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/11.0/sys/netipsec/ipsec_mbuf.c 298075 2016-04-15 17:30:33Z pfg $
   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/malloc.h>
   38 #include <sys/mbuf.h>
   39 #include <sys/socket.h>
   40 
   41 #include <net/vnet.h>
   42 #include <netinet/in.h>
   43 #include <netipsec/ipsec.h>
   44 
   45 /*
   46  * Make space for a new header of length hlen at skip bytes
   47  * into the packet.  When doing this we allocate new mbufs only
   48  * when absolutely necessary.  The mbuf where the new header
   49  * is to go is returned together with an offset into the mbuf.
   50  * If NULL is returned then the mbuf chain may have been modified;
   51  * the caller is assumed to always free the chain.
   52  */
   53 struct mbuf *
   54 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
   55 {
   56         struct mbuf *m;
   57         unsigned remain;
   58 
   59         IPSEC_ASSERT(m0 != NULL, ("null mbuf"));
   60         IPSEC_ASSERT(hlen < MHLEN, ("hlen too big: %u", hlen));
   61 
   62         for (m = m0; m && skip > m->m_len; m = m->m_next)
   63                 skip -= m->m_len;
   64         if (m == NULL)
   65                 return (NULL);
   66         /*
   67          * At this point skip is the offset into the mbuf m
   68          * where the new header should be placed.  Figure out
   69          * if there's space to insert the new header.  If so,
   70          * and copying the remainder makes sense then do so.
   71          * Otherwise insert a new mbuf in the chain, splitting
   72          * the contents of m as needed.
   73          */
   74         remain = m->m_len - skip;               /* data to move */
   75         if (hlen > M_TRAILINGSPACE(m)) {
   76                 struct mbuf *n0, *n, **np;
   77                 int todo, len, done, alloc;
   78 
   79                 n0 = NULL;
   80                 np = &n0;
   81                 alloc = 0;
   82                 done = 0;
   83                 todo = remain;
   84                 while (todo > 0) {
   85                         if (todo > MHLEN) {
   86                                 n = m_getcl(M_NOWAIT, m->m_type, 0);
   87                                 len = MCLBYTES;
   88                         }
   89                         else {
   90                                 n = m_get(M_NOWAIT, m->m_type);
   91                                 len = MHLEN;
   92                         }
   93                         if (n == NULL) {
   94                                 m_freem(n0);
   95                                 return NULL;
   96                         }
   97                         *np = n;
   98                         np = &n->m_next;
   99                         alloc++;
  100                         len = min(todo, len);
  101                         memcpy(n->m_data, mtod(m, char *) + skip + done, len);
  102                         n->m_len = len;
  103                         done += len;
  104                         todo -= len;
  105                 }
  106 
  107                 if (hlen <= M_TRAILINGSPACE(m) + remain) {
  108                         m->m_len = skip + hlen;
  109                         *off = skip;
  110                         if (n0 != NULL) {
  111                                 *np = m->m_next;
  112                                 m->m_next = n0;
  113                         }
  114                 }
  115                 else {
  116                         n = m_get(M_NOWAIT, m->m_type);
  117                         if (n == NULL) {
  118                                 m_freem(n0);
  119                                 return NULL;
  120                         }
  121                         alloc++;
  122 
  123                         if ((n->m_next = n0) == NULL)
  124                                 np = &n->m_next;
  125                         n0 = n;
  126 
  127                         *np = m->m_next;
  128                         m->m_next = n0;
  129 
  130                         n->m_len = hlen;
  131                         m->m_len = skip;
  132 
  133                         m = n;                  /* header is at front ... */
  134                         *off = 0;               /* ... of new mbuf */
  135                 }
  136                 IPSECSTAT_INC(ips_mbinserted);
  137         } else {
  138                 /*
  139                  * Copy the remainder to the back of the mbuf
  140                  * so there's space to write the new header.
  141                  */
  142                 bcopy(mtod(m, caddr_t) + skip,
  143                       mtod(m, caddr_t) + skip + hlen, remain);
  144                 m->m_len += hlen;
  145                 *off = skip;
  146         }
  147         m0->m_pkthdr.len += hlen;               /* adjust packet length */
  148         return m;
  149 }
  150 
  151 /*
  152  * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
  153  * length is updated, and a pointer to the first byte of the padding
  154  * (which is guaranteed to be all in one mbuf) is returned.
  155  */
  156 caddr_t
  157 m_pad(struct mbuf *m, int n)
  158 {
  159         register struct mbuf *m0, *m1;
  160         register int len, pad;
  161         caddr_t retval;
  162 
  163         if (n <= 0) {  /* No stupid arguments. */
  164                 DPRINTF(("%s: pad length invalid (%d)\n", __func__, n));
  165                 m_freem(m);
  166                 return NULL;
  167         }
  168 
  169         len = m->m_pkthdr.len;
  170         pad = n;
  171         m0 = m;
  172 
  173         while (m0->m_len < len) {
  174                 len -= m0->m_len;
  175                 m0 = m0->m_next;
  176         }
  177 
  178         if (m0->m_len != len) {
  179                 DPRINTF(("%s: length mismatch (should be %d instead of %d)\n",
  180                         __func__, m->m_pkthdr.len,
  181                         m->m_pkthdr.len + m0->m_len - len));
  182 
  183                 m_freem(m);
  184                 return NULL;
  185         }
  186 
  187         /* Check for zero-length trailing mbufs, and find the last one. */
  188         for (m1 = m0; m1->m_next; m1 = m1->m_next) {
  189                 if (m1->m_next->m_len != 0) {
  190                         DPRINTF(("%s: length mismatch (should be %d instead "
  191                                 "of %d)\n", __func__,
  192                                 m->m_pkthdr.len,
  193                                 m->m_pkthdr.len + m1->m_next->m_len));
  194 
  195                         m_freem(m);
  196                         return NULL;
  197                 }
  198 
  199                 m0 = m1->m_next;
  200         }
  201 
  202         if (pad > M_TRAILINGSPACE(m0)) {
  203                 /* Add an mbuf to the chain. */
  204                 MGET(m1, M_NOWAIT, MT_DATA);
  205                 if (m1 == NULL) {
  206                         m_freem(m0);
  207                         DPRINTF(("%s: unable to get extra mbuf\n", __func__));
  208                         return NULL;
  209                 }
  210 
  211                 m0->m_next = m1;
  212                 m0 = m1;
  213                 m0->m_len = 0;
  214         }
  215 
  216         retval = m0->m_data + m0->m_len;
  217         m0->m_len += pad;
  218         m->m_pkthdr.len += pad;
  219 
  220         return retval;
  221 }
  222 
  223 /*
  224  * Remove hlen data at offset skip in the packet.  This is used by
  225  * the protocols strip protocol headers and associated data (e.g. IV,
  226  * authenticator) on input.
  227  */
  228 int
  229 m_striphdr(struct mbuf *m, int skip, int hlen)
  230 {
  231         struct mbuf *m1;
  232         int roff;
  233 
  234         /* Find beginning of header */
  235         m1 = m_getptr(m, skip, &roff);
  236         if (m1 == NULL)
  237                 return (EINVAL);
  238 
  239         /* Remove the header and associated data from the mbuf. */
  240         if (roff == 0) {
  241                 /* The header was at the beginning of the mbuf */
  242                 IPSECSTAT_INC(ips_input_front);
  243                 m_adj(m1, hlen);
  244                 if ((m1->m_flags & M_PKTHDR) == 0)
  245                         m->m_pkthdr.len -= hlen;
  246         } else if (roff + hlen >= m1->m_len) {
  247                 struct mbuf *mo;
  248 
  249                 /*
  250                  * Part or all of the header is at the end of this mbuf,
  251                  * so first let's remove the remainder of the header from
  252                  * the beginning of the remainder of the mbuf chain, if any.
  253                  */
  254                 IPSECSTAT_INC(ips_input_end);
  255                 if (roff + hlen > m1->m_len) {
  256                         /* Adjust the next mbuf by the remainder */
  257                         m_adj(m1->m_next, roff + hlen - m1->m_len);
  258 
  259                         /* The second mbuf is guaranteed not to have a pkthdr... */
  260                         m->m_pkthdr.len -= (roff + hlen - m1->m_len);
  261                 }
  262 
  263                 /* Now, let's unlink the mbuf chain for a second...*/
  264                 mo = m1->m_next;
  265                 m1->m_next = NULL;
  266 
  267                 /* ...and trim the end of the first part of the chain...sick */
  268                 m_adj(m1, -(m1->m_len - roff));
  269                 if ((m1->m_flags & M_PKTHDR) == 0)
  270                         m->m_pkthdr.len -= (m1->m_len - roff);
  271 
  272                 /* Finally, let's relink */
  273                 m1->m_next = mo;
  274         } else {
  275                 /*
  276                  * The header lies in the "middle" of the mbuf; copy
  277                  * the remainder of the mbuf down over the header.
  278                  */
  279                 IPSECSTAT_INC(ips_input_middle);
  280                 bcopy(mtod(m1, u_char *) + roff + hlen,
  281                       mtod(m1, u_char *) + roff,
  282                       m1->m_len - (roff + hlen));
  283                 m1->m_len -= hlen;
  284                 m->m_pkthdr.len -= hlen;
  285         }
  286         return (0);
  287 }
  288 
  289 /*
  290  * Diagnostic routine to check mbuf alignment as required by the
  291  * crypto device drivers (that use DMA).
  292  */
  293 void
  294 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
  295 {
  296         int roff;
  297         struct mbuf *m = m_getptr(m0, off, &roff);
  298         caddr_t addr;
  299 
  300         if (m == NULL)
  301                 return;
  302         printf("%s (off %u len %u): ", where, off, len);
  303         addr = mtod(m, caddr_t) + roff;
  304         do {
  305                 int mlen;
  306 
  307                 if (((uintptr_t) addr) & 3) {
  308                         printf("addr misaligned %p,", addr);
  309                         break;
  310                 }
  311                 mlen = m->m_len;
  312                 if (mlen > len)
  313                         mlen = len;
  314                 len -= mlen;
  315                 if (len && (mlen & 3)) {
  316                         printf("len mismatch %u,", mlen);
  317                         break;
  318                 }
  319                 m = m->m_next;
  320                 addr = m ? mtod(m, caddr_t) : NULL;
  321         } while (m && len > 0);
  322         for (m = m0; m; m = m->m_next)
  323                 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
  324         printf("\n");
  325 }

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