linux/drivers/staging/rtl8192e/rtllib_crypt_ccmp.c
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   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 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
  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 == 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
  67fail:
  68        if (priv) {
  69                if (priv->tfm)
  70                        crypto_free_aead(priv->tfm);
  71                kfree(priv);
  72        }
  73
  74        return NULL;
  75}
  76
  77
  78static 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
  88static 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, 3 * ETH_ALEN);
 137        pos = (u8 *) &hdr->seq_ctl;
 138        aad[20] = pos[0] & 0x0f;
 139        aad[21] = 0; /* all bits masked */
 140        memset(aad + 22, 0, 8);
 141        if (a4_included)
 142                memcpy(aad + 22, hdr->addr4, ETH_ALEN);
 143        if (qc_included) {
 144                aad[a4_included ? 28 : 22] = qc;
 145                /* rest of QC masked */
 146        }
 147
 148        return aad_len;
 149}
 150
 151
 152
 153static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 154{
 155        struct rtllib_ccmp_data *key = priv;
 156        int i;
 157        u8 *pos;
 158        struct rtllib_hdr_4addr *hdr;
 159        struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 160                                    MAX_DEV_ADDR_SIZE);
 161        if (skb_headroom(skb) < CCMP_HDR_LEN ||
 162            skb_tailroom(skb) < CCMP_MIC_LEN ||
 163            skb->len < hdr_len)
 164                return -1;
 165
 166        pos = skb_push(skb, CCMP_HDR_LEN);
 167        memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
 168        pos += hdr_len;
 169
 170        i = CCMP_PN_LEN - 1;
 171        while (i >= 0) {
 172                key->tx_pn[i]++;
 173                if (key->tx_pn[i] != 0)
 174                        break;
 175                i--;
 176        }
 177
 178        *pos++ = key->tx_pn[5];
 179        *pos++ = key->tx_pn[4];
 180        *pos++ = 0;
 181        *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
 182        *pos++ = key->tx_pn[3];
 183        *pos++ = key->tx_pn[2];
 184        *pos++ = key->tx_pn[1];
 185        *pos++ = key->tx_pn[0];
 186
 187        hdr = (struct rtllib_hdr_4addr *) skb->data;
 188        if (!tcb_desc->bHwSec) {
 189                struct aead_request *req;
 190                struct scatterlist sg[2];
 191                u8 *aad = key->tx_aad;
 192                u8 iv[AES_BLOCK_LEN];
 193                int aad_len, ret;
 194                int data_len = skb->len - hdr_len - CCMP_HDR_LEN;
 195
 196                req = aead_request_alloc(key->tfm, GFP_ATOMIC);
 197                if (!req)
 198                        return -ENOMEM;
 199
 200                aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
 201
 202                skb_put(skb, CCMP_MIC_LEN);
 203                sg_init_table(sg, 2);
 204                sg_set_buf(&sg[0], aad, aad_len);
 205                sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
 206                           data_len + CCMP_MIC_LEN);
 207
 208                aead_request_set_callback(req, 0, NULL, NULL);
 209                aead_request_set_ad(req, aad_len);
 210                aead_request_set_crypt(req, sg, sg, data_len, iv);
 211
 212                ret = crypto_aead_encrypt(req);
 213                aead_request_free(req);
 214
 215                return ret;
 216        }
 217
 218        return 0;
 219}
 220
 221
 222static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 223{
 224        struct rtllib_ccmp_data *key = priv;
 225        u8 keyidx, *pos;
 226        struct rtllib_hdr_4addr *hdr;
 227        struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb +
 228                                    MAX_DEV_ADDR_SIZE);
 229        u8 pn[6];
 230
 231        if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
 232                key->dot11RSNAStatsCCMPFormatErrors++;
 233                return -1;
 234        }
 235
 236        hdr = (struct rtllib_hdr_4addr *) skb->data;
 237        pos = skb->data + hdr_len;
 238        keyidx = pos[3];
 239        if (!(keyidx & (1 << 5))) {
 240                if (net_ratelimit()) {
 241                        pr_debug("CCMP: received packet without ExtIV flag from %pM\n",
 242                                 hdr->addr2);
 243                }
 244                key->dot11RSNAStatsCCMPFormatErrors++;
 245                return -2;
 246        }
 247        keyidx >>= 6;
 248        if (key->key_idx != keyidx) {
 249                pr_debug("CCMP: RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
 250                         key->key_idx, keyidx, priv);
 251                return -6;
 252        }
 253        if (!key->key_set) {
 254                if (net_ratelimit()) {
 255                        pr_debug("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
 256                                 hdr->addr2, keyidx);
 257                }
 258                return -3;
 259        }
 260
 261        pn[0] = pos[7];
 262        pn[1] = pos[6];
 263        pn[2] = pos[5];
 264        pn[3] = pos[4];
 265        pn[4] = pos[1];
 266        pn[5] = pos[0];
 267        pos += 8;
 268        if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
 269                key->dot11RSNAStatsCCMPReplays++;
 270                return -4;
 271        }
 272        if (!tcb_desc->bHwSec) {
 273                size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
 274                struct aead_request *req;
 275                struct scatterlist sg[2];
 276                u8 *aad = key->rx_aad;
 277                u8 iv[AES_BLOCK_LEN];
 278                int aad_len, ret;
 279
 280                req = aead_request_alloc(key->tfm, GFP_ATOMIC);
 281                if(!req)
 282                        return -ENOMEM;
 283
 284                aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
 285
 286                sg_init_table(sg, 2);
 287                sg_set_buf(&sg[0], aad, aad_len);
 288                sg_set_buf(&sg[1], pos, data_len);
 289
 290                aead_request_set_callback(req, 0, NULL, NULL);
 291                aead_request_set_ad(req, aad_len);
 292                aead_request_set_crypt(req, sg, sg, data_len, iv);
 293
 294                ret = crypto_aead_decrypt(req);
 295                aead_request_free(req);
 296
 297                if (ret) {
 298                        if (net_ratelimit()) {
 299                                pr_debug("CCMP: decrypt failed: STA= %pM\n",
 300                                         hdr->addr2);
 301                        }
 302                        key->dot11RSNAStatsCCMPDecryptErrors++;
 303                        return -5;
 304                }
 305
 306                memcpy(key->rx_pn, pn, CCMP_PN_LEN);
 307        }
 308        /* Remove hdr and MIC */
 309        memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
 310        skb_pull(skb, CCMP_HDR_LEN);
 311        skb_trim(skb, skb->len - CCMP_MIC_LEN);
 312
 313        return keyidx;
 314}
 315
 316
 317static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
 318{
 319        struct rtllib_ccmp_data *data = priv;
 320        int keyidx;
 321        struct crypto_aead *tfm = data->tfm;
 322
 323        keyidx = data->key_idx;
 324        memset(data, 0, sizeof(*data));
 325        data->key_idx = keyidx;
 326        data->tfm = tfm;
 327        if (len == CCMP_TK_LEN) {
 328                memcpy(data->key, key, CCMP_TK_LEN);
 329                data->key_set = 1;
 330                if (seq) {
 331                        data->rx_pn[0] = seq[5];
 332                        data->rx_pn[1] = seq[4];
 333                        data->rx_pn[2] = seq[3];
 334                        data->rx_pn[3] = seq[2];
 335                        data->rx_pn[4] = seq[1];
 336                        data->rx_pn[5] = seq[0];
 337                }
 338                if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
 339                        crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
 340                                return -1;
 341        } else if (len == 0) {
 342                data->key_set = 0;
 343        } else {
 344                return -1;
 345        }
 346
 347        return 0;
 348}
 349
 350
 351static int rtllib_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
 352{
 353        struct rtllib_ccmp_data *data = priv;
 354
 355        if (len < CCMP_TK_LEN)
 356                return -1;
 357
 358        if (!data->key_set)
 359                return 0;
 360        memcpy(key, data->key, CCMP_TK_LEN);
 361
 362        if (seq) {
 363                seq[0] = data->tx_pn[5];
 364                seq[1] = data->tx_pn[4];
 365                seq[2] = data->tx_pn[3];
 366                seq[3] = data->tx_pn[2];
 367                seq[4] = data->tx_pn[1];
 368                seq[5] = data->tx_pn[0];
 369        }
 370
 371        return CCMP_TK_LEN;
 372}
 373
 374
 375static void rtllib_ccmp_print_stats(struct seq_file *m, void *priv)
 376{
 377        struct rtllib_ccmp_data *ccmp = priv;
 378
 379        seq_printf(m,
 380                   "key[%d] alg=CCMP key_set=%d tx_pn=%pM rx_pn=%pM format_errors=%d replays=%d decrypt_errors=%d\n",
 381                   ccmp->key_idx, ccmp->key_set,
 382                   ccmp->tx_pn, ccmp->rx_pn,
 383                   ccmp->dot11RSNAStatsCCMPFormatErrors,
 384                   ccmp->dot11RSNAStatsCCMPReplays,
 385                   ccmp->dot11RSNAStatsCCMPDecryptErrors);
 386}
 387
 388static struct lib80211_crypto_ops rtllib_crypt_ccmp = {
 389        .name                   = "R-CCMP",
 390        .init                   = rtllib_ccmp_init,
 391        .deinit                 = rtllib_ccmp_deinit,
 392        .encrypt_mpdu           = rtllib_ccmp_encrypt,
 393        .decrypt_mpdu           = rtllib_ccmp_decrypt,
 394        .encrypt_msdu           = NULL,
 395        .decrypt_msdu           = NULL,
 396        .set_key                = rtllib_ccmp_set_key,
 397        .get_key                = rtllib_ccmp_get_key,
 398        .print_stats            = rtllib_ccmp_print_stats,
 399        .extra_mpdu_prefix_len = CCMP_HDR_LEN,
 400        .extra_mpdu_postfix_len = CCMP_MIC_LEN,
 401        .owner                  = THIS_MODULE,
 402};
 403
 404
 405static int __init rtllib_crypto_ccmp_init(void)
 406{
 407        return lib80211_register_crypto_ops(&rtllib_crypt_ccmp);
 408}
 409
 410
 411static void __exit rtllib_crypto_ccmp_exit(void)
 412{
 413        lib80211_unregister_crypto_ops(&rtllib_crypt_ccmp);
 414}
 415
 416module_init(rtllib_crypto_ccmp_init);
 417module_exit(rtllib_crypto_ccmp_exit);
 418
 419MODULE_LICENSE("GPL");
 420