The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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 /*-
    2  * Copyright (c) 2002, 2003 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  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: releng/9.2/sys/netipsec/ipsec_mbuf.c 252692 2013-07-04 08:57:13Z ae $
   27  */
   28 
   29 /*
   30  * IPsec-specific mbuf routines.
   31  */
   32 
   33 #include "opt_param.h"
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/mbuf.h>
   38 #include <sys/socket.h>
   39 
   40 #include <net/route.h>
   41 #include <net/vnet.h>
   42 
   43 #include <netinet/in.h>
   44 
   45 #include <netipsec/ipsec.h>
   46 
   47 /*
   48  * Make space for a new header of length hlen at skip bytes
   49  * into the packet.  When doing this we allocate new mbufs only
   50  * when absolutely necessary.  The mbuf where the new header
   51  * is to go is returned together with an offset into the mbuf.
   52  * If NULL is returned then the mbuf chain may have been modified;
   53  * the caller is assumed to always free the chain.
   54  */
   55 struct mbuf *
   56 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
   57 {
   58         struct mbuf *m;
   59         unsigned remain;
   60 
   61         IPSEC_ASSERT(m0 != NULL, ("null mbuf"));
   62         IPSEC_ASSERT(hlen < MHLEN, ("hlen too big: %u", hlen));
   63 
   64         for (m = m0; m && skip > m->m_len; m = m->m_next)
   65                 skip -= m->m_len;
   66         if (m == NULL)
   67                 return (NULL);
   68         /*
   69          * At this point skip is the offset into the mbuf m
   70          * where the new header should be placed.  Figure out
   71          * if there's space to insert the new header.  If so,
   72          * and copying the remainder makes sense then do so.
   73          * Otherwise insert a new mbuf in the chain, splitting
   74          * the contents of m as needed.
   75          */
   76         remain = m->m_len - skip;               /* data to move */
   77         if (hlen > M_TRAILINGSPACE(m)) {
   78                 struct mbuf *n0, *n, **np;
   79                 int todo, len, done, alloc;
   80 
   81                 n0 = NULL;
   82                 np = &n0;
   83                 alloc = 0;
   84                 done = 0;
   85                 todo = remain;
   86                 while (todo > 0) {
   87                         if (todo > MHLEN) {
   88                                 n = m_getcl(M_DONTWAIT, m->m_type, 0);
   89                                 len = MCLBYTES;
   90                         }
   91                         else {
   92                                 n = m_get(M_DONTWAIT, m->m_type);
   93                                 len = MHLEN;
   94                         }
   95                         if (n == NULL) {
   96                                 m_freem(n0);
   97                                 return NULL;
   98                         }
   99                         *np = n;
  100                         np = &n->m_next;
  101                         alloc++;
  102                         len = min(todo, len);
  103                         memcpy(n->m_data, mtod(m, char *) + skip + done, len);
  104                         n->m_len = len;
  105                         done += len;
  106                         todo -= len;
  107                 }
  108 
  109                 if (hlen <= M_TRAILINGSPACE(m) + remain) {
  110                         m->m_len = skip + hlen;
  111                         *off = skip;
  112                         if (n0 != NULL) {
  113                                 *np = m->m_next;
  114                                 m->m_next = n0;
  115                         }
  116                 }
  117                 else {
  118                         n = m_get(M_DONTWAIT, m->m_type);
  119                         if (n == NULL) {
  120                                 m_freem(n0);
  121                                 return NULL;
  122                         }
  123                         alloc++;
  124 
  125                         if ((n->m_next = n0) == NULL)
  126                                 np = &n->m_next;
  127                         n0 = n;
  128 
  129                         *np = m->m_next;
  130                         m->m_next = n0;
  131 
  132                         n->m_len = hlen;
  133                         m->m_len = skip;
  134 
  135                         m = n;                  /* header is at front ... */
  136                         *off = 0;               /* ... of new mbuf */
  137                 }
  138                 IPSECSTAT_INC(ips_mbinserted);
  139         } else {
  140                 /*
  141                  * Copy the remainder to the back of the mbuf
  142                  * so there's space to write the new header.
  143                  */
  144                 bcopy(mtod(m, caddr_t) + skip,
  145                       mtod(m, caddr_t) + skip + hlen, remain);
  146                 m->m_len += hlen;
  147                 *off = skip;
  148         }
  149         m0->m_pkthdr.len += hlen;               /* adjust packet length */
  150         return m;
  151 }
  152 
  153 /*
  154  * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
  155  * length is updated, and a pointer to the first byte of the padding
  156  * (which is guaranteed to be all in one mbuf) is returned.
  157  */
  158 caddr_t
  159 m_pad(struct mbuf *m, int n)
  160 {
  161         register struct mbuf *m0, *m1;
  162         register int len, pad;
  163         caddr_t retval;
  164 
  165         if (n <= 0) {  /* No stupid arguments. */
  166                 DPRINTF(("%s: pad length invalid (%d)\n", __func__, n));
  167                 m_freem(m);
  168                 return NULL;
  169         }
  170 
  171         len = m->m_pkthdr.len;
  172         pad = n;
  173         m0 = m;
  174 
  175         while (m0->m_len < len) {
  176                 len -= m0->m_len;
  177                 m0 = m0->m_next;
  178         }
  179 
  180         if (m0->m_len != len) {
  181                 DPRINTF(("%s: length mismatch (should be %d instead of %d)\n",
  182                         __func__, m->m_pkthdr.len,
  183                         m->m_pkthdr.len + m0->m_len - len));
  184 
  185                 m_freem(m);
  186                 return NULL;
  187         }
  188 
  189         /* Check for zero-length trailing mbufs, and find the last one. */
  190         for (m1 = m0; m1->m_next; m1 = m1->m_next) {
  191                 if (m1->m_next->m_len != 0) {
  192                         DPRINTF(("%s: length mismatch (should be %d instead "
  193                                 "of %d)\n", __func__,
  194                                 m->m_pkthdr.len,
  195                                 m->m_pkthdr.len + m1->m_next->m_len));
  196 
  197                         m_freem(m);
  198                         return NULL;
  199                 }
  200 
  201                 m0 = m1->m_next;
  202         }
  203 
  204         if (pad > M_TRAILINGSPACE(m0)) {
  205                 /* Add an mbuf to the chain. */
  206                 MGET(m1, M_DONTWAIT, MT_DATA);
  207                 if (m1 == 0) {
  208                         m_freem(m0);
  209                         DPRINTF(("%s: unable to get extra mbuf\n", __func__));
  210                         return NULL;
  211                 }
  212 
  213                 m0->m_next = m1;
  214                 m0 = m1;
  215                 m0->m_len = 0;
  216         }
  217 
  218         retval = m0->m_data + m0->m_len;
  219         m0->m_len += pad;
  220         m->m_pkthdr.len += pad;
  221 
  222         return retval;
  223 }
  224 
  225 /*
  226  * Remove hlen data at offset skip in the packet.  This is used by
  227  * the protocols strip protocol headers and associated data (e.g. IV,
  228  * authenticator) on input.
  229  */
  230 int
  231 m_striphdr(struct mbuf *m, int skip, int hlen)
  232 {
  233         struct mbuf *m1;
  234         int roff;
  235 
  236         /* Find beginning of header */
  237         m1 = m_getptr(m, skip, &roff);
  238         if (m1 == NULL)
  239                 return (EINVAL);
  240 
  241         /* Remove the header and associated data from the mbuf. */
  242         if (roff == 0) {
  243                 /* The header was at the beginning of the mbuf */
  244                 IPSECSTAT_INC(ips_input_front);
  245                 m_adj(m1, hlen);
  246                 if ((m1->m_flags & M_PKTHDR) == 0)
  247                         m->m_pkthdr.len -= hlen;
  248         } else if (roff + hlen >= m1->m_len) {
  249                 struct mbuf *mo;
  250 
  251                 /*
  252                  * Part or all of the header is at the end of this mbuf,
  253                  * so first let's remove the remainder of the header from
  254                  * the beginning of the remainder of the mbuf chain, if any.
  255                  */
  256                 IPSECSTAT_INC(ips_input_end);
  257                 if (roff + hlen > m1->m_len) {
  258                         /* Adjust the next mbuf by the remainder */
  259                         m_adj(m1->m_next, roff + hlen - m1->m_len);
  260 
  261                         /* The second mbuf is guaranteed not to have a pkthdr... */
  262                         m->m_pkthdr.len -= (roff + hlen - m1->m_len);
  263                 }
  264 
  265                 /* Now, let's unlink the mbuf chain for a second...*/
  266                 mo = m1->m_next;
  267                 m1->m_next = NULL;
  268 
  269                 /* ...and trim the end of the first part of the chain...sick */
  270                 m_adj(m1, -(m1->m_len - roff));
  271                 if ((m1->m_flags & M_PKTHDR) == 0)
  272                         m->m_pkthdr.len -= (m1->m_len - roff);
  273 
  274                 /* Finally, let's relink */
  275                 m1->m_next = mo;
  276         } else {
  277                 /*
  278                  * The header lies in the "middle" of the mbuf; copy
  279                  * the remainder of the mbuf down over the header.
  280                  */
  281                 IPSECSTAT_INC(ips_input_middle);
  282                 bcopy(mtod(m1, u_char *) + roff + hlen,
  283                       mtod(m1, u_char *) + roff,
  284                       m1->m_len - (roff + hlen));
  285                 m1->m_len -= hlen;
  286                 m->m_pkthdr.len -= hlen;
  287         }
  288         return (0);
  289 }
  290 
  291 /*
  292  * Diagnostic routine to check mbuf alignment as required by the
  293  * crypto device drivers (that use DMA).
  294  */
  295 void
  296 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
  297 {
  298         int roff;
  299         struct mbuf *m = m_getptr(m0, off, &roff);
  300         caddr_t addr;
  301 
  302         if (m == NULL)
  303                 return;
  304         printf("%s (off %u len %u): ", where, off, len);
  305         addr = mtod(m, caddr_t) + roff;
  306         do {
  307                 int mlen;
  308 
  309                 if (((uintptr_t) addr) & 3) {
  310                         printf("addr misaligned %p,", addr);
  311                         break;
  312                 }
  313                 mlen = m->m_len;
  314                 if (mlen > len)
  315                         mlen = len;
  316                 len -= mlen;
  317                 if (len && (mlen & 3)) {
  318                         printf("len mismatch %u,", mlen);
  319                         break;
  320                 }
  321                 m = m->m_next;
  322                 addr = m ? mtod(m, caddr_t) : NULL;
  323         } while (m && len > 0);
  324         for (m = m0; m; m = m->m_next)
  325                 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
  326         printf("\n");
  327 }

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