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

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    1 /*      $NetBSD: ipsec_mbuf.c,v 1.11 2008/04/23 06:09:05 thorpej Exp $  */
    2 /*-
    3  * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  * $FreeBSD: /repoman/r/ncvs/src/sys/netipsec/ipsec_mbuf.c,v 1.5.2.2 2003/03/28 20:32:53 sam Exp $
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __KERNEL_RCSID(0, "$NetBSD: ipsec_mbuf.c,v 1.11 2008/04/23 06:09:05 thorpej Exp $");
   32 
   33 /*
   34  * IPsec-specific mbuf routines.
   35  */
   36 
   37 #ifdef __FreeBSD__
   38 #include "opt_param.h"
   39 #endif
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/socket.h>
   45 
   46 #include <net/route.h>
   47 #include <netinet/in.h>
   48 
   49 #include <netipsec/ipsec.h>
   50 #include <netipsec/ipsec_var.h>
   51 #include <netipsec/ipsec_private.h>
   52 
   53 #include <netipsec/ipsec_osdep.h>
   54 #include <net/net_osdep.h>
   55 
   56 extern  struct mbuf *m_getptr(struct mbuf *, int, int *);
   57 
   58 /*
   59  * Create a writable copy of the mbuf chain.  While doing this
   60  * we compact the chain with a goal of producing a chain with
   61  * at most two mbufs.  The second mbuf in this chain is likely
   62  * to be a cluster.  The primary purpose of this work is to create
   63  * a writable packet for encryption, compression, etc.  The
   64  * secondary goal is to linearize the data so the data can be
   65  * passed to crypto hardware in the most efficient manner possible.
   66  */
   67 struct mbuf *
   68 m_clone(struct mbuf *m0)
   69 {
   70         struct mbuf *m, *mprev;
   71         struct mbuf *n, *mfirst, *mlast;
   72         int len, off;
   73 
   74         IPSEC_ASSERT(m0 != NULL, ("m_clone: null mbuf"));
   75 
   76         mprev = NULL;
   77         for (m = m0; m != NULL; m = mprev->m_next) {
   78                 /*
   79                  * Regular mbufs are ignored unless there's a cluster
   80                  * in front of it that we can use to coalesce.  We do
   81                  * the latter mainly so later clusters can be coalesced
   82                  * also w/o having to handle them specially (i.e. convert
   83                  * mbuf+cluster -> cluster).  This optimization is heavily
   84                  * influenced by the assumption that we're running over
   85                  * Ethernet where MCLBYTES is large enough that the max
   86                  * packet size will permit lots of coalescing into a
   87                  * single cluster.  This in turn permits efficient
   88                  * crypto operations, especially when using hardware.
   89                  */
   90                 if ((m->m_flags & M_EXT) == 0) {
   91                         if (mprev && (mprev->m_flags & M_EXT) &&
   92                             m->m_len <= M_TRAILINGSPACE(mprev)) {
   93                                 /* XXX: this ignores mbuf types */
   94                                 memcpy(mtod(mprev, char *) + mprev->m_len,
   95                                        mtod(m, char *), m->m_len);
   96                                 mprev->m_len += m->m_len;
   97                                 mprev->m_next = m->m_next;      /* unlink from chain */
   98                                 m_free(m);                      /* reclaim mbuf */
   99                                 IPSEC_STATINC(IPSEC_STAT_MBCOALESCED);
  100                         } else {
  101                                 mprev = m;
  102                         }
  103                         continue;
  104                 }
  105                 /*
  106                  * Writable mbufs are left alone (for now).  Note
  107                  * that for 4.x systems it's not possible to identify
  108                  * whether or not mbufs with external buffers are
  109                  * writable unless they use clusters.
  110                  */
  111                 if (M_EXT_WRITABLE(m)) {
  112                         mprev = m;
  113                         continue;
  114                 }
  115 
  116                 /*
  117                  * Not writable, replace with a copy or coalesce with
  118                  * the previous mbuf if possible (since we have to copy
  119                  * it anyway, we try to reduce the number of mbufs and
  120                  * clusters so that future work is easier).
  121                  */
  122                 IPSEC_ASSERT(m->m_flags & M_EXT,
  123                         ("m_clone: m_flags 0x%x", m->m_flags));
  124                 /* NB: we only coalesce into a cluster or larger */
  125                 if (mprev != NULL && (mprev->m_flags & M_EXT) &&
  126                     m->m_len <= M_TRAILINGSPACE(mprev)) {
  127                         /* XXX: this ignores mbuf types */
  128                         memcpy(mtod(mprev, char *) + mprev->m_len,
  129                                mtod(m, char *), m->m_len);
  130                         mprev->m_len += m->m_len;
  131                         mprev->m_next = m->m_next;      /* unlink from chain */
  132                         m_free(m);                      /* reclaim mbuf */
  133                         IPSEC_STATINC(IPSEC_STAT_CLCOALESCED);
  134                         continue;
  135                 }
  136 
  137                 /*
  138                  * Allocate new space to hold the copy...
  139                  */
  140                 /* XXX why can M_PKTHDR be set past the first mbuf? */
  141                 if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
  142                         /*
  143                          * NB: if a packet header is present we must
  144                          * allocate the mbuf separately from any cluster
  145                          * because M_MOVE_PKTHDR will smash the data
  146                          * pointer and drop the M_EXT marker.
  147                          */
  148                         MGETHDR(n, M_DONTWAIT, m->m_type);
  149                         if (n == NULL) {
  150                                 m_freem(m0);
  151                                 return (NULL);
  152                         }
  153                         M_MOVE_PKTHDR(n, m);
  154                         MCLGET(n, M_DONTWAIT);
  155                         if ((n->m_flags & M_EXT) == 0) {
  156                                 m_free(n);
  157                                 m_freem(m0);
  158                                 return (NULL);
  159                         }
  160                 } else {
  161                         n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
  162                         if (n == NULL) {
  163                                 m_freem(m0);
  164                                 return (NULL);
  165                         }
  166                 }
  167                 /*
  168                  * ... and copy the data.  We deal with jumbo mbufs
  169                  * (i.e. m_len > MCLBYTES) by splitting them into
  170                  * clusters.  We could just malloc a buffer and make
  171                  * it external but too many device drivers don't know
  172                  * how to break up the non-contiguous memory when
  173                  * doing DMA.
  174                  */
  175                 len = m->m_len;
  176                 off = 0;
  177                 mfirst = n;
  178                 mlast = NULL;
  179                 for (;;) {
  180                         int cc = min(len, MCLBYTES);
  181                         memcpy(mtod(n, char *), mtod(m, char *) + off, cc);
  182                         n->m_len = cc;
  183                         if (mlast != NULL)
  184                                 mlast->m_next = n;
  185                         mlast = n;
  186                         IPSEC_STATINC(IPSEC_STAT_CLCOPIED);
  187 
  188                         len -= cc;
  189                         if (len <= 0)
  190                                 break;
  191                         off += cc;
  192 
  193                         n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
  194                         if (n == NULL) {
  195                                 m_freem(mfirst);
  196                                 m_freem(m0);
  197                                 return (NULL);
  198                         }
  199                 }
  200                 n->m_next = m->m_next;
  201                 if (mprev == NULL)
  202                         m0 = mfirst;            /* new head of chain */
  203                 else
  204                         mprev->m_next = mfirst; /* replace old mbuf */
  205                 m_free(m);                      /* release old mbuf */
  206                 mprev = mfirst;
  207         }
  208         return (m0);
  209 }
  210 
  211 /*
  212  * Make space for a new header of length hlen at skip bytes
  213  * into the packet.  When doing this we allocate new mbufs only
  214  * when absolutely necessary.  The mbuf where the new header
  215  * is to go is returned together with an offset into the mbuf.
  216  * If NULL is returned then the mbuf chain may have been modified;
  217  * the caller is assumed to always free the chain.
  218  */
  219 struct mbuf *
  220 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
  221 {
  222         struct mbuf *m;
  223         unsigned remain;
  224 
  225         IPSEC_ASSERT(m0 != NULL, ("m_dmakespace: null mbuf"));
  226         IPSEC_ASSERT(hlen < MHLEN, ("m_makespace: hlen too big: %u", hlen));
  227 
  228         for (m = m0; m && skip > m->m_len; m = m->m_next)
  229                 skip -= m->m_len;
  230         if (m == NULL)
  231                 return (NULL);
  232         /*
  233          * At this point skip is the offset into the mbuf m
  234          * where the new header should be placed.  Figure out
  235          * if there's space to insert the new header.  If so,
  236          * and copying the remainder makese sense then do so.
  237          * Otherwise insert a new mbuf in the chain, splitting
  238          * the contents of m as needed.
  239          */
  240         remain = m->m_len - skip;               /* data to move */
  241         if (hlen > M_TRAILINGSPACE(m)) {
  242                 struct mbuf *n0, *n, **np;
  243                 int todo, len, done, alloc;
  244 
  245                 n0 = NULL;
  246                 np = &n0;
  247                 alloc = 0;
  248                 done = 0;
  249                 todo = remain;
  250                 while (todo > 0) {
  251                         if (todo > MHLEN) {
  252                                 n = m_getcl(M_DONTWAIT, m->m_type, 0);
  253                                 len = MCLBYTES;
  254                         }
  255                         else {
  256                                 n = m_get(M_DONTWAIT, m->m_type);
  257                                 len = MHLEN;
  258                         }
  259                         if (n == NULL) {
  260                                 m_freem(n0);
  261                                 return NULL;
  262                         }
  263                         *np = n;
  264                         np = &n->m_next;
  265                         alloc++;
  266                         len = min(todo, len);
  267                         memcpy(n->m_data, mtod(m, char *) + skip + done, len);
  268                         n->m_len = len;
  269                         done += len;
  270                         todo -= len;
  271                 }
  272 
  273                 if (hlen <= M_TRAILINGSPACE(m) + remain) {
  274                         m->m_len = skip + hlen;
  275                         *off = skip;
  276                         if (n0 != NULL) {
  277                                 *np = m->m_next;
  278                                 m->m_next = n0;
  279                         }
  280                 }
  281                 else {
  282                         n = m_get(M_DONTWAIT, m->m_type);
  283                         if (n == NULL) {
  284                                 m_freem(n0);
  285                                 return NULL;
  286                         }
  287                         alloc++;
  288 
  289                         if ((n->m_next = n0) == NULL)
  290                                 np = &n->m_next;
  291                         n0 = n;
  292 
  293                         *np = m->m_next;
  294                         m->m_next = n0;
  295 
  296                         n->m_len = hlen;
  297                         m->m_len = skip;
  298 
  299                         m = n;                  /* header is at front ... */
  300                         *off = 0;               /* ... of new mbuf */
  301                 }
  302 
  303                 IPSEC_STATADD(IPSEC_STAT_MBINSERTED, alloc);
  304         } else {
  305                 /*
  306                  * Copy the remainder to the back of the mbuf
  307                  * so there's space to write the new header.
  308                  */
  309                 /* XXX can this be memcpy? does it handle overlap? */
  310                 ovbcopy(mtod(m, char *) + skip,
  311                         mtod(m, char *) + skip + hlen, remain);
  312                 m->m_len += hlen;
  313                 *off = skip;
  314         }
  315         m0->m_pkthdr.len += hlen;               /* adjust packet length */
  316         return m;
  317 }
  318 
  319 /*
  320  * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
  321  * length is updated, and a pointer to the first byte of the padding
  322  * (which is guaranteed to be all in one mbuf) is returned.
  323  */
  324 void *
  325 m_pad(struct mbuf *m, int n)
  326 {
  327         register struct mbuf *m0, *m1;
  328         register int len, pad;
  329         void *retval;
  330 
  331         if (n <= 0) {  /* No stupid arguments. */
  332                 DPRINTF(("m_pad: pad length invalid (%d)\n", n));
  333                 m_freem(m);
  334                 return NULL;
  335         }
  336 
  337         len = m->m_pkthdr.len;
  338         pad = n;
  339         m0 = m;
  340 
  341         while (m0->m_len < len) {
  342 IPSEC_ASSERT(m0->m_next != NULL, ("m_pad: m0 null, len %u m_len %u", len, m0->m_len));/*XXX*/
  343                 len -= m0->m_len;
  344                 m0 = m0->m_next;
  345         }
  346 
  347         if (m0->m_len != len) {
  348                 DPRINTF(("m_pad: length mismatch (should be %d instead of %d)\n",
  349                     m->m_pkthdr.len, m->m_pkthdr.len + m0->m_len - len));
  350 
  351                 m_freem(m);
  352                 return NULL;
  353         }
  354 
  355         /* Check for zero-length trailing mbufs, and find the last one. */
  356         for (m1 = m0; m1->m_next; m1 = m1->m_next) {
  357                 if (m1->m_next->m_len != 0) {
  358                         DPRINTF(("m_pad: length mismatch (should be %d "
  359                             "instead of %d)\n",
  360                             m->m_pkthdr.len,
  361                             m->m_pkthdr.len + m1->m_next->m_len));
  362 
  363                         m_freem(m);
  364                         return NULL;
  365                 }
  366 
  367                 m0 = m1->m_next;
  368         }
  369 
  370         if (pad > M_TRAILINGSPACE(m0)) {
  371                 /* Add an mbuf to the chain. */
  372                 MGET(m1, M_DONTWAIT, MT_DATA);
  373                 if (m1 == 0) {
  374                         m_freem(m0);
  375                         DPRINTF(("m_pad: unable to get extra mbuf\n"));
  376                         return NULL;
  377                 }
  378 
  379                 m0->m_next = m1;
  380                 m0 = m1;
  381                 m0->m_len = 0;
  382         }
  383 
  384         retval = m0->m_data + m0->m_len;
  385         m0->m_len += pad;
  386         m->m_pkthdr.len += pad;
  387 
  388         return retval;
  389 }
  390 
  391 /*
  392  * Remove hlen data at offset skip in the packet.  This is used by
  393  * the protocols strip protocol headers and associated data (e.g. IV,
  394  * authenticator) on input.
  395  */
  396 int
  397 m_striphdr(struct mbuf *m, int skip, int hlen)
  398 {
  399         struct mbuf *m1;
  400         int roff;
  401 
  402         /* Find beginning of header */
  403         m1 = m_getptr(m, skip, &roff);
  404         if (m1 == NULL)
  405                 return (EINVAL);
  406 
  407         /* Remove the header and associated data from the mbuf. */
  408         if (roff == 0) {
  409                 /* The header was at the beginning of the mbuf */
  410                 IPSEC_STATINC(IPSEC_STAT_INPUT_FRONT);
  411                 m_adj(m1, hlen);
  412                 if ((m1->m_flags & M_PKTHDR) == 0)
  413                         m->m_pkthdr.len -= hlen;
  414         } else if (roff + hlen >= m1->m_len) {
  415                 struct mbuf *mo;
  416 
  417                 /*
  418                  * Part or all of the header is at the end of this mbuf,
  419                  * so first let's remove the remainder of the header from
  420                  * the beginning of the remainder of the mbuf chain, if any.
  421                  */
  422                 IPSEC_STATINC(IPSEC_STAT_INPUT_END);
  423                 if (roff + hlen > m1->m_len) {
  424                         /* Adjust the next mbuf by the remainder */
  425                         m_adj(m1->m_next, roff + hlen - m1->m_len);
  426 
  427                         /* The second mbuf is guaranteed not to have a pkthdr... */
  428                         m->m_pkthdr.len -= (roff + hlen - m1->m_len);
  429                 }
  430 
  431                 /* Now, let's unlink the mbuf chain for a second...*/
  432                 mo = m1->m_next;
  433                 m1->m_next = NULL;
  434 
  435                 /* ...and trim the end of the first part of the chain...sick */
  436                 m_adj(m1, -(m1->m_len - roff));
  437                 if ((m1->m_flags & M_PKTHDR) == 0)
  438                         m->m_pkthdr.len -= (m1->m_len - roff);
  439 
  440                 /* Finally, let's relink */
  441                 m1->m_next = mo;
  442         } else {
  443                 /*
  444                  * The header lies in the "middle" of the mbuf; copy
  445                  * the remainder of the mbuf down over the header.
  446                  */
  447                 IPSEC_STATINC(IPSEC_STAT_INPUT_MIDDLE);
  448                 ovbcopy(mtod(m1, u_char *) + roff + hlen,
  449                       mtod(m1, u_char *) + roff,
  450                       m1->m_len - (roff + hlen));
  451                 m1->m_len -= hlen;
  452                 m->m_pkthdr.len -= hlen;
  453         }
  454         return (0);
  455 }
  456 
  457 /*
  458  * Diagnostic routine to check mbuf alignment as required by the
  459  * crypto device drivers (that use DMA).
  460  */
  461 void
  462 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
  463 {
  464         int roff;
  465         struct mbuf *m = m_getptr(m0, off, &roff);
  466         void *addr;
  467 
  468         if (m == NULL)
  469                 return;
  470         printf("%s (off %u len %u): ", where, off, len);
  471         addr = mtod(m, char *) + roff;
  472         do {
  473                 int mlen;
  474 
  475                 if (((uintptr_t) addr) & 3) {
  476                         printf("addr misaligned %p,", addr);
  477                         break;
  478                 }
  479                 mlen = m->m_len;
  480                 if (mlen > len)
  481                         mlen = len;
  482                 len -= mlen;
  483                 if (len && (mlen & 3)) {
  484                         printf("len mismatch %u,", mlen);
  485                         break;
  486                 }
  487                 m = m->m_next;
  488                 addr = m ? mtod(m, void *) : NULL;
  489         } while (m && len > 0);
  490         for (m = m0; m; m = m->m_next)
  491                 printf(" [%p:%u]", mtod(m, void *), m->m_len);
  492         printf("\n");
  493 }

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