static void rtllib_ccmp_deinit(void *priv) 79 { 80 struct rtllib_ccmp_data *_priv = priv; 81 82 if (_priv && _priv->tfm) 83 crypto_free_aead(_priv->tfm); 84 kfree(priv); 85 } 86 87 88 static int ccmp_init_iv_and_aad(struct rtllib_hdr_4addr *hdr, 89 u8 *pn, u8 *iv, u8 *aad) 90 { 91 u8 *pos, qc = 0; 92 size_t aad_len; 93 u16 fc; 94 int a4_included, qc_included; 95 96 fc = le16_to_cpu(hdr->frame_ctl); 97 a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) == 98 (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)); 99 100 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) && 101 (WLAN_FC_GET_STYPE(fc) & 0x80)); 102 aad_len = 22; 103 if (a4_included) 104 aad_len += 6; 105 if (qc_included) { 106 pos = (u8 *) &hdr->addr4; 107 if (a4_included) 108 pos += 6; 109 qc = *pos & 0x0f; 110 aad_len += 2; 111 } 112 /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC 113 * mode authentication are not allowed to collide, yet both are derived 114 * from the same vector. We only set L := 1 here to indicate that the 115 * data size can be represented in (L+1) bytes. The CCM layer will take 116 * care of storing the data length in the top (L+1) bytes and setting 117 * and clearing the other bits as is required to derive the two IVs. 118 */ 119 iv[0] = 0x1; 120 121 /* Nonce: QC | A2 | PN */ 122 iv[1] = qc; 123 memcpy(iv + 2, hdr->addr2, ETH_ALEN); 124 memcpy(iv + 8, pn, CCMP_PN_LEN); 125 126 /* AAD: 127 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one 128 * A1 | A2 | A3 129 * SC with bits 4..15 (seq#) masked to zero 130 * A4 (if present) 131 * QC (if present) 132 */ 133 pos = (u8 *) hdr; 134 aad[0] = pos[0] & 0x8f; 135 aad[1] = pos[1] & 0xc7; 136 memcpy(&aad[2], &hdr->addr1, ETH_ALEN); 137 memcpy(&aad[8], &hdr->addr2, ETH_ALEN); 138 memcpy(&aad[14], &hdr->addr3, ETH_ALEN); 139 pos = (u8 *) &hdr->seq_ctl; 140 aad[20] = pos[0] & 0x0f; 141 aad[21] = 0; /* all bits masked */ 142 memset(aad + 22, 0, 8); 143 if (a4_included) 144 memcpy(aad + 22, hdr->addr4, ETH_ALEN); 145 if (qc_included) { 146 aad[a4_included ? 28 : 22] = qc; 147 /* rest of QC masked */ 148 } 149 150 return aad_len; 151 } 152 153 154 155 static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv) 156 { 157 struct rtllib_ccmp_data *key = priv; 158 int i; 159 u8 *pos; 160 struct rtllib_hdr_4addr *hdr; 161 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 162 MAX_DEV_ADDR_SIZE); 163 if (skb_headroom(skb) < CCMP_HDR_LEN || 164 skb_tailroom(skb) < CCMP_MIC_LEN || 165 skb->len < hdr_len) 166 return -1; 167 168 pos = skb_push(skb, CCMP_HDR_LEN); 169 memmove(pos, pos + CCMP_HDR_LEN, hdr_len); 170 pos += hdr_len; 171 172 i = CCMP_PN_LEN - 1; 173 while (i >= 0) { 174 key->tx_pn[i]++; 175 if (key->tx_pn[i] != 0) 176 break; 177 i--; 178 } 179 180 *pos++ = key->tx_pn[5]; 181 *pos++ = key->tx_pn[4]; 182 *pos++ = 0; 183 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */; 184 *pos++ = key->tx_pn[3]; 185 *pos++ = key->tx_pn[2]; 186 *pos++ = key->tx_pn[1]; 187 *pos++ = key->tx_pn[0]; 188 189 hdr = (struct rtllib_hdr_4addr *) skb->data; 190 if (!tcb_desc->bHwSec) { 191 struct aead_request *req; 192 struct scatterlist sg[2]; 193 u8 *aad = key->tx_aad; 194 u8 iv[AES_BLOCK_LEN]; 195 int aad_len, ret; 196 int data_len = skb->len - hdr_len - CCMP_HDR_LEN; 197 198 req = aead_request_alloc(key->tfm, GFP_ATOMIC); 199 if (!req) 200 return -ENOMEM; 201 202 aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad); 203 204 skb_put(skb, CCMP_MIC_LEN); 205 sg_init_table(sg, 2); 206 sg_set_buf(&sg[0], aad, aad_len); 207 sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN, 208 data_len + CCMP_MIC_LEN); 209 210 aead_request_set_callback(req, 0, NULL, NULL); 211 aead_request_set_ad(req, aad_len); 212 aead_request_set_crypt(req, sg, sg, data_len, iv); 213 214 ret = crypto_aead_encrypt(req); 215 aead_request_free(req); 216 217 return ret; 218 } 219 220 return 0; 221 } 222 223 224 static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) 225 { 226 struct rtllib_ccmp_data *key = priv; 227 u8 keyidx, *pos; 228 struct rtllib_hdr_4addr *hdr; 229 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 230 MAX_DEV_ADDR_SIZE); 231 u8 pn[6]; 232 233 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { 234 key->dot11RSNAStatsCCMPFormatErrors++; 235 return -1; 236 } 237 238 hdr = (struct rtllib_hdr_4addr *) skb->data; 239 pos = skb->data + hdr_len; 240 keyidx = pos[3]; 241 if (!(keyidx & (1 << 5))) { 242 if (net_ratelimit()) { 243 pr_debug("CCMP: received packet without ExtIV flag from %pM\n", 244 hdr->addr2); 245 } 246 key->dot11RSNAStatsCCMPFormatErrors++; 247 return -2; 248 } 249 keyidx >>= 6; 250 if (key->key_idx != keyidx) { 251 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n", 252 key->key_idx, keyidx, priv); 253 return -6; 254 } 255 if (!key->key_set) { 256 if (net_ratelimit()) { 257 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n", 258 hdr->addr2, keyidx); 259 } 260 return -3; 261 } 262 263 pn[0] = pos[7]; 264 pn[1] = pos[6]; 265 pn[2] = pos[5]; 266 pn[3] = pos[4]; 267 pn[4] = pos[1]; 268 pn[5] = pos[0]; 269 pos += 8; 270 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) { 271 key->dot11RSNAStatsCCMPReplays++; 272 return -4; 273 } 274 if (!tcb_desc->bHwSec) { 275 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN; 276 struct aead_request *req; 277 struct scatterlist sg[2]; 278 u8 *aad = key->rx_aad; 279 u8 iv[AES_BLOCK_LEN]; 280 int aad_len, ret; 281 282 req = aead_request_alloc(key->tfm, GFP_ATOMIC); 283 if (!req) 284 return -ENOMEM; 285 286 aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad); 287 288 sg_init_table(sg, 2); 289 sg_set_buf(&sg[0], aad, aad_len); 290 sg_set_buf(&sg[1], pos, data_len); 291 292 aead_request_set_callback(req, 0, NULL, NULL); 293 aead_request_set_ad(req, aad_len); 294 aead_request_set_crypt(req, sg, sg, data_len, iv); 295 296 ret = crypto_aead_decrypt(req); 297 aead_request_free(req); 298 299 if (ret) { 300 if (net_ratelimit()) { 301 pr_debug("CCMP: decrypt failed: STA= %pM\n", 302 hdr->addr2); 303 } 304 key->dot11RSNAStatsCCMPDecryptErrors++; 305 return -5; 306 } 307 308 memcpy(key->rx_pn, pn, CCMP_PN_LEN); 309 } 310 /* Remove hdr and MIC */ 311 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); 312 skb_pull(skb, CCMP_HDR_LEN); 313 skb_trim(skb, skb->len - CCMP_MIC_LEN); 314 315 return keyidx; 316 } 317 318 319 static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv) 320 { 321 struct rtllib_ccmp_data *data = priv; 322 int keyidx; 323 struct crypto_aead *tfm = data->tfm; 324 325 keyidx = data->key_idx; 326 memset(data, 0, sizeof(*data)); 327 data->key_idx = keyidx; 328 data->tfm = tfm; 329 if (len == CCMP_TK_LEN) { 330 memcpy(data->key, key, CCMP_TK_LEN); 331 data->key_set = 1; 332 if (seq) { 333 data->rx_pn[0] = seq[5]; 334 data->rx_pn[1] = seq[4]; 335 data->rx_pn[2] = seq[3]; 336 data->rx_pn[3] = seq[2]; 337 data->rx_pn[4] = seq[1]; 338 data->rx_pn[5] = seq[0]; 339 } 340 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) || 341 crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN)) 342 return -1; 343 } else if (len == 0) { 344 data->key_set = 0; 345 } else { 346 return -1; 347 } 348 349 return 0; 350 } 351 352 353 static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv) 354 { 355 struct rtllib_ccmp_data *data = priv; 356 357 if (len < CCMP_TK_LEN) 358 return -1; 359 360 if (!data->key_set) 361 return 0; 362 memcpy(key, data->key, CCMP_TK_LEN); 363 364 if (seq) { 365 seq[0] = data->tx_pn[5]; 366 seq[1] = data->tx_pn[4]; 367 seq[2] = data->tx_pn[3]; 368 seq[3] = data->tx_pn[2]; 369 seq[4] = data->tx_pn[1]; 370 seq[5] = data->tx_pn[0]; 371 } 372 373 return CCMP_TK_LEN; 374 } 375 376 377 static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv) 378 { 379 struct rtllib_ccmp_data *ccmp = priv; 380 381 seq_printf(m, 382 "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n", 383 ccmp->key_idx, ccmp->key_set, 384 ccmp->tx_pn, ccmp->rx_pn, 385 ccmp->dot11RSNAStatsCCMPFormatErrors, 386 ccmp->dot11RSNAStatsCCMPReplays, 387 ccmp->dot11RSNAStatsCCMPDecryptErrors); 388 } 389 390 static struct lib80211_crypto_ops rtllib_crypt_ccmp = { 391 .name = "R-CCMP", 392 .init = rtllib_ccmp_init, 393 .deinit = rtllib_ccmp_deinit, 394 .encrypt_mpdu = rtllib_ccmp_encrypt, 395 .decrypt_mpdu = rtllib_ccmp_decrypt, 396 .encrypt_msdu = NULL, 397 .decrypt_msdu = NULL, 398 .set_key = rtllib_ccmp_set_key, 399 .get_key = rtllib_ccmp_get_key, 400 .print_stats = rtllib_ccmp_print_stats, 401 .extra_mpdu_prefix_len = CCMP_HDR_LEN, 402 .extra_mpdu_postfix_len = CCMP_MIC_LEN, 403 .owner = THIS_MODULE, 404 }; 405 406 407 static int __init rtllib_crypto_ccmp_init(void) 408 { 409 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp); 410 } 411 412 413 static void __exit rtllib_crypto_ccmp_exit(void) 414 { 415 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp); 416 } 417 418 module_init(rtllib_crypto_ccmp_init); 419 module_exit(rtllib_crypto_ccmp_exit); 420 421 MODULE_LICENSE("GPL"); 422