drivers/net/wireless/intel/ipw2x00/libipw_crypto_ccmp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * libipw crypt: host-based CCMP encryption implementation for libipw
   4  *
   5  * Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi>
   6  * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/err.h>
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/slab.h>
  14 #include <linux/random.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/if_ether.h>
  18 #include <linux/if_arp.h>
  19 #include <asm/string.h>
  20 #include <linux/wireless.h>
  21 #include <linux/ieee80211.h>
  22 #include <linux/crypto.h>
  23 #include <crypto/aead.h>
  24 #include "libipw.h"
  25
  26 #define AES_BLOCK_LEN 16
  27 #define CCMP_HDR_LEN 8
  28 #define CCMP_MIC_LEN 8
  29 #define CCMP_TK_LEN 16
  30 #define CCMP_PN_LEN 6
  31
  32 struct libipw_ccmp_data {
  33         u8 key[CCMP_TK_LEN];
  34         int key_set;
  35
  36         u8 tx_pn[CCMP_PN_LEN];
  37         u8 rx_pn[CCMP_PN_LEN];
  38
  39         u32 dot11RSNAStatsCCMPFormatErrors;
  40         u32 dot11RSNAStatsCCMPReplays;
  41         u32 dot11RSNAStatsCCMPDecryptErrors;
  42
  43         int key_idx;
  44
  45         struct crypto_aead *tfm;
  46
  47         /* scratch buffers for virt_to_page() (crypto API) */
  48         u8 tx_aad[2 * AES_BLOCK_LEN];
  49         u8 rx_aad[2 * AES_BLOCK_LEN];
  50 };
  51
  52 static void *libipw_ccmp_init(int key_idx)
  53 {
  54         struct libipw_ccmp_data *priv;
  55
  56         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  57         if (priv == NULL)
  58                 goto fail;
  59         priv->key_idx = key_idx;
  60
  61         priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC);
  62         if (IS_ERR(priv->tfm)) {
  63                 priv->tfm = NULL;
  64                 goto fail;
  65         }
  66
  67         return priv;
  68
  69       fail:
  70         if (priv) {
  71                 if (priv->tfm)
  72                         crypto_free_aead(priv->tfm);
  73                 kfree(priv);
  74         }
  75
  76         return NULL;
  77 }
  78
  79 static void libipw_ccmp_deinit(void *priv)
  80 {
  81         struct libipw_ccmp_data *_priv = priv;
  82         if (_priv && _priv->tfm)
  83                 crypto_free_aead(_priv->tfm);
  84         kfree(priv);
  85 }
  86
  87 static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr,
  88                                 const u8 *pn, u8 *iv, u8 *aad)
  89 {
  90         u8 *pos, qc = 0;
  91         size_t aad_len;
  92         int a4_included, qc_included;
  93
  94         a4_included = ieee80211_has_a4(hdr->frame_control);
  95         qc_included = ieee80211_is_data_qos(hdr->frame_control);
  96
  97         aad_len = 22;
  98         if (a4_included)
  99                 aad_len += 6;
 100         if (qc_included) {
 101                 pos = (u8 *) & hdr->addr4;
 102                 if (a4_included)
 103                         pos += 6;
 104                 qc = *pos & 0x0f;
 105                 aad_len += 2;
 106         }
 107
 108         /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
 109          * mode authentication are not allowed to collide, yet both are derived
 110          * from the same vector. We only set L := 1 here to indicate that the
 111          * data size can be represented in (L+1) bytes. The CCM layer will take
 112          * care of storing the data length in the top (L+1) bytes and setting
 113          * and clearing the other bits as is required to derive the two IVs.
 114          */
 115         iv[0] = 0x1;
 116
 117         /* Nonce: QC | A2 | PN */
 118         iv[1] = qc;
 119         memcpy(iv + 2, hdr->addr2, ETH_ALEN);
 120         memcpy(iv + 8, pn, CCMP_PN_LEN);
 121
 122         /* AAD:
 123          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 124          * A1 | A2 | A3
 125          * SC with bits 4..15 (seq#) masked to zero
 126          * A4 (if present)
 127          * QC (if present)
 128          */
 129         pos = (u8 *) hdr;
 130         aad[0] = pos[0] & 0x8f;
 131         aad[1] = pos[1] & 0xc7;
 132         memcpy(aad + 2, &hdr->addrs, 3 * ETH_ALEN);
 133         pos = (u8 *) & hdr->seq_ctrl;
 134         aad[20] = pos[0] & 0x0f;
 135         aad[21] = 0;            /* all bits masked */
 136         memset(aad + 22, 0, 8);
 137         if (a4_included)
 138                 memcpy(aad + 22, hdr->addr4, ETH_ALEN);
 139         if (qc_included) {
 140                 aad[a4_included ? 28 : 22] = qc;
 141                 /* rest of QC masked */
 142         }
 143         return aad_len;
 144 }
 145
 146 static int libipw_ccmp_hdr(struct sk_buff *skb, int hdr_len,
 147                               u8 *aeskey, int keylen, void *priv)
 148 {
 149         struct libipw_ccmp_data *key = priv;
 150         int i;
 151         u8 *pos;
 152
 153         if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
 154                 return -1;
 155
 156         if (aeskey != NULL && keylen >= CCMP_TK_LEN)
 157                 memcpy(aeskey, key->key, CCMP_TK_LEN);
 158
 159         pos = skb_push(skb, CCMP_HDR_LEN);
 160         memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
 161         pos += hdr_len;
 162
 163         i = CCMP_PN_LEN - 1;
 164         while (i >= 0) {
 165                 key->tx_pn[i]++;
 166                 if (key->tx_pn[i] != 0)
 167                         break;
 168                 i--;
 169         }
 170
 171         *pos++ = key->tx_pn[5];
 172         *pos++ = key->tx_pn[4];
 173         *pos++ = 0;
 174         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
 175         *pos++ = key->tx_pn[3];
 176         *pos++ = key->tx_pn[2];
 177         *pos++ = key->tx_pn[1];
 178         *pos++ = key->tx_pn[0];
 179
 180         return CCMP_HDR_LEN;
 181 }
 182
 183 static int libipw_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 184 {
 185         struct libipw_ccmp_data *key = priv;
 186         struct ieee80211_hdr *hdr;
 187         struct aead_request *req;
 188         struct scatterlist sg[2];
 189         u8 *aad = key->tx_aad;
 190         u8 iv[AES_BLOCK_LEN];
 191         int len, data_len, aad_len;
 192         int ret;
 193
 194         if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
 195                 return -1;
 196
 197         data_len = skb->len - hdr_len;
 198         len = libipw_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
 199         if (len < 0)
 200                 return -1;
 201
 202         req = aead_request_alloc(key->tfm, GFP_ATOMIC);
 203         if (!req)
 204                 return -ENOMEM;
 205
 206         hdr = (struct ieee80211_hdr *)skb->data;
 207         aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
 208
 209         skb_put(skb, CCMP_MIC_LEN);
 210
 211         sg_init_table(sg, 2);
 212         sg_set_buf(&sg[0], aad, aad_len);
 213         sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
 214                    data_len + CCMP_MIC_LEN);
 215
 216         aead_request_set_callback(req, 0, NULL, NULL);
 217         aead_request_set_ad(req, aad_len);
 218         aead_request_set_crypt(req, sg, sg, data_len, iv);
 219
 220         ret = crypto_aead_encrypt(req);
 221         aead_request_free(req);
 222
 223         return ret;
 224 }
 225
 226 /*
 227  * deal with seq counter wrapping correctly.
 228  * refer to timer_after() for jiffies wrapping handling
 229  */
 230 static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
 231 {
 232         u32 iv32_n, iv16_n;
 233         u32 iv32_o, iv16_o;
 234
 235         iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
 236         iv16_n = (pn_n[4] << 8) | pn_n[5];
 237
 238         iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
 239         iv16_o = (pn_o[4] << 8) | pn_o[5];
 240
 241         if ((s32)iv32_n - (s32)iv32_o < 0 ||
 242             (iv32_n == iv32_o && iv16_n <= iv16_o))
 243                 return 1;
 244         return 0;
 245 }
 246
 247 static int libipw_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 248 {
 249         struct libipw_ccmp_data *key = priv;
 250         u8 keyidx, *pos;
 251         struct ieee80211_hdr *hdr;
 252         struct aead_request *req;
 253         struct scatterlist sg[2];
 254         u8 *aad = key->rx_aad;
 255         u8 iv[AES_BLOCK_LEN];
 256         u8 pn[6];
 257         int aad_len, ret;
 258         size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
 259
 260         if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
 261                 key->dot11RSNAStatsCCMPFormatErrors++;
 262                 return -1;
 263         }
 264
 265         hdr = (struct ieee80211_hdr *)skb->data;
 266         pos = skb->data + hdr_len;
 267         keyidx = pos[3];
 268         if (!(keyidx & (1 << 5))) {
 269                 net_dbg_ratelimited("CCMP: received packet without ExtIV flag from %pM\n",
 270                                     hdr->addr2);
 271                 key->dot11RSNAStatsCCMPFormatErrors++;
 272                 return -2;
 273         }
 274         keyidx >>= 6;
 275         if (key->key_idx != keyidx) {
 276                 net_dbg_ratelimited("CCMP: RX tkey->key_idx=%d frame keyidx=%d\n",
 277                                     key->key_idx, keyidx);
 278                 return -6;
 279         }
 280         if (!key->key_set) {
 281                 net_dbg_ratelimited("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
 282                                     hdr->addr2, keyidx);
 283                 return -3;
 284         }
 285
 286         pn[0] = pos[7];
 287         pn[1] = pos[6];
 288         pn[2] = pos[5];
 289         pn[3] = pos[4];
 290         pn[4] = pos[1];
 291         pn[5] = pos[0];
 292         pos += 8;
 293
 294         if (ccmp_replay_check(pn, key->rx_pn)) {
 295 #ifdef CONFIG_LIBIPW_DEBUG
 296                 net_dbg_ratelimited("CCMP: replay detected: STA=%pM previous PN %02x%02x%02x%02x%02x%02x received PN %02x%02x%02x%02x%02x%02x\n",
 297                                     hdr->addr2,
 298                                     key->rx_pn[0], key->rx_pn[1], key->rx_pn[2],
 299                                     key->rx_pn[3], key->rx_pn[4], key->rx_pn[5],
 300                                     pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]);
 301 #endif
 302                 key->dot11RSNAStatsCCMPReplays++;
 303                 return -4;
 304         }
 305
 306         req = aead_request_alloc(key->tfm, GFP_ATOMIC);
 307         if (!req)
 308                 return -ENOMEM;
 309
 310         aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
 311
 312         sg_init_table(sg, 2);
 313         sg_set_buf(&sg[0], aad, aad_len);
 314         sg_set_buf(&sg[1], pos, data_len);
 315
 316         aead_request_set_callback(req, 0, NULL, NULL);
 317         aead_request_set_ad(req, aad_len);
 318         aead_request_set_crypt(req, sg, sg, data_len, iv);
 319
 320         ret = crypto_aead_decrypt(req);
 321         aead_request_free(req);
 322
 323         if (ret) {
 324                 net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM (%d)\n",
 325                                     hdr->addr2, ret);
 326                 key->dot11RSNAStatsCCMPDecryptErrors++;
 327                 return -5;
 328         }
 329
 330         memcpy(key->rx_pn, pn, CCMP_PN_LEN);
 331
 332         /* Remove hdr and MIC */
 333         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
 334         skb_pull(skb, CCMP_HDR_LEN);
 335         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 336
 337         return keyidx;
 338 }
 339
 340 static int libipw_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
 341 {
 342         struct libipw_ccmp_data *data = priv;
 343         int keyidx;
 344         struct crypto_aead *tfm = data->tfm;
 345
 346         keyidx = data->key_idx;
 347         memset(data, 0, sizeof(*data));
 348         data->key_idx = keyidx;
 349         data->tfm = tfm;
 350         if (len == CCMP_TK_LEN) {
 351                 memcpy(data->key, key, CCMP_TK_LEN);
 352                 data->key_set = 1;
 353                 if (seq) {
 354                         data->rx_pn[0] = seq[5];
 355                         data->rx_pn[1] = seq[4];
 356                         data->rx_pn[2] = seq[3];
 357                         data->rx_pn[3] = seq[2];
 358                         data->rx_pn[4] = seq[1];
 359                         data->rx_pn[5] = seq[0];
 360                 }
 361                 if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
 362                     crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
 363                         return -1;
 364         } else if (len == 0)
 365                 data->key_set = 0;
 366         else
 367                 return -1;
 368
 369         return 0;
 370 }
 371
 372 static int libipw_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
 373 {
 374         struct libipw_ccmp_data *data = priv;
 375
 376         if (len < CCMP_TK_LEN)
 377                 return -1;
 378
 379         if (!data->key_set)
 380                 return 0;
 381         memcpy(key, data->key, CCMP_TK_LEN);
 382
 383         if (seq) {
 384                 seq[0] = data->tx_pn[5];
 385                 seq[1] = data->tx_pn[4];
 386                 seq[2] = data->tx_pn[3];
 387                 seq[3] = data->tx_pn[2];
 388                 seq[4] = data->tx_pn[1];
 389                 seq[5] = data->tx_pn[0];
 390         }
 391
 392         return CCMP_TK_LEN;
 393 }
 394
 395 static void libipw_ccmp_print_stats(struct seq_file *m, void *priv)
 396 {
 397         struct libipw_ccmp_data *ccmp = priv;
 398
 399         seq_printf(m,
 400                    "key[%d] alg=CCMP key_set=%d "
 401                    "tx_pn=%02x%02x%02x%02x%02x%02x "
 402                    "rx_pn=%02x%02x%02x%02x%02x%02x "
 403                    "format_errors=%d replays=%d decrypt_errors=%d\n",
 404                    ccmp->key_idx, ccmp->key_set,
 405                    ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2],
 406                    ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5],
 407                    ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2],
 408                    ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5],
 409                    ccmp->dot11RSNAStatsCCMPFormatErrors,
 410                    ccmp->dot11RSNAStatsCCMPReplays,
 411                    ccmp->dot11RSNAStatsCCMPDecryptErrors);
 412 }
 413
 414 static const struct libipw_crypto_ops libipw_crypt_ccmp = {
 415         .name = "CCMP",
 416         .init = libipw_ccmp_init,
 417         .deinit = libipw_ccmp_deinit,
 418         .encrypt_mpdu = libipw_ccmp_encrypt,
 419         .decrypt_mpdu = libipw_ccmp_decrypt,
 420         .encrypt_msdu = NULL,
 421         .decrypt_msdu = NULL,
 422         .set_key = libipw_ccmp_set_key,
 423         .get_key = libipw_ccmp_get_key,
 424         .print_stats = libipw_ccmp_print_stats,
 425         .extra_mpdu_prefix_len = CCMP_HDR_LEN,
 426         .extra_mpdu_postfix_len = CCMP_MIC_LEN,
 427         .owner = THIS_MODULE,
 428 };
 429
 430 int __init libipw_crypto_ccmp_init(void)
 431 {
 432         return libipw_register_crypto_ops(&libipw_crypt_ccmp);
 433 }
 434
 435 void libipw_crypto_ccmp_exit(void)
 436 {
 437         libipw_unregister_crypto_ops(&libipw_crypt_ccmp);
 438 }