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 30struct 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 dot11rsna_stats_ccmp_format_errors; 38 u32 dot11rsna_stats_ccmp_replays; 39 u32 dot11rsna_stats_ccmp_decrypt_errors; 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 50static 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) 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 67fail: 68 if (priv) { 69 if (priv->tfm) 70 crypto_free_aead(priv->tfm); 71 kfree(priv); 72 } 73 74 return NULL; 75} 76 77static void rtllib_ccmp_deinit(void *priv) 78{ 79 struct rtllib_ccmp_data *_priv = priv; 80 81 if (_priv && _priv->tfm) 82 crypto_free_aead(_priv->tfm); 83 kfree(priv); 84} 85 86static int ccmp_init_iv_and_aad(struct ieee80211_hdr *hdr, 87 u8 *pn, u8 *iv, u8 *aad) 88{ 89 u8 *pos, qc = 0; 90 size_t aad_len; 91 u16 fc; 92 int a4_included, qc_included; 93 94 fc = le16_to_cpu(hdr->frame_control); 95 a4_included = ieee80211_has_a4(hdr->frame_control); 96 97 qc_included = ((WLAN_FC_GET_TYPE(fc) == RTLLIB_FTYPE_DATA) && 98 (WLAN_FC_GET_STYPE(fc) & 0x80)); 99 aad_len = 22; 100 if (a4_included) 101 aad_len += 6; 102 if (qc_included) { 103 pos = (u8 *)&hdr->addr4; 104 if (a4_included) 105 pos += 6; 106 qc = *pos & 0x0f; 107 aad_len += 2; 108 } 109 /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC 110 * mode authentication are not allowed to collide, yet both are derived 111 * from the same vector. We only set L := 1 here to indicate that the 112 * data size can be represented in (L+1) bytes. The CCM layer will take 113 * care of storing the data length in the top (L+1) bytes and setting 114 * and clearing the other bits as is required to derive the two IVs. 115 */ 116 iv[0] = 0x1; 117 118 /* Nonce: QC | A2 | PN */ 119 iv[1] = qc; 120 memcpy(iv + 2, hdr->addr2, ETH_ALEN); 121 memcpy(iv + 8, pn, CCMP_PN_LEN); 122 123 /* AAD: 124 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one 125 * A1 | A2 | A3 126 * SC with bits 4..15 (seq#) masked to zero 127 * A4 (if present) 128 * QC (if present) 129 */ 130 pos = (u8 *)hdr; 131 aad[0] = pos[0] & 0x8f; 132 aad[1] = pos[1] & 0xc7; 133 memcpy(&aad[2], &hdr->addr1, ETH_ALEN); 134 memcpy(&aad[8], &hdr->addr2, ETH_ALEN); 135 memcpy(&aad[14], &hdr->addr3, ETH_ALEN); 136 pos = (u8 *)&hdr->seq_ctrl; 137 aad[20] = pos[0] & 0x0f; 138 aad[21] = 0; /* all bits masked */ 139 memset(aad + 22, 0, 8); 140 if (a4_included) 141 memcpy(aad + 22, hdr->addr4, ETH_ALEN); 142 if (qc_included) { 143 aad[a4_included ? 28 : 22] = qc; 144 /* rest of QC masked */ 145 } 146 147 return aad_len; 148} 149 150static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv) 151{ 152 struct rtllib_ccmp_data *key = priv; 153 int i; 154 u8 *pos; 155 struct ieee80211_hdr *hdr; 156 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 157 MAX_DEV_ADDR_SIZE); 158 if (skb_headroom(skb) < CCMP_HDR_LEN || 159 skb_tailroom(skb) < CCMP_MIC_LEN || 160 skb->len < hdr_len) 161 return -1; 162 163 pos = skb_push(skb, CCMP_HDR_LEN); 164 memmove(pos, pos + CCMP_HDR_LEN, hdr_len); 165 pos += hdr_len; 166 167 i = CCMP_PN_LEN - 1; 168 while (i >= 0) { 169 key->tx_pn[i]++; 170 if (key->tx_pn[i] != 0) 171 break; 172 i--; 173 } 174 175 *pos++ = key->tx_pn[5]; 176 *pos++ = key->tx_pn[4]; 177 *pos++ = 0; 178 *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */; 179 *pos++ = key->tx_pn[3]; 180 *pos++ = key->tx_pn[2]; 181 *pos++ = key->tx_pn[1]; 182 *pos++ = key->tx_pn[0]; 183 184 hdr = (struct ieee80211_hdr *)skb->data; 185 if (!tcb_desc->bHwSec) { 186 struct aead_request *req; 187 struct scatterlist sg[2]; 188 u8 *aad = key->tx_aad; 189 u8 iv[AES_BLOCK_LEN]; 190 int aad_len, ret; 191 int data_len = skb->len - hdr_len - CCMP_HDR_LEN; 192 193 req = aead_request_alloc(key->tfm, GFP_ATOMIC); 194 if (!req) 195 return -ENOMEM; 196 197 aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad); 198 199 skb_put(skb, CCMP_MIC_LEN); 200 sg_init_table(sg, 2); 201 sg_set_buf(&sg[0], aad, aad_len); 202 sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN, 203 data_len + CCMP_MIC_LEN); 204 205 aead_request_set_callback(req, 0, NULL, NULL); 206 aead_request_set_ad(req, aad_len); 207 aead_request_set_crypt(req, sg, sg, data_len, iv); 208 209 ret = crypto_aead_encrypt(req); 210 aead_request_free(req); 211 212 return ret; 213 } 214 215 return 0; 216} 217 218static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) 219{ 220 struct rtllib_ccmp_data *key = priv; 221 u8 keyidx, *pos; 222 struct ieee80211_hdr *hdr; 223 struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + 224 MAX_DEV_ADDR_SIZE); 225 u8 pn[6]; 226 227 if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { 228 key->dot11rsna_stats_ccmp_format_errors++; 229 return -1; 230 } 231 232 hdr = (struct ieee80211_hdr *)skb->data; 233 pos = skb->data + hdr_len; 234 keyidx = pos[3]; 235 if (!(keyidx & (1 << 5))) { 236 if (net_ratelimit()) { 237 pr_debug("CCMP: received packet without ExtIV flag from %pM\n", 238 hdr->addr2); 239 } 240 key->dot11rsna_stats_ccmp_format_errors++; 241 return -2; 242 } 243 keyidx >>= 6; 244 if (key->key_idx != keyidx) { 245 pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n", 246 key->key_idx, keyidx, priv); 247 return -6; 248 } 249 if (!key->key_set) { 250 if (net_ratelimit()) { 251 pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n", 252 hdr->addr2, keyidx); 253 } 254 return -3; 255 } 256 257 pn[0] = pos[7]; 258 pn[1] = pos[6]; 259 pn[2] = pos[5]; 260 pn[3] = pos[4]; 261 pn[4] = pos[1]; 262 pn[5] = pos[0]; 263 pos += 8; 264 if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) { 265 key->dot11rsna_stats_ccmp_replays++; 266 return -4; 267 } 268 if (!tcb_desc->bHwSec) { 269 size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN; 270 struct aead_request *req; 271 struct scatterlist sg[2]; 272 u8 *aad = key->rx_aad; 273 u8 iv[AES_BLOCK_LEN]; 274 int aad_len, ret; 275 276 req = aead_request_alloc(key->tfm, GFP_ATOMIC); 277 if (!req) 278 return -ENOMEM; 279 280 aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad); 281 282 sg_init_table(sg, 2); 283 sg_set_buf(&sg[0], aad, aad_len); 284 sg_set_buf(&sg[1], pos, data_len); 285 286 aead_request_set_callback(req, 0, NULL, NULL); 287 aead_request_set_ad(req, aad_len); 288 aead_request_set_crypt(req, sg, sg, data_len, iv); 289 290 ret = crypto_aead_decrypt(req); 291 aead_request_free(req); 292 293 if (ret) { 294 if (net_ratelimit()) { 295 pr_debug("CCMP: decrypt failed: STA= %pM\n", 296 hdr->addr2); 297 } 298 key->dot11rsna_stats_ccmp_decrypt_errors++; 299 return -5; 300 } 301 302 memcpy(key->rx_pn, pn, CCMP_PN_LEN); 303 } 304 /* Remove hdr and MIC */ 305 memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); 306 skb_pull(skb, CCMP_HDR_LEN); 307 skb_trim(skb, skb->len - CCMP_MIC_LEN); 308 309 return keyidx; 310} 311 312static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv) 313{ 314 struct rtllib_ccmp_data *data = priv; 315 int keyidx; 316 struct crypto_aead *tfm = data->tfm; 317 318 keyidx = data->key_idx; 319 memset(data, 0, sizeof(*data)); 320 data->key_idx = keyidx; 321 data->tfm = tfm; 322 if (len == CCMP_TK_LEN) { 323 memcpy(data->key, key, CCMP_TK_LEN); 324 data->key_set = 1; 325 if (seq) { 326 data->rx_pn[0] = seq[5]; 327 data->rx_pn[1] = seq[4]; 328 data->rx_pn[2] = seq[3]; 329 data->rx_pn[3] = seq[2]; 330 data->rx_pn[4] = seq[1]; 331 data->rx_pn[5] = seq[0]; 332 } 333 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) || 334 crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN)) 335 return -1; 336 } else if (len == 0) { 337 data->key_set = 0; 338 } else { 339 return -1; 340 } 341 342 return 0; 343} 344 345static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv) 346{ 347 struct rtllib_ccmp_data *data = priv; 348 349 if (len < CCMP_TK_LEN) 350 return -1; 351 352 if (!data->key_set) 353 return 0; 354 memcpy(key, data->key, CCMP_TK_LEN); 355 356 if (seq) { 357 seq[0] = data->tx_pn[5]; 358 seq[1] = data->tx_pn[4]; 359 seq[2] = data->tx_pn[3]; 360 seq[3] = data->tx_pn[2]; 361 seq[4] = data->tx_pn[1]; 362 seq[5] = data->tx_pn[0]; 363 } 364 365 return CCMP_TK_LEN; 366} 367 368static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv) 369{ 370 struct rtllib_ccmp_data *ccmp = priv; 371 372 seq_printf(m, 373 "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n", 374 ccmp->key_idx, ccmp->key_set, 375 ccmp->tx_pn, ccmp->rx_pn, 376 ccmp->dot11rsna_stats_ccmp_format_errors, 377 ccmp->dot11rsna_stats_ccmp_replays, 378 ccmp->dot11rsna_stats_ccmp_decrypt_errors); 379} 380 381static struct lib80211_crypto_ops rtllib_crypt_ccmp = { 382 .name = "R-CCMP", 383 .init = rtllib_ccmp_init, 384 .deinit = rtllib_ccmp_deinit, 385 .encrypt_mpdu = rtllib_ccmp_encrypt, 386 .decrypt_mpdu = rtllib_ccmp_decrypt, 387 .encrypt_msdu = NULL, 388 .decrypt_msdu = NULL, 389 .set_key = rtllib_ccmp_set_key, 390 .get_key = rtllib_ccmp_get_key, 391 .print_stats = rtllib_ccmp_print_stats, 392 .extra_mpdu_prefix_len = CCMP_HDR_LEN, 393 .extra_mpdu_postfix_len = CCMP_MIC_LEN, 394 .owner = THIS_MODULE, 395}; 396 397static int __init rtllib_crypto_ccmp_init(void) 398{ 399 return lib80211_register_crypto_ops(&rtllib_crypt_ccmp); 400} 401 402static void __exit rtllib_crypto_ccmp_exit(void) 403{ 404 lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp); 405} 406 407module_init(rtllib_crypto_ccmp_init); 408module_exit(rtllib_crypto_ccmp_exit); 409 410MODULE_LICENSE("GPL"); 411