The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_crypto_ccmp.c

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    1 /*-
    2  * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. The name of the author may not be used to endorse or promote products
   14  *    derived from this software without specific prior written permission.
   15  *
   16  * Alternatively, this software may be distributed under the terms of the
   17  * GNU General Public License ("GPL") version 2 as published by the Free
   18  * Software Foundation.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD$");
   34 
   35 /*
   36  * IEEE 802.11i AES-CCMP crypto support.
   37  *
   38  * Part of this module is derived from similar code in the Host
   39  * AP driver. The code is used with the consent of the author and
   40  * it's license is included below.
   41  */
   42 #include <sys/param.h>
   43 #include <sys/systm.h> 
   44 #include <sys/mbuf.h>   
   45 #include <sys/malloc.h>
   46 #include <sys/kernel.h>
   47 #include <sys/module.h>
   48 
   49 #include <sys/socket.h>
   50 
   51 #include <net/if.h>
   52 #include <net/if_media.h>
   53 #include <net/ethernet.h>
   54 
   55 #include <net80211/ieee80211_var.h>
   56 
   57 #include <crypto/rijndael/rijndael.h>
   58 
   59 #define AES_BLOCK_LEN 16
   60 
   61 struct ccmp_ctx {
   62         struct ieee80211com *cc_ic;     /* for diagnostics */
   63         rijndael_ctx         cc_aes;
   64 };
   65 
   66 static  void *ccmp_attach(struct ieee80211com *, struct ieee80211_key *);
   67 static  void ccmp_detach(struct ieee80211_key *);
   68 static  int ccmp_setkey(struct ieee80211_key *);
   69 static  int ccmp_encap(struct ieee80211_key *k, struct mbuf *, u_int8_t keyid);
   70 static  int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
   71 static  int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
   72 static  int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);
   73 
   74 static const struct ieee80211_cipher ccmp = {
   75         .ic_name        = "AES-CCM",
   76         .ic_cipher      = IEEE80211_CIPHER_AES_CCM,
   77         .ic_header      = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
   78                           IEEE80211_WEP_EXTIVLEN,
   79         .ic_trailer     = IEEE80211_WEP_MICLEN,
   80         .ic_miclen      = 0,
   81         .ic_attach      = ccmp_attach,
   82         .ic_detach      = ccmp_detach,
   83         .ic_setkey      = ccmp_setkey,
   84         .ic_encap       = ccmp_encap,
   85         .ic_decap       = ccmp_decap,
   86         .ic_enmic       = ccmp_enmic,
   87         .ic_demic       = ccmp_demic,
   88 };
   89 
   90 static  int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
   91 static  int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn,
   92                 struct mbuf *, int hdrlen);
   93 
   94 /* number of references from net80211 layer */
   95 static  int nrefs = 0;
   96 
   97 static void *
   98 ccmp_attach(struct ieee80211com *ic, struct ieee80211_key *k)
   99 {
  100         struct ccmp_ctx *ctx;
  101 
  102         MALLOC(ctx, struct ccmp_ctx *, sizeof(struct ccmp_ctx),
  103                 M_DEVBUF, M_NOWAIT | M_ZERO);
  104         if (ctx == NULL) {
  105                 ic->ic_stats.is_crypto_nomem++;
  106                 return NULL;
  107         }
  108         ctx->cc_ic = ic;
  109         nrefs++;                        /* NB: we assume caller locking */
  110         return ctx;
  111 }
  112 
  113 static void
  114 ccmp_detach(struct ieee80211_key *k)
  115 {
  116         struct ccmp_ctx *ctx = k->wk_private;
  117 
  118         FREE(ctx, M_DEVBUF);
  119         KASSERT(nrefs > 0, ("imbalanced attach/detach"));
  120         nrefs--;                        /* NB: we assume caller locking */
  121 }
  122 
  123 static int
  124 ccmp_setkey(struct ieee80211_key *k)
  125 {
  126         struct ccmp_ctx *ctx = k->wk_private;
  127 
  128         if (k->wk_keylen != (128/NBBY)) {
  129                 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
  130                         "%s: Invalid key length %u, expecting %u\n",
  131                         __func__, k->wk_keylen, 128/NBBY);
  132                 return 0;
  133         }
  134         if (k->wk_flags & IEEE80211_KEY_SWCRYPT)
  135                 rijndael_set_key(&ctx->cc_aes, k->wk_key, k->wk_keylen*NBBY);
  136         return 1;
  137 }
  138 
  139 /*
  140  * Add privacy headers appropriate for the specified key.
  141  */
  142 static int
  143 ccmp_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid)
  144 {
  145         struct ccmp_ctx *ctx = k->wk_private;
  146         struct ieee80211com *ic = ctx->cc_ic;
  147         u_int8_t *ivp;
  148         int hdrlen;
  149 
  150         hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
  151 
  152         /*
  153          * Copy down 802.11 header and add the IV, KeyID, and ExtIV.
  154          */
  155         M_PREPEND(m, ccmp.ic_header, M_NOWAIT);
  156         if (m == NULL)
  157                 return 0;
  158         ivp = mtod(m, u_int8_t *);
  159         ovbcopy(ivp + ccmp.ic_header, ivp, hdrlen);
  160         ivp += hdrlen;
  161 
  162         k->wk_keytsc++;         /* XXX wrap at 48 bits */
  163         ivp[0] = k->wk_keytsc >> 0;             /* PN0 */
  164         ivp[1] = k->wk_keytsc >> 8;             /* PN1 */
  165         ivp[2] = 0;                             /* Reserved */
  166         ivp[3] = keyid | IEEE80211_WEP_EXTIV;   /* KeyID | ExtID */
  167         ivp[4] = k->wk_keytsc >> 16;            /* PN2 */
  168         ivp[5] = k->wk_keytsc >> 24;            /* PN3 */
  169         ivp[6] = k->wk_keytsc >> 32;            /* PN4 */
  170         ivp[7] = k->wk_keytsc >> 40;            /* PN5 */
  171 
  172         /*
  173          * Finally, do software encrypt if neeed.
  174          */
  175         if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
  176             !ccmp_encrypt(k, m, hdrlen))
  177                 return 0;
  178 
  179         return 1;
  180 }
  181 
  182 /*
  183  * Add MIC to the frame as needed.
  184  */
  185 static int
  186 ccmp_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
  187 {
  188 
  189         return 1;
  190 }
  191 
  192 static __inline uint64_t
  193 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
  194 {
  195         uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
  196         uint16_t iv16 = (b4 << 0) | (b5 << 8);
  197         return (((uint64_t)iv16) << 32) | iv32;
  198 }
  199 
  200 /*
  201  * Validate and strip privacy headers (and trailer) for a
  202  * received frame. The specified key should be correct but
  203  * is also verified.
  204  */
  205 static int
  206 ccmp_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
  207 {
  208         struct ccmp_ctx *ctx = k->wk_private;
  209         struct ieee80211_frame *wh;
  210         uint8_t *ivp;
  211         uint64_t pn;
  212 
  213         /*
  214          * Header should have extended IV and sequence number;
  215          * verify the former and validate the latter.
  216          */
  217         wh = mtod(m, struct ieee80211_frame *);
  218         ivp = mtod(m, uint8_t *) + hdrlen;
  219         if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
  220                 /*
  221                  * No extended IV; discard frame.
  222                  */
  223                 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
  224                         "[%s] Missing ExtIV for AES-CCM cipher\n",
  225                         ether_sprintf(wh->i_addr2));
  226                 ctx->cc_ic->ic_stats.is_rx_ccmpformat++;
  227                 return 0;
  228         }
  229         pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
  230         if (pn <= k->wk_keyrsc) {
  231                 /*
  232                  * Replay violation.
  233                  */
  234                 ieee80211_notify_replay_failure(ctx->cc_ic, wh, k, pn);
  235                 ctx->cc_ic->ic_stats.is_rx_ccmpreplay++;
  236                 return 0;
  237         }
  238 
  239         /*
  240          * Check if the device handled the decrypt in hardware.
  241          * If so we just strip the header; otherwise we need to
  242          * handle the decrypt in software.  Note that for the
  243          * latter we leave the header in place for use in the
  244          * decryption work.
  245          */
  246         if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
  247             !ccmp_decrypt(k, pn, m, hdrlen))
  248                 return 0;
  249 
  250         /*
  251          * Copy up 802.11 header and strip crypto bits.
  252          */
  253         ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + ccmp.ic_header, hdrlen);
  254         m_adj(m, ccmp.ic_header);
  255         m_adj(m, -ccmp.ic_trailer);
  256 
  257         /*
  258          * Ok to update rsc now.
  259          */
  260         k->wk_keyrsc = pn;
  261 
  262         return 1;
  263 }
  264 
  265 /*
  266  * Verify and strip MIC from the frame.
  267  */
  268 static int
  269 ccmp_demic(struct ieee80211_key *k, struct mbuf *m, int force)
  270 {
  271         return 1;
  272 }
  273 
  274 static __inline void
  275 xor_block(uint8_t *b, const uint8_t *a, size_t len)
  276 {
  277         int i;
  278         for (i = 0; i < len; i++)
  279                 b[i] ^= a[i];
  280 }
  281 
  282 /*
  283  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
  284  *
  285  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
  286  *
  287  * This program is free software; you can redistribute it and/or modify
  288  * it under the terms of the GNU General Public License version 2 as
  289  * published by the Free Software Foundation. See README and COPYING for
  290  * more details.
  291  *
  292  * Alternatively, this software may be distributed under the terms of BSD
  293  * license.
  294  */
  295 
  296 static void
  297 ccmp_init_blocks(rijndael_ctx *ctx, struct ieee80211_frame *wh,
  298         u_int64_t pn, size_t dlen,
  299         uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN],
  300         uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN])
  301 {
  302 #define IS_4ADDRESS(wh) \
  303         ((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) == IEEE80211_FC1_DIR_DSTODS)
  304 #define IS_QOS_DATA(wh) IEEE80211_QOS_HAS_SEQ(wh)
  305 
  306         /* CCM Initial Block:
  307          * Flag (Include authentication header, M=3 (8-octet MIC),
  308          *       L=1 (2-octet Dlen))
  309          * Nonce: 0x00 | A2 | PN
  310          * Dlen */
  311         b0[0] = 0x59;
  312         /* NB: b0[1] set below */
  313         IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2);
  314         b0[8] = pn >> 40;
  315         b0[9] = pn >> 32;
  316         b0[10] = pn >> 24;
  317         b0[11] = pn >> 16;
  318         b0[12] = pn >> 8;
  319         b0[13] = pn >> 0;
  320         b0[14] = (dlen >> 8) & 0xff;
  321         b0[15] = dlen & 0xff;
  322 
  323         /* AAD:
  324          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
  325          * A1 | A2 | A3
  326          * SC with bits 4..15 (seq#) masked to zero
  327          * A4 (if present)
  328          * QC (if present)
  329          */
  330         aad[0] = 0;     /* AAD length >> 8 */
  331         /* NB: aad[1] set below */
  332         aad[2] = wh->i_fc[0] & 0x8f;    /* XXX magic #s */
  333         aad[3] = wh->i_fc[1] & 0xc7;    /* XXX magic #s */
  334         /* NB: we know 3 addresses are contiguous */
  335         memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
  336         aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
  337         aad[23] = 0; /* all bits masked */
  338         /*
  339          * Construct variable-length portion of AAD based
  340          * on whether this is a 4-address frame/QOS frame.
  341          * We always zero-pad to 32 bytes before running it
  342          * through the cipher.
  343          *
  344          * We also fill in the priority bits of the CCM
  345          * initial block as we know whether or not we have
  346          * a QOS frame.
  347          */
  348         if (IS_4ADDRESS(wh)) {
  349                 IEEE80211_ADDR_COPY(aad + 24,
  350                         ((struct ieee80211_frame_addr4 *)wh)->i_addr4);
  351                 if (IS_QOS_DATA(wh)) {
  352                         struct ieee80211_qosframe_addr4 *qwh4 =
  353                                 (struct ieee80211_qosframe_addr4 *) wh;
  354                         aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
  355                         aad[31] = 0;
  356                         b0[1] = aad[30];
  357                         aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
  358                 } else {
  359                         *(u_int16_t *)&aad[30] = 0;
  360                         b0[1] = 0;
  361                         aad[1] = 22 + IEEE80211_ADDR_LEN;
  362                 }
  363         } else {
  364                 if (IS_QOS_DATA(wh)) {
  365                         struct ieee80211_qosframe *qwh =
  366                                 (struct ieee80211_qosframe*) wh;
  367                         aad[24] = qwh->i_qos[0] & 0x0f; /* just priority bits */
  368                         aad[25] = 0;
  369                         b0[1] = aad[24];
  370                         aad[1] = 22 + 2;
  371                 } else {
  372                         *(u_int16_t *)&aad[24] = 0;
  373                         b0[1] = 0;
  374                         aad[1] = 22;
  375                 }
  376                 *(u_int16_t *)&aad[26] = 0;
  377                 *(u_int32_t *)&aad[28] = 0;
  378         }
  379 
  380         /* Start with the first block and AAD */
  381         rijndael_encrypt(ctx, b0, auth);
  382         xor_block(auth, aad, AES_BLOCK_LEN);
  383         rijndael_encrypt(ctx, auth, auth);
  384         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
  385         rijndael_encrypt(ctx, auth, auth);
  386         b0[0] &= 0x07;
  387         b0[14] = b0[15] = 0;
  388         rijndael_encrypt(ctx, b0, s0);
  389 #undef  IS_QOS_DATA
  390 #undef  IS_4ADDRESS
  391 }
  392 
  393 #define CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do {  \
  394         /* Authentication */                            \
  395         xor_block(_b, _pos, _len);                      \
  396         rijndael_encrypt(&ctx->cc_aes, _b, _b);         \
  397         /* Encryption, with counter */                  \
  398         _b0[14] = (_i >> 8) & 0xff;                     \
  399         _b0[15] = _i & 0xff;                            \
  400         rijndael_encrypt(&ctx->cc_aes, _b0, _e);        \
  401         xor_block(_pos, _e, _len);                      \
  402 } while (0)
  403 
  404 static int
  405 ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
  406 {
  407         struct ccmp_ctx *ctx = key->wk_private;
  408         struct ieee80211_frame *wh;
  409         struct mbuf *m = m0;
  410         int data_len, i, space;
  411         uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN],
  412                 e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN];
  413         uint8_t *pos;
  414 
  415         ctx->cc_ic->ic_stats.is_crypto_ccmp++;
  416 
  417         wh = mtod(m, struct ieee80211_frame *);
  418         data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header);
  419         ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc,
  420                 data_len, b0, aad, b, s0);
  421 
  422         i = 1;
  423         pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
  424         /* NB: assumes header is entirely in first mbuf */
  425         space = m->m_len - (hdrlen + ccmp.ic_header);
  426         for (;;) {
  427                 if (space > data_len)
  428                         space = data_len;
  429                 /*
  430                  * Do full blocks.
  431                  */
  432                 while (space >= AES_BLOCK_LEN) {
  433                         CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN);
  434                         pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
  435                         data_len -= AES_BLOCK_LEN;
  436                         i++;
  437                 }
  438                 if (data_len <= 0)              /* no more data */
  439                         break;
  440                 m = m->m_next;
  441                 if (m == NULL) {                /* last buffer */
  442                         if (space != 0) {
  443                                 /*
  444                                  * Short last block.
  445                                  */
  446                                 CCMP_ENCRYPT(i, b, b0, pos, e, space);
  447                         }
  448                         break;
  449                 }
  450                 if (space != 0) {
  451                         uint8_t *pos_next;
  452                         int space_next;
  453                         int len, dl, sp;
  454                         struct mbuf *n;
  455 
  456                         /*
  457                          * Block straddles one or more mbufs, gather data
  458                          * into the block buffer b, apply the cipher, then
  459                          * scatter the results back into the mbuf chain.
  460                          * The buffer will automatically get space bytes
  461                          * of data at offset 0 copied in+out by the
  462                          * CCMP_ENCRYPT request so we must take care of
  463                          * the remaining data.
  464                          */
  465                         n = m;
  466                         dl = data_len;
  467                         sp = space;
  468                         for (;;) {
  469                                 pos_next = mtod(n, uint8_t *);
  470                                 len = min(dl, AES_BLOCK_LEN);
  471                                 space_next = len > sp ? len - sp : 0;
  472                                 if (n->m_len >= space_next) {
  473                                         /*
  474                                          * This mbuf has enough data; just grab
  475                                          * what we need and stop.
  476                                          */
  477                                         xor_block(b+sp, pos_next, space_next);
  478                                         break;
  479                                 }
  480                                 /*
  481                                  * This mbuf's contents are insufficient,
  482                                  * take 'em all and prepare to advance to
  483                                  * the next mbuf.
  484                                  */
  485                                 xor_block(b+sp, pos_next, n->m_len);
  486                                 sp += n->m_len, dl -= n->m_len;
  487                                 n = n->m_next;
  488                                 if (n == NULL)
  489                                         break;
  490                         }
  491 
  492                         CCMP_ENCRYPT(i, b, b0, pos, e, space);
  493 
  494                         /* NB: just like above, but scatter data to mbufs */
  495                         dl = data_len;
  496                         sp = space;
  497                         for (;;) {
  498                                 pos_next = mtod(m, uint8_t *);
  499                                 len = min(dl, AES_BLOCK_LEN);
  500                                 space_next = len > sp ? len - sp : 0;
  501                                 if (m->m_len >= space_next) {
  502                                         xor_block(pos_next, e+sp, space_next);
  503                                         break;
  504                                 }
  505                                 xor_block(pos_next, e+sp, m->m_len);
  506                                 sp += m->m_len, dl -= m->m_len;
  507                                 m = m->m_next;
  508                                 if (m == NULL)
  509                                         goto done;
  510                         }
  511                         /*
  512                          * Do bookkeeping.  m now points to the last mbuf
  513                          * we grabbed data from.  We know we consumed a
  514                          * full block of data as otherwise we'd have hit
  515                          * the end of the mbuf chain, so deduct from data_len.
  516                          * Otherwise advance the block number (i) and setup
  517                          * pos+space to reflect contents of the new mbuf.
  518                          */
  519                         data_len -= AES_BLOCK_LEN;
  520                         i++;
  521                         pos = pos_next + space_next;
  522                         space = m->m_len - space_next;
  523                 } else {
  524                         /*
  525                          * Setup for next buffer.
  526                          */
  527                         pos = mtod(m, uint8_t *);
  528                         space = m->m_len;
  529                 }
  530         }
  531 done:
  532         /* tack on MIC */
  533         xor_block(b, s0, ccmp.ic_trailer);
  534         return m_append(m0, ccmp.ic_trailer, b);
  535 }
  536 #undef CCMP_ENCRYPT
  537 
  538 #define CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do {  \
  539         /* Decrypt, with counter */                     \
  540         _b0[14] = (_i >> 8) & 0xff;                     \
  541         _b0[15] = _i & 0xff;                            \
  542         rijndael_encrypt(&ctx->cc_aes, _b0, _b);        \
  543         xor_block(_pos, _b, _len);                      \
  544         /* Authentication */                            \
  545         xor_block(_a, _pos, _len);                      \
  546         rijndael_encrypt(&ctx->cc_aes, _a, _a);         \
  547 } while (0)
  548 
  549 static int
  550 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m, int hdrlen)
  551 {
  552         struct ccmp_ctx *ctx = key->wk_private;
  553         struct ieee80211_frame *wh;
  554         uint8_t aad[2 * AES_BLOCK_LEN];
  555         uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
  556         uint8_t mic[AES_BLOCK_LEN];
  557         size_t data_len;
  558         int i;
  559         uint8_t *pos;
  560         u_int space;
  561 
  562         ctx->cc_ic->ic_stats.is_crypto_ccmp++;
  563 
  564         wh = mtod(m, struct ieee80211_frame *);
  565         data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer);
  566         ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, b0, aad, a, b);
  567         m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic);
  568         xor_block(mic, b, ccmp.ic_trailer);
  569 
  570         i = 1;
  571         pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
  572         space = m->m_len - (hdrlen + ccmp.ic_header);
  573         for (;;) {
  574                 if (space > data_len)
  575                         space = data_len;
  576                 while (space >= AES_BLOCK_LEN) {
  577                         CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
  578                         pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
  579                         data_len -= AES_BLOCK_LEN;
  580                         i++;
  581                 }
  582                 if (data_len <= 0)              /* no more data */
  583                         break;
  584                 m = m->m_next;
  585                 if (m == NULL) {                /* last buffer */
  586                         if (space != 0)         /* short last block */
  587                                 CCMP_DECRYPT(i, b, b0, pos, a, space);
  588                         break;
  589                 }
  590                 if (space != 0) {
  591                         uint8_t *pos_next;
  592                         u_int space_next;
  593                         u_int len;
  594 
  595                         /*
  596                          * Block straddles buffers, split references.  We
  597                          * do not handle splits that require >2 buffers
  598                          * since rx'd frames are never badly fragmented
  599                          * because drivers typically recv in clusters.
  600                          */
  601                         pos_next = mtod(m, uint8_t *);
  602                         len = min(data_len, AES_BLOCK_LEN);
  603                         space_next = len > space ? len - space : 0;
  604                         KASSERT(m->m_len >= space_next,
  605                                 ("not enough data in following buffer, "
  606                                 "m_len %u need %u\n", m->m_len, space_next));
  607 
  608                         xor_block(b+space, pos_next, space_next);
  609                         CCMP_DECRYPT(i, b, b0, pos, a, space);
  610                         xor_block(pos_next, b+space, space_next);
  611                         data_len -= len;
  612                         i++;
  613 
  614                         pos = pos_next + space_next;
  615                         space = m->m_len - space_next;
  616                 } else {
  617                         /*
  618                          * Setup for next buffer.
  619                          */
  620                         pos = mtod(m, uint8_t *);
  621                         space = m->m_len;
  622                 }
  623         }
  624         if (memcmp(mic, a, ccmp.ic_trailer) != 0) {
  625                 IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
  626                         "[%s] AES-CCM decrypt failed; MIC mismatch\n",
  627                         ether_sprintf(wh->i_addr2));
  628                 ctx->cc_ic->ic_stats.is_rx_ccmpmic++;
  629                 return 0;
  630         }
  631         return 1;
  632 }
  633 #undef CCMP_DECRYPT
  634 
  635 /*
  636  * Module glue.
  637  */
  638 static int
  639 ccmp_modevent(module_t mod, int type, void *unused)
  640 {
  641         switch (type) {
  642         case MOD_LOAD:
  643                 ieee80211_crypto_register(&ccmp);
  644                 return 0;
  645         case MOD_UNLOAD:
  646         case MOD_QUIESCE:
  647                 if (nrefs) {
  648                         printf("wlan_ccmp: still in use (%u dynamic refs)\n",
  649                                 nrefs);
  650                         return EBUSY;
  651                 }
  652                 if (type == MOD_UNLOAD)
  653                         ieee80211_crypto_unregister(&ccmp);
  654                 return 0;
  655         }
  656         return EINVAL;
  657 }
  658 
  659 static moduledata_t ccmp_mod = {
  660         "wlan_ccmp",
  661         ccmp_modevent,
  662         0
  663 };
  664 DECLARE_MODULE(wlan_ccmp, ccmp_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
  665 MODULE_VERSION(wlan_ccmp, 1);
  666 MODULE_DEPEND(wlan_ccmp, wlan, 1, 1, 1);

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