The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/netipsec/xform_esp.c

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    1 /*      $NetBSD: xform_esp.c,v 1.12 2006/11/16 01:33:49 christos Exp $  */
    2 /*      $FreeBSD: src/sys/netipsec/xform_esp.c,v 1.2.2.1 2003/01/24 05:11:36 sam Exp $  */
    3 /*      $OpenBSD: ip_esp.c,v 1.69 2001/06/26 06:18:59 angelos Exp $ */
    4 
    5 /*
    6  * The authors of this code are John Ioannidis (ji@tla.org),
    7  * Angelos D. Keromytis (kermit@csd.uch.gr) and
    8  * Niels Provos (provos@physnet.uni-hamburg.de).
    9  *
   10  * The original version of this code was written by John Ioannidis
   11  * for BSD/OS in Athens, Greece, in November 1995.
   12  *
   13  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
   14  * by Angelos D. Keromytis.
   15  *
   16  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
   17  * and Niels Provos.
   18  *
   19  * Additional features in 1999 by Angelos D. Keromytis.
   20  *
   21  * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
   22  * Angelos D. Keromytis and Niels Provos.
   23  * Copyright (c) 2001 Angelos D. Keromytis.
   24  *
   25  * Permission to use, copy, and modify this software with or without fee
   26  * is hereby granted, provided that this entire notice is included in
   27  * all copies of any software which is or includes a copy or
   28  * modification of this software.
   29  * You may use this code under the GNU public license if you so wish. Please
   30  * contribute changes back to the authors under this freer than GPL license
   31  * so that we may further the use of strong encryption without limitations to
   32  * all.
   33  *
   34  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
   35  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
   36  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
   37  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
   38  * PURPOSE.
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __KERNEL_RCSID(0, "$NetBSD: xform_esp.c,v 1.12 2006/11/16 01:33:49 christos Exp $");
   43 
   44 #include "opt_inet.h"
   45 #ifdef __FreeBSD__
   46 #include "opt_inet6.h"
   47 #endif
   48 
   49 #include <sys/param.h>
   50 #include <sys/systm.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/socket.h>
   53 #include <sys/syslog.h>
   54 #include <sys/kernel.h>
   55 /*#include <sys/random.h>*/
   56 #include <sys/sysctl.h>
   57 
   58 #include <net/if.h>
   59 
   60 #include <netinet/in.h>
   61 #include <netinet/in_systm.h>
   62 #include <netinet/ip.h>
   63 #include <netinet/ip_ecn.h>
   64 #include <netinet/ip6.h>
   65 
   66 #include <net/route.h>
   67 #include <netipsec/ipsec.h>
   68 #include <netipsec/ah.h>
   69 #include <netipsec/ah_var.h>
   70 #include <netipsec/esp.h>
   71 #include <netipsec/esp_var.h>
   72 #include <netipsec/xform.h>
   73 
   74 #ifdef INET6
   75 #include <netinet6/ip6_var.h>
   76 #include <netipsec/ipsec6.h>
   77 #  ifdef __FreeBSD__
   78 #  include <netinet6/ip6_ecn.h>
   79 #  endif
   80 #endif
   81 
   82 #include <netipsec/key.h>
   83 #include <netipsec/key_debug.h>
   84 
   85 #include <netipsec/ipsec_osdep.h>
   86 
   87 #include <opencrypto/cryptodev.h>
   88 #include <opencrypto/xform.h>
   89 
   90 int     esp_enable = 1;
   91 struct  espstat espstat;
   92 
   93 #ifdef __FreeBSD__
   94 SYSCTL_DECL(_net_inet_esp);
   95 SYSCTL_INT(_net_inet_esp, OID_AUTO,
   96         esp_enable,     CTLFLAG_RW,     &esp_enable,    0, "");
   97 SYSCTL_STRUCT(_net_inet_esp, IPSECCTL_STATS,
   98         stats,          CTLFLAG_RD,     &espstat,       espstat, "");
   99 #endif /* __FreeBSD__ */
  100 
  101 static  int esp_max_ivlen;              /* max iv length over all algorithms */
  102 
  103 static int esp_input_cb(struct cryptop *op);
  104 static int esp_output_cb(struct cryptop *crp);
  105 
  106 /*
  107  * NB: this is public for use by the PF_KEY support.
  108  * NB: if you add support here; be sure to add code to esp_attach below!
  109  */
  110 struct enc_xform *
  111 esp_algorithm_lookup(int alg)
  112 {
  113         if (alg >= ESP_ALG_MAX)
  114                 return NULL;
  115         switch (alg) {
  116         case SADB_EALG_DESCBC:
  117                 return &enc_xform_des;
  118         case SADB_EALG_3DESCBC:
  119                 return &enc_xform_3des;
  120         case SADB_X_EALG_AES:
  121                 return &enc_xform_rijndael128;
  122         case SADB_X_EALG_BLOWFISHCBC:
  123                 return &enc_xform_blf;
  124         case SADB_X_EALG_CAST128CBC:
  125                 return &enc_xform_cast5;
  126         case SADB_X_EALG_SKIPJACK:
  127                 return &enc_xform_skipjack;
  128         case SADB_EALG_NULL:
  129                 return &enc_xform_null;
  130         }
  131         return NULL;
  132 }
  133 
  134 size_t
  135 esp_hdrsiz(struct secasvar *sav)
  136 {
  137         size_t size;
  138 
  139         if (sav != NULL) {
  140                 /*XXX not right for null algorithm--does it matter??*/
  141                 IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
  142                         ("esp_hdrsiz: SA with null xform"));
  143                 if (sav->flags & SADB_X_EXT_OLD)
  144                         size = sizeof (struct esp);
  145                 else
  146                         size = sizeof (struct newesp);
  147                 size += sav->tdb_encalgxform->blocksize + 9;
  148                 /*XXX need alg check???*/
  149                 if (sav->tdb_authalgxform != NULL && sav->replay)
  150                         size += ah_hdrsiz(sav);
  151         } else {
  152                 /*
  153                  *   base header size
  154                  * + max iv length for CBC mode
  155                  * + max pad length
  156                  * + sizeof (pad length field)
  157                  * + sizeof (next header field)
  158                  * + max icv supported.
  159                  */
  160                 size = sizeof (struct newesp) + esp_max_ivlen + 9 + 16;
  161         }
  162         return size;
  163 }
  164 
  165 /*
  166  * esp_init() is called when an SPI is being set up.
  167  */
  168 static int
  169 esp_init(struct secasvar *sav, struct xformsw *xsp)
  170 {
  171         struct enc_xform *txform;
  172         struct cryptoini cria, crie;
  173         int keylen;
  174         int error;
  175 
  176         txform = esp_algorithm_lookup(sav->alg_enc);
  177         if (txform == NULL) {
  178                 DPRINTF(("esp_init: unsupported encryption algorithm %d\n",
  179                         sav->alg_enc));
  180                 return EINVAL;
  181         }
  182         if (sav->key_enc == NULL) {
  183                 DPRINTF(("esp_init: no encoding key for %s algorithm\n",
  184                          txform->name));
  185                 return EINVAL;
  186         }
  187         if ((sav->flags&(SADB_X_EXT_OLD|SADB_X_EXT_IV4B)) == SADB_X_EXT_IV4B) {
  188                 DPRINTF(("esp_init: 4-byte IV not supported with protocol\n"));
  189                 return EINVAL;
  190         }
  191         keylen = _KEYLEN(sav->key_enc);
  192         if (txform->minkey > keylen || keylen > txform->maxkey) {
  193                 DPRINTF(("esp_init: invalid key length %u, must be in "
  194                         "the range [%u..%u] for algorithm %s\n",
  195                         keylen, txform->minkey, txform->maxkey,
  196                         txform->name));
  197                 return EINVAL;
  198         }
  199 
  200         /*
  201          * NB: The null xform needs a non-zero blocksize to keep the
  202          *      crypto code happy but if we use it to set ivlen then
  203          *      the ESP header will be processed incorrectly.  The
  204          *      compromise is to force it to zero here.
  205          */
  206         sav->ivlen = (txform == &enc_xform_null ? 0 : txform->blocksize);
  207         sav->iv = (caddr_t) malloc(sav->ivlen, M_SECA, M_WAITOK);
  208         if (sav->iv == NULL) {
  209                 DPRINTF(("esp_init: no memory for IV\n"));
  210                 return EINVAL;
  211         }
  212         key_randomfill(sav->iv, sav->ivlen);    /*XXX*/
  213 
  214         /*
  215          * Setup AH-related state.
  216          */
  217         if (sav->alg_auth != 0) {
  218                 error = ah_init0(sav, xsp, &cria);
  219                 if (error)
  220                         return error;
  221         }
  222 
  223         /* NB: override anything set in ah_init0 */
  224         sav->tdb_xform = xsp;
  225         sav->tdb_encalgxform = txform;
  226 
  227         /* Initialize crypto session. */
  228         bzero(&crie, sizeof (crie));
  229         crie.cri_alg = sav->tdb_encalgxform->type;
  230         crie.cri_klen = _KEYBITS(sav->key_enc);
  231         crie.cri_key = _KEYBUF(sav->key_enc);
  232         /* XXX Rounds ? */
  233 
  234         if (sav->tdb_authalgxform && sav->tdb_encalgxform) {
  235                 /* init both auth & enc */
  236                 crie.cri_next = &cria;
  237                 error = crypto_newsession(&sav->tdb_cryptoid,
  238                                           &crie, crypto_support);
  239         } else if (sav->tdb_encalgxform) {
  240                 error = crypto_newsession(&sav->tdb_cryptoid,
  241                                           &crie, crypto_support);
  242         } else if (sav->tdb_authalgxform) {
  243                 error = crypto_newsession(&sav->tdb_cryptoid,
  244                                           &cria, crypto_support);
  245         } else {
  246                 /* XXX cannot happen? */
  247                 DPRINTF(("esp_init: no encoding OR authentication xform!\n"));
  248                 error = EINVAL;
  249         }
  250         return error;
  251 }
  252 
  253 /*
  254  * Paranoia.
  255  */
  256 static int
  257 esp_zeroize(struct secasvar *sav)
  258 {
  259         /* NB: ah_zerorize free's the crypto session state */
  260         int error = ah_zeroize(sav);
  261 
  262         if (sav->key_enc)
  263                 bzero(_KEYBUF(sav->key_enc), _KEYLEN(sav->key_enc));
  264         /* NB: sav->iv is freed elsewhere, even though we malloc it! */
  265         sav->tdb_encalgxform = NULL;
  266         sav->tdb_xform = NULL;
  267         return error;
  268 }
  269 
  270 /*
  271  * ESP input processing, called (eventually) through the protocol switch.
  272  */
  273 static int
  274 esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
  275 {
  276         struct auth_hash *esph;
  277         struct enc_xform *espx;
  278         struct tdb_ident *tdbi;
  279         struct tdb_crypto *tc;
  280         int plen, alen, hlen;
  281         struct m_tag *mtag;
  282         struct newesp *esp;
  283 
  284         struct cryptodesc *crde;
  285         struct cryptop *crp;
  286 
  287         IPSEC_SPLASSERT_SOFTNET("esp_input");
  288 
  289         IPSEC_ASSERT(sav != NULL, ("esp_input: null SA"));
  290         IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
  291                 ("esp_input: null encoding xform"));
  292         IPSEC_ASSERT((skip&3) == 0 && (m->m_pkthdr.len&3) == 0,
  293                 ("esp_input: misaligned packet, skip %u pkt len %u",
  294                         skip, m->m_pkthdr.len));
  295 
  296         /* XXX don't pullup, just copy header */
  297         IP6_EXTHDR_GET(esp, struct newesp *, m, skip, sizeof (struct newesp));
  298 
  299         esph = sav->tdb_authalgxform;
  300         espx = sav->tdb_encalgxform;
  301 
  302         /* Determine the ESP header length */
  303         if (sav->flags & SADB_X_EXT_OLD)
  304                 hlen = sizeof (struct esp) + sav->ivlen;
  305         else
  306                 hlen = sizeof (struct newesp) + sav->ivlen;
  307         /* Authenticator hash size */
  308         alen = esph ? AH_HMAC_HASHLEN : 0;
  309 
  310         /*
  311          * Verify payload length is multiple of encryption algorithm
  312          * block size.
  313          *
  314          * NB: This works for the null algorithm because the blocksize
  315          *     is 4 and all packets must be 4-byte aligned regardless
  316          *     of the algorithm.
  317          */
  318         plen = m->m_pkthdr.len - (skip + hlen + alen);
  319         if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
  320                 DPRINTF(("esp_input: "
  321                     "payload of %d octets not a multiple of %d octets,"
  322                     "  SA %s/%08lx\n",
  323                     plen, espx->blocksize,
  324                     ipsec_address(&sav->sah->saidx.dst),
  325                     (u_long) ntohl(sav->spi)));
  326                 espstat.esps_badilen++;
  327                 m_freem(m);
  328                 return EINVAL;
  329         }
  330 
  331         /*
  332          * Check sequence number.
  333          */
  334         if (esph && sav->replay && !ipsec_chkreplay(ntohl(esp->esp_seq), sav)) {
  335                 DPRINTF(("esp_input: packet replay check for %s\n",
  336                     ipsec_logsastr(sav)));      /*XXX*/
  337                 espstat.esps_replay++;
  338                 m_freem(m);
  339                 return ENOBUFS;         /*XXX*/
  340         }
  341 
  342         /* Update the counters */
  343         espstat.esps_ibytes += m->m_pkthdr.len - skip - hlen - alen;
  344 
  345         /* Find out if we've already done crypto */
  346         for (mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, NULL);
  347              mtag != NULL;
  348              mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_CRYPTO_DONE, mtag)) {
  349                 tdbi = (struct tdb_ident *) (mtag + 1);
  350                 if (tdbi->proto == sav->sah->saidx.proto &&
  351                     tdbi->spi == sav->spi &&
  352                     !bcmp(&tdbi->dst, &sav->sah->saidx.dst,
  353                           sizeof(union sockaddr_union)))
  354                         break;
  355         }
  356 
  357         /* Get crypto descriptors */
  358         crp = crypto_getreq(esph && espx ? 2 : 1);
  359         if (crp == NULL) {
  360                 DPRINTF(("esp_input: failed to acquire crypto descriptors\n"));
  361                 espstat.esps_crypto++;
  362                 m_freem(m);
  363                 return ENOBUFS;
  364         }
  365 
  366         /* Get IPsec-specific opaque pointer */
  367         if (esph == NULL || mtag != NULL)
  368                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  369                     M_XDATA, M_NOWAIT|M_ZERO);
  370         else
  371                 tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto) + alen,
  372                     M_XDATA, M_NOWAIT|M_ZERO);
  373         if (tc == NULL) {
  374                 crypto_freereq(crp);
  375                 DPRINTF(("esp_input: failed to allocate tdb_crypto\n"));
  376                 espstat.esps_crypto++;
  377                 m_freem(m);
  378                 return ENOBUFS;
  379         }
  380 
  381         tc->tc_ptr = (caddr_t) mtag;
  382 
  383         if (esph) {
  384                 struct cryptodesc *crda = crp->crp_desc;
  385 
  386                 IPSEC_ASSERT(crda != NULL, ("esp_input: null ah crypto descriptor"));
  387 
  388                 /* Authentication descriptor */
  389                 crda->crd_skip = skip;
  390                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  391                 crda->crd_inject = m->m_pkthdr.len - alen;
  392 
  393                 crda->crd_alg = esph->type;
  394                 crda->crd_key = _KEYBUF(sav->key_auth);
  395                 crda->crd_klen = _KEYBITS(sav->key_auth);
  396 
  397                 /* Copy the authenticator */
  398                 if (mtag == NULL)
  399                         m_copydata(m, m->m_pkthdr.len - alen, alen,
  400                                    (caddr_t) (tc + 1));
  401 
  402                 /* Chain authentication request */
  403                 crde = crda->crd_next;
  404         } else {
  405                 crde = crp->crp_desc;
  406         }
  407 
  408         /* Crypto operation descriptor */
  409         crp->crp_ilen = m->m_pkthdr.len; /* Total input length */
  410         crp->crp_flags = CRYPTO_F_IMBUF;
  411         crp->crp_buf = (caddr_t) m;
  412         crp->crp_callback = esp_input_cb;
  413         crp->crp_sid = sav->tdb_cryptoid;
  414         crp->crp_opaque = (caddr_t) tc;
  415 
  416         /* These are passed as-is to the callback */
  417         tc->tc_spi = sav->spi;
  418         tc->tc_dst = sav->sah->saidx.dst;
  419         tc->tc_proto = sav->sah->saidx.proto;
  420         tc->tc_protoff = protoff;
  421         tc->tc_skip = skip;
  422 
  423         /* Decryption descriptor */
  424         if (espx) {
  425                 IPSEC_ASSERT(crde != NULL, ("esp_input: null esp crypto descriptor"));
  426                 crde->crd_skip = skip + hlen;
  427                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  428                 crde->crd_inject = skip + hlen - sav->ivlen;
  429 
  430                 crde->crd_alg = espx->type;
  431                 crde->crd_key = _KEYBUF(sav->key_enc);
  432                 crde->crd_klen = _KEYBITS(sav->key_enc);
  433                 /* XXX Rounds ? */
  434         }
  435 
  436         if (mtag == NULL)
  437                 return crypto_dispatch(crp);
  438         else
  439                 return esp_input_cb(crp);
  440 }
  441 
  442 #ifdef INET6
  443 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag) do {              \
  444         if (saidx->dst.sa.sa_family == AF_INET6) {                           \
  445                 error = ipsec6_common_input_cb(m, sav, skip, protoff, mtag); \
  446         } else {                                                             \
  447                 error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag); \
  448         }                                                                    \
  449 } while (0)
  450 #else
  451 #define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag)                   \
  452         (error = ipsec4_common_input_cb(m, sav, skip, protoff, mtag))
  453 #endif
  454 
  455 /*
  456  * ESP input callback from the crypto driver.
  457  */
  458 static int
  459 esp_input_cb(struct cryptop *crp)
  460 {
  461         u_int8_t lastthree[3], aalg[AH_HMAC_HASHLEN];
  462         int s, hlen, skip, protoff, error;
  463         struct mbuf *m;
  464         struct cryptodesc *crd;
  465         struct auth_hash *esph;
  466         struct enc_xform *espx;
  467         struct tdb_crypto *tc;
  468         struct m_tag *mtag;
  469         struct secasvar *sav;
  470         struct secasindex *saidx;
  471         caddr_t ptr;
  472 
  473         crd = crp->crp_desc;
  474         IPSEC_ASSERT(crd != NULL, ("esp_input_cb: null crypto descriptor!"));
  475 
  476         tc = (struct tdb_crypto *) crp->crp_opaque;
  477         IPSEC_ASSERT(tc != NULL, ("esp_input_cb: null opaque crypto data area!"));
  478         skip = tc->tc_skip;
  479         protoff = tc->tc_protoff;
  480         mtag = (struct m_tag *) tc->tc_ptr;
  481         m = (struct mbuf *) crp->crp_buf;
  482 
  483         s = splsoftnet();
  484 
  485         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi);
  486         if (sav == NULL) {
  487                 espstat.esps_notdb++;
  488                 DPRINTF(("esp_input_cb: SA expired while in crypto "
  489                     "(SA %s/%08lx proto %u)\n", ipsec_address(&tc->tc_dst),
  490                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  491                 error = ENOBUFS;                /*XXX*/
  492                 goto bad;
  493         }
  494 
  495         saidx = &sav->sah->saidx;
  496         IPSEC_ASSERT(saidx->dst.sa.sa_family == AF_INET ||
  497                 saidx->dst.sa.sa_family == AF_INET6,
  498                 ("ah_input_cb: unexpected protocol family %u",
  499                  saidx->dst.sa.sa_family));
  500 
  501         esph = sav->tdb_authalgxform;
  502         espx = sav->tdb_encalgxform;
  503 
  504         /* Check for crypto errors */
  505         if (crp->crp_etype) {
  506                 /* Reset the session ID */
  507                 if (sav->tdb_cryptoid != 0)
  508                         sav->tdb_cryptoid = crp->crp_sid;
  509 
  510                 if (crp->crp_etype == EAGAIN) {
  511                         KEY_FREESAV(&sav);
  512                         splx(s);
  513                         return crypto_dispatch(crp);
  514                 }
  515 
  516                 espstat.esps_noxform++;
  517                 DPRINTF(("esp_input_cb: crypto error %d\n", crp->crp_etype));
  518                 error = crp->crp_etype;
  519                 goto bad;
  520         }
  521 
  522         /* Shouldn't happen... */
  523         if (m == NULL) {
  524                 espstat.esps_crypto++;
  525                 DPRINTF(("esp_input_cb: bogus returned buffer from crypto\n"));
  526                 error = EINVAL;
  527                 goto bad;
  528         }
  529         espstat.esps_hist[sav->alg_enc]++;
  530 
  531         /* If authentication was performed, check now. */
  532         if (esph != NULL) {
  533                 /*
  534                  * If we have a tag, it means an IPsec-aware NIC did
  535                  * the verification for us.  Otherwise we need to
  536                  * check the authentication calculation.
  537                  */
  538                 ahstat.ahs_hist[sav->alg_auth]++;
  539                 if (mtag == NULL) {
  540                         /* Copy the authenticator from the packet */
  541                         m_copydata(m, m->m_pkthdr.len - esph->authsize,
  542                                 esph->authsize, aalg);
  543 
  544                         ptr = (caddr_t) (tc + 1);
  545 
  546                         /* Verify authenticator */
  547                         if (bcmp(ptr, aalg, esph->authsize) != 0) {
  548                                 DPRINTF(("esp_input_cb: "
  549                     "authentication hash mismatch for packet in SA %s/%08lx\n",
  550                                     ipsec_address(&saidx->dst),
  551                                     (u_long) ntohl(sav->spi)));
  552                                 espstat.esps_badauth++;
  553                                 error = EACCES;
  554                                 goto bad;
  555                         }
  556                 }
  557 
  558                 /* Remove trailing authenticator */
  559                 m_adj(m, -(esph->authsize));
  560         }
  561 
  562         /* Release the crypto descriptors */
  563         free(tc, M_XDATA), tc = NULL;
  564         crypto_freereq(crp), crp = NULL;
  565 
  566         /*
  567          * Packet is now decrypted.
  568          */
  569         m->m_flags |= M_DECRYPTED;
  570 
  571         /*
  572          * Update replay sequence number, if appropriate.
  573          */
  574         if (sav->replay) {
  575                 u_int32_t seq;
  576 
  577                 m_copydata(m, skip + offsetof(struct newesp, esp_seq),
  578                     sizeof (seq), (caddr_t) &seq);
  579                 if (ipsec_updatereplay(ntohl(seq), sav)) {
  580                         DPRINTF(("%s: packet replay check for %s\n", __func__,
  581                             ipsec_logsastr(sav)));
  582                         espstat.esps_replay++;
  583                         error = ENOBUFS;
  584                         goto bad;
  585                 }
  586         }
  587 
  588         /* Determine the ESP header length */
  589         if (sav->flags & SADB_X_EXT_OLD)
  590                 hlen = sizeof (struct esp) + sav->ivlen;
  591         else
  592                 hlen = sizeof (struct newesp) + sav->ivlen;
  593 
  594         /* Remove the ESP header and IV from the mbuf. */
  595         error = m_striphdr(m, skip, hlen);
  596         if (error) {
  597                 espstat.esps_hdrops++;
  598                 DPRINTF(("esp_input_cb: bad mbuf chain, SA %s/%08lx\n",
  599                     ipsec_address(&sav->sah->saidx.dst),
  600                     (u_long) ntohl(sav->spi)));
  601                 goto bad;
  602         }
  603 
  604         /* Save the last three bytes of decrypted data */
  605         m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);
  606 
  607         /* Verify pad length */
  608         if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
  609                 espstat.esps_badilen++;
  610                 DPRINTF(("esp_input_cb: invalid padding length %d "
  611                          "for %u byte packet in SA %s/%08lx\n",
  612                          lastthree[1], m->m_pkthdr.len - skip,
  613                          ipsec_address(&sav->sah->saidx.dst),
  614                          (u_long) ntohl(sav->spi)));
  615                 error = EINVAL;
  616                 goto bad;
  617         }
  618 
  619         /* Verify correct decryption by checking the last padding bytes */
  620         if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
  621                 if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
  622                         espstat.esps_badenc++;
  623                         DPRINTF(("esp_input_cb: decryption failed "
  624                                 "for packet in SA %s/%08lx\n",
  625                                 ipsec_address(&sav->sah->saidx.dst),
  626                                 (u_long) ntohl(sav->spi)));
  627 DPRINTF(("esp_input_cb: %x %x\n", lastthree[0], lastthree[1]));
  628                         error = EINVAL;
  629                         goto bad;
  630                 }
  631         }
  632 
  633         /* Trim the mbuf chain to remove trailing authenticator and padding */
  634         m_adj(m, -(lastthree[1] + 2));
  635 
  636         /* Restore the Next Protocol field */
  637         m = m_copyback_cow(m, protoff, sizeof (u_int8_t), lastthree + 2,
  638                            M_DONTWAIT);
  639 
  640         if (m == NULL) {
  641                 espstat.esps_crypto++;
  642                 DPRINTF(("esp_input_cb: failed to allocate mbuf\n"));
  643                 error = ENOBUFS;
  644                 goto bad;
  645         }
  646 
  647         IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff, mtag);
  648 
  649         KEY_FREESAV(&sav);
  650         splx(s);
  651         return error;
  652 bad:
  653         if (sav)
  654                 KEY_FREESAV(&sav);
  655         splx(s);
  656         if (m != NULL)
  657                 m_freem(m);
  658         if (tc != NULL)
  659                 free(tc, M_XDATA);
  660         if (crp != NULL)
  661                 crypto_freereq(crp);
  662         return error;
  663 }
  664 
  665 /*
  666  * ESP output routine, called by ipsec[46]_process_packet().
  667  */
  668 static int
  669 esp_output(
  670     struct mbuf *m,
  671     struct ipsecrequest *isr,
  672     struct mbuf **mp,
  673     int skip,
  674     int protoff
  675 )
  676 {
  677         struct enc_xform *espx;
  678         struct auth_hash *esph;
  679         int hlen, rlen, plen, padding, blks, alen, i, roff;
  680         struct mbuf *mo = (struct mbuf *) NULL;
  681         struct tdb_crypto *tc;
  682         struct secasvar *sav;
  683         struct secasindex *saidx;
  684         unsigned char *pad;
  685         u_int8_t prot;
  686         int error, maxpacketsize;
  687 
  688         struct cryptodesc *crde = NULL, *crda = NULL;
  689         struct cryptop *crp;
  690 
  691         IPSEC_SPLASSERT_SOFTNET("esp_output");
  692 
  693         sav = isr->sav;
  694         IPSEC_ASSERT(sav != NULL, ("esp_output: null SA"));
  695         esph = sav->tdb_authalgxform;
  696         espx = sav->tdb_encalgxform;
  697         IPSEC_ASSERT(espx != NULL, ("esp_output: null encoding xform"));
  698 
  699         if (sav->flags & SADB_X_EXT_OLD)
  700                 hlen = sizeof (struct esp) + sav->ivlen;
  701         else
  702                 hlen = sizeof (struct newesp) + sav->ivlen;
  703 
  704         rlen = m->m_pkthdr.len - skip;  /* Raw payload length. */
  705         /*
  706          * NB: The null encoding transform has a blocksize of 4
  707          *     so that headers are properly aligned.
  708          */
  709         blks = espx->blocksize;         /* IV blocksize */
  710 
  711         /* XXX clamp padding length a la KAME??? */
  712         padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;
  713         plen = rlen + padding;          /* Padded payload length. */
  714 
  715         if (esph)
  716                 alen = AH_HMAC_HASHLEN;
  717         else
  718                 alen = 0;
  719 
  720         espstat.esps_output++;
  721 
  722         saidx = &sav->sah->saidx;
  723         /* Check for maximum packet size violations. */
  724         switch (saidx->dst.sa.sa_family) {
  725 #ifdef INET
  726         case AF_INET:
  727                 maxpacketsize = IP_MAXPACKET;
  728                 break;
  729 #endif /* INET */
  730 #ifdef INET6
  731         case AF_INET6:
  732                 maxpacketsize = IPV6_MAXPACKET;
  733                 break;
  734 #endif /* INET6 */
  735         default:
  736                 DPRINTF(("esp_output: unknown/unsupported protocol "
  737                     "family %d, SA %s/%08lx\n",
  738                     saidx->dst.sa.sa_family, ipsec_address(&saidx->dst),
  739                     (u_long) ntohl(sav->spi)));
  740                 espstat.esps_nopf++;
  741                 error = EPFNOSUPPORT;
  742                 goto bad;
  743         }
  744         if (skip + hlen + rlen + padding + alen > maxpacketsize) {
  745                 DPRINTF(("esp_output: packet in SA %s/%08lx got too big "
  746                     "(len %u, max len %u)\n",
  747                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi),
  748                     skip + hlen + rlen + padding + alen, maxpacketsize));
  749                 espstat.esps_toobig++;
  750                 error = EMSGSIZE;
  751                 goto bad;
  752         }
  753 
  754         /* Update the counters. */
  755         espstat.esps_obytes += m->m_pkthdr.len - skip;
  756 
  757         m = m_clone(m);
  758         if (m == NULL) {
  759                 DPRINTF(("esp_output: cannot clone mbuf chain, SA %s/%08lx\n",
  760                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  761                 espstat.esps_hdrops++;
  762                 error = ENOBUFS;
  763                 goto bad;
  764         }
  765 
  766         /* Inject ESP header. */
  767         mo = m_makespace(m, skip, hlen, &roff);
  768         if (mo == NULL) {
  769                 DPRINTF(("esp_output: failed to inject %u byte ESP hdr for SA "
  770                     "%s/%08lx\n",
  771                     hlen, ipsec_address(&saidx->dst),
  772                     (u_long) ntohl(sav->spi)));
  773                 espstat.esps_hdrops++;          /* XXX diffs from openbsd */
  774                 error = ENOBUFS;
  775                 goto bad;
  776         }
  777 
  778         /* Initialize ESP header. */
  779         bcopy((caddr_t) &sav->spi, mtod(mo, caddr_t) + roff, sizeof(u_int32_t));
  780         if (sav->replay) {
  781                 u_int32_t replay;
  782 
  783 #ifdef IPSEC_DEBUG
  784                 /* Emulate replay attack when ipsec_replay is TRUE. */
  785                 if (!ipsec_replay)
  786 #endif
  787                         sav->replay->count++;
  788 
  789                 replay = htonl(sav->replay->count);
  790                 bcopy((caddr_t) &replay,
  791                     mtod(mo, caddr_t) + roff + sizeof(u_int32_t),
  792                     sizeof(u_int32_t));
  793         }
  794 
  795         /*
  796          * Add padding -- better to do it ourselves than use the crypto engine,
  797          * although if/when we support compression, we'd have to do that.
  798          */
  799         pad = (u_char *) m_pad(m, padding + alen);
  800         if (pad == NULL) {
  801                 DPRINTF(("esp_output: m_pad failed for SA %s/%08lx\n",
  802                     ipsec_address(&saidx->dst), (u_long) ntohl(sav->spi)));
  803                 m = NULL;               /* NB: free'd by m_pad */
  804                 error = ENOBUFS;
  805                 goto bad;
  806         }
  807 
  808         /*
  809          * Add padding: random, zero, or self-describing.
  810          * XXX catch unexpected setting
  811          */
  812         switch (sav->flags & SADB_X_EXT_PMASK) {
  813         case SADB_X_EXT_PRAND:
  814                 (void) read_random(pad, padding - 2);
  815                 break;
  816         case SADB_X_EXT_PZERO:
  817                 bzero(pad, padding - 2);
  818                 break;
  819         case SADB_X_EXT_PSEQ:
  820                 for (i = 0; i < padding - 2; i++)
  821                         pad[i] = i+1;
  822                 break;
  823         }
  824 
  825         /* Fix padding length and Next Protocol in padding itself. */
  826         pad[padding - 2] = padding - 2;
  827         m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);
  828 
  829         /* Fix Next Protocol in IPv4/IPv6 header. */
  830         prot = IPPROTO_ESP;
  831         m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);
  832 
  833         /* Get crypto descriptors. */
  834         crp = crypto_getreq(esph && espx ? 2 : 1);
  835         if (crp == NULL) {
  836                 DPRINTF(("esp_output: failed to acquire crypto descriptors\n"));
  837                 espstat.esps_crypto++;
  838                 error = ENOBUFS;
  839                 goto bad;
  840         }
  841 
  842         if (espx) {
  843                 crde = crp->crp_desc;
  844                 crda = crde->crd_next;
  845 
  846                 /* Encryption descriptor. */
  847                 crde->crd_skip = skip + hlen;
  848                 crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
  849                 crde->crd_flags = CRD_F_ENCRYPT;
  850                 crde->crd_inject = skip + hlen - sav->ivlen;
  851 
  852                 /* Encryption operation. */
  853                 crde->crd_alg = espx->type;
  854                 crde->crd_key = _KEYBUF(sav->key_enc);
  855                 crde->crd_klen = _KEYBITS(sav->key_enc);
  856                 /* XXX Rounds ? */
  857         } else
  858                 crda = crp->crp_desc;
  859 
  860         /* IPsec-specific opaque crypto info. */
  861         tc = (struct tdb_crypto *) malloc(sizeof(struct tdb_crypto),
  862                 M_XDATA, M_NOWAIT|M_ZERO);
  863         if (tc == NULL) {
  864                 crypto_freereq(crp);
  865                 DPRINTF(("esp_output: failed to allocate tdb_crypto\n"));
  866                 espstat.esps_crypto++;
  867                 error = ENOBUFS;
  868                 goto bad;
  869         }
  870 
  871         /* Callback parameters */
  872         tc->tc_isr = isr;
  873         tc->tc_spi = sav->spi;
  874         tc->tc_dst = saidx->dst;
  875         tc->tc_proto = saidx->proto;
  876 
  877         /* Crypto operation descriptor. */
  878         crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
  879         crp->crp_flags = CRYPTO_F_IMBUF;
  880         crp->crp_buf = (caddr_t) m;
  881         crp->crp_callback = esp_output_cb;
  882         crp->crp_opaque = (caddr_t) tc;
  883         crp->crp_sid = sav->tdb_cryptoid;
  884 
  885         if (esph) {
  886                 /* Authentication descriptor. */
  887                 crda->crd_skip = skip;
  888                 crda->crd_len = m->m_pkthdr.len - (skip + alen);
  889                 crda->crd_inject = m->m_pkthdr.len - alen;
  890 
  891                 /* Authentication operation. */
  892                 crda->crd_alg = esph->type;
  893                 crda->crd_key = _KEYBUF(sav->key_auth);
  894                 crda->crd_klen = _KEYBITS(sav->key_auth);
  895         }
  896 
  897         return crypto_dispatch(crp);
  898 bad:
  899         if (m)
  900                 m_freem(m);
  901         return (error);
  902 }
  903 
  904 /*
  905  * ESP output callback from the crypto driver.
  906  */
  907 static int
  908 esp_output_cb(struct cryptop *crp)
  909 {
  910         struct tdb_crypto *tc;
  911         struct ipsecrequest *isr;
  912         struct secasvar *sav;
  913         struct mbuf *m;
  914         int s, err, error;
  915 
  916         tc = (struct tdb_crypto *) crp->crp_opaque;
  917         IPSEC_ASSERT(tc != NULL, ("esp_output_cb: null opaque data area!"));
  918         m = (struct mbuf *) crp->crp_buf;
  919 
  920         s = splsoftnet();
  921 
  922         isr = tc->tc_isr;
  923         sav = KEY_ALLOCSA(&tc->tc_dst, tc->tc_proto, tc->tc_spi);
  924         if (sav == NULL) {
  925                 espstat.esps_notdb++;
  926                 DPRINTF(("esp_output_cb: SA expired while in crypto "
  927                     "(SA %s/%08lx proto %u)\n", ipsec_address(&tc->tc_dst),
  928                     (u_long) ntohl(tc->tc_spi), tc->tc_proto));
  929                 error = ENOBUFS;                /*XXX*/
  930                 goto bad;
  931         }
  932         IPSEC_ASSERT(isr->sav == sav,
  933                 ("esp_output_cb: SA changed was %p now %p\n", isr->sav, sav));
  934 
  935         /* Check for crypto errors. */
  936         if (crp->crp_etype) {
  937                 /* Reset session ID. */
  938                 if (sav->tdb_cryptoid != 0)
  939                         sav->tdb_cryptoid = crp->crp_sid;
  940 
  941                 if (crp->crp_etype == EAGAIN) {
  942                         KEY_FREESAV(&sav);
  943                         splx(s);
  944                         return crypto_dispatch(crp);
  945                 }
  946 
  947                 espstat.esps_noxform++;
  948                 DPRINTF(("esp_output_cb: crypto error %d\n", crp->crp_etype));
  949                 error = crp->crp_etype;
  950                 goto bad;
  951         }
  952 
  953         /* Shouldn't happen... */
  954         if (m == NULL) {
  955                 espstat.esps_crypto++;
  956                 DPRINTF(("esp_output_cb: bogus returned buffer from crypto\n"));
  957                 error = EINVAL;
  958                 goto bad;
  959         }
  960         espstat.esps_hist[sav->alg_enc]++;
  961         if (sav->tdb_authalgxform != NULL)
  962                 ahstat.ahs_hist[sav->alg_auth]++;
  963 
  964         /* Release crypto descriptors. */
  965         free(tc, M_XDATA);
  966         crypto_freereq(crp);
  967 
  968 #ifdef IPSEC_DEBUG
  969         /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
  970         if (ipsec_integrity) {
  971                 static unsigned char ipseczeroes[AH_HMAC_HASHLEN];
  972                 struct auth_hash *esph;
  973 
  974                 /*
  975                  * Corrupt HMAC if we want to test integrity verification of
  976                  * the other side.
  977                  */
  978                 esph = sav->tdb_authalgxform;
  979                 if (esph !=  NULL) {
  980                         m_copyback(m, m->m_pkthdr.len - AH_HMAC_HASHLEN,
  981                             AH_HMAC_HASHLEN, ipseczeroes);
  982                 }
  983         }
  984 #endif
  985 
  986         /* NB: m is reclaimed by ipsec_process_done. */
  987         err = ipsec_process_done(m, isr);
  988         KEY_FREESAV(&sav);
  989         splx(s);
  990         return err;
  991 bad:
  992         if (sav)
  993                 KEY_FREESAV(&sav);
  994         splx(s);
  995         if (m)
  996                 m_freem(m);
  997         free(tc, M_XDATA);
  998         crypto_freereq(crp);
  999         return error;
 1000 }
 1001 
 1002 static struct xformsw esp_xformsw = {
 1003         XF_ESP,         XFT_CONF|XFT_AUTH,      "IPsec ESP",
 1004         esp_init,       esp_zeroize,            esp_input,
 1005         esp_output,
 1006         NULL,
 1007 };
 1008 
 1009 INITFN void
 1010 esp_attach(void)
 1011 {
 1012 #define MAXIV(xform)                                    \
 1013         if (xform.blocksize > esp_max_ivlen)            \
 1014                 esp_max_ivlen = xform.blocksize         \
 1015 
 1016         esp_max_ivlen = 0;
 1017         MAXIV(enc_xform_des);           /* SADB_EALG_DESCBC */
 1018         MAXIV(enc_xform_3des);          /* SADB_EALG_3DESCBC */
 1019         MAXIV(enc_xform_rijndael128);   /* SADB_X_EALG_AES */
 1020         MAXIV(enc_xform_blf);           /* SADB_X_EALG_BLOWFISHCBC */
 1021         MAXIV(enc_xform_cast5);         /* SADB_X_EALG_CAST128CBC */
 1022         MAXIV(enc_xform_skipjack);      /* SADB_X_EALG_SKIPJACK */
 1023         MAXIV(enc_xform_null);          /* SADB_EALG_NULL */
 1024 
 1025         xform_register(&esp_xformsw);
 1026 #undef MAXIV
 1027 }
 1028 #ifdef __FreeBSD__
 1029 SYSINIT(esp_xform_init, SI_SUB_DRIVERS, SI_ORDER_FIRST, esp_attach, NULL)
 1030 #else
 1031 #endif

Cache object: f094c494548724142925756b338ba668


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