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/11.2/sys/netipsec/ipsec_mbuf.c 333207 2018-05-03 08:17:12Z ae $
   27  */
   28 
   29 /*
   30  * IPsec-specific mbuf routines.
   31  */
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/malloc.h>
   36 #include <sys/mbuf.h>
   37 #include <sys/socket.h>
   38 
   39 #include <net/vnet.h>
   40 #include <netinet/in.h>
   41 #include <netipsec/ipsec.h>
   42 
   43 /*
   44  * Make space for a new header of length hlen at skip bytes
   45  * into the packet.  When doing this we allocate new mbufs only
   46  * when absolutely necessary.  The mbuf where the new header
   47  * is to go is returned together with an offset into the mbuf.
   48  * If NULL is returned then the mbuf chain may have been modified;
   49  * the caller is assumed to always free the chain.
   50  */
   51 struct mbuf *
   52 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
   53 {
   54         struct mbuf *m;
   55         unsigned remain;
   56 
   57         IPSEC_ASSERT(m0 != NULL, ("null mbuf"));
   58         IPSEC_ASSERT(hlen < MHLEN, ("hlen too big: %u", hlen));
   59 
   60         for (m = m0; m && skip > m->m_len; m = m->m_next)
   61                 skip -= m->m_len;
   62         if (m == NULL)
   63                 return (NULL);
   64         /*
   65          * At this point skip is the offset into the mbuf m
   66          * where the new header should be placed.  Figure out
   67          * if there's space to insert the new header.  If so,
   68          * and copying the remainder makes sense then do so.
   69          * Otherwise insert a new mbuf in the chain, splitting
   70          * the contents of m as needed.
   71          */
   72         remain = m->m_len - skip;               /* data to move */
   73         if (remain > skip &&
   74             hlen + max_linkhdr < M_LEADINGSPACE(m)) {
   75                 /*
   76                  * mbuf has enough free space at the beginning.
   77                  * XXX: which operation is the most heavy - copying of
   78                  *      possible several hundred of bytes or allocation
   79                  *      of new mbuf? We can remove max_linkhdr check
   80                  *      here, but it is possible that this will lead
   81                  *      to allocation of new mbuf in Layer 2 code.
   82                  */
   83                 m->m_data -= hlen;
   84                 bcopy(mtodo(m, hlen), mtod(m, caddr_t), skip);
   85                 m->m_len += hlen;
   86                 *off = skip;
   87         } else if (hlen > M_TRAILINGSPACE(m)) {
   88                 struct mbuf *n0, *n, **np;
   89                 int todo, len, done, alloc;
   90 
   91                 n0 = NULL;
   92                 np = &n0;
   93                 alloc = 0;
   94                 done = 0;
   95                 todo = remain;
   96                 while (todo > 0) {
   97                         if (todo > MHLEN) {
   98                                 n = m_getcl(M_NOWAIT, m->m_type, 0);
   99                                 len = MCLBYTES;
  100                         }
  101                         else {
  102                                 n = m_get(M_NOWAIT, m->m_type);
  103                                 len = MHLEN;
  104                         }
  105                         if (n == NULL) {
  106                                 m_freem(n0);
  107                                 return NULL;
  108                         }
  109                         *np = n;
  110                         np = &n->m_next;
  111                         alloc++;
  112                         len = min(todo, len);
  113                         memcpy(n->m_data, mtod(m, char *) + skip + done, len);
  114                         n->m_len = len;
  115                         done += len;
  116                         todo -= len;
  117                 }
  118 
  119                 if (hlen <= M_TRAILINGSPACE(m) + remain) {
  120                         m->m_len = skip + hlen;
  121                         *off = skip;
  122                         if (n0 != NULL) {
  123                                 *np = m->m_next;
  124                                 m->m_next = n0;
  125                         }
  126                 }
  127                 else {
  128                         n = m_get(M_NOWAIT, m->m_type);
  129                         if (n == NULL) {
  130                                 m_freem(n0);
  131                                 return NULL;
  132                         }
  133                         alloc++;
  134 
  135                         if ((n->m_next = n0) == NULL)
  136                                 np = &n->m_next;
  137                         n0 = n;
  138 
  139                         *np = m->m_next;
  140                         m->m_next = n0;
  141 
  142                         n->m_len = hlen;
  143                         m->m_len = skip;
  144 
  145                         m = n;                  /* header is at front ... */
  146                         *off = 0;               /* ... of new mbuf */
  147                 }
  148                 IPSECSTAT_INC(ips_mbinserted);
  149         } else {
  150                 /*
  151                  * Copy the remainder to the back of the mbuf
  152                  * so there's space to write the new header.
  153                  */
  154                 bcopy(mtod(m, caddr_t) + skip,
  155                     mtod(m, caddr_t) + skip + hlen, remain);
  156                 m->m_len += hlen;
  157                 *off = skip;
  158         }
  159         m0->m_pkthdr.len += hlen;               /* adjust packet length */
  160         return m;
  161 }
  162 
  163 /*
  164  * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
  165  * length is updated, and a pointer to the first byte of the padding
  166  * (which is guaranteed to be all in one mbuf) is returned.
  167  */
  168 caddr_t
  169 m_pad(struct mbuf *m, int n)
  170 {
  171         struct mbuf *m0, *m1;
  172         int len, pad;
  173         caddr_t retval;
  174 
  175         if (n <= 0) {  /* No stupid arguments. */
  176                 DPRINTF(("%s: pad length invalid (%d)\n", __func__, n));
  177                 m_freem(m);
  178                 return NULL;
  179         }
  180 
  181         len = m->m_pkthdr.len;
  182         pad = n;
  183         m0 = m;
  184 
  185         while (m0->m_len < len) {
  186                 len -= m0->m_len;
  187                 m0 = m0->m_next;
  188         }
  189 
  190         if (m0->m_len != len) {
  191                 DPRINTF(("%s: length mismatch (should be %d instead of %d)\n",
  192                         __func__, m->m_pkthdr.len,
  193                         m->m_pkthdr.len + m0->m_len - len));
  194 
  195                 m_freem(m);
  196                 return NULL;
  197         }
  198 
  199         /* Check for zero-length trailing mbufs, and find the last one. */
  200         for (m1 = m0; m1->m_next; m1 = m1->m_next) {
  201                 if (m1->m_next->m_len != 0) {
  202                         DPRINTF(("%s: length mismatch (should be %d instead "
  203                                 "of %d)\n", __func__,
  204                                 m->m_pkthdr.len,
  205                                 m->m_pkthdr.len + m1->m_next->m_len));
  206 
  207                         m_freem(m);
  208                         return NULL;
  209                 }
  210 
  211                 m0 = m1->m_next;
  212         }
  213 
  214         if (pad > M_TRAILINGSPACE(m0)) {
  215                 /* Add an mbuf to the chain. */
  216                 MGET(m1, M_NOWAIT, MT_DATA);
  217                 if (m1 == NULL) {
  218                         m_freem(m0);
  219                         DPRINTF(("%s: unable to get extra mbuf\n", __func__));
  220                         return NULL;
  221                 }
  222 
  223                 m0->m_next = m1;
  224                 m0 = m1;
  225                 m0->m_len = 0;
  226         }
  227 
  228         retval = m0->m_data + m0->m_len;
  229         m0->m_len += pad;
  230         m->m_pkthdr.len += pad;
  231 
  232         return retval;
  233 }
  234 
  235 /*
  236  * Remove hlen data at offset skip in the packet.  This is used by
  237  * the protocols strip protocol headers and associated data (e.g. IV,
  238  * authenticator) on input.
  239  */
  240 int
  241 m_striphdr(struct mbuf *m, int skip, int hlen)
  242 {
  243         struct mbuf *m1;
  244         int roff;
  245 
  246         /* Find beginning of header */
  247         m1 = m_getptr(m, skip, &roff);
  248         if (m1 == NULL)
  249                 return (EINVAL);
  250 
  251         /* Remove the header and associated data from the mbuf. */
  252         if (roff == 0) {
  253                 /* The header was at the beginning of the mbuf */
  254                 IPSECSTAT_INC(ips_input_front);
  255                 m_adj(m1, hlen);
  256                 if (m1 != m)
  257                         m->m_pkthdr.len -= hlen;
  258         } else if (roff + hlen >= m1->m_len) {
  259                 struct mbuf *mo;
  260                 int adjlen;
  261 
  262                 /*
  263                  * Part or all of the header is at the end of this mbuf,
  264                  * so first let's remove the remainder of the header from
  265                  * the beginning of the remainder of the mbuf chain, if any.
  266                  */
  267                 IPSECSTAT_INC(ips_input_end);
  268                 if (roff + hlen > m1->m_len) {
  269                         adjlen = roff + hlen - m1->m_len;
  270 
  271                         /* Adjust the next mbuf by the remainder */
  272                         m_adj(m1->m_next, adjlen);
  273 
  274                         /* The second mbuf is guaranteed not to have a pkthdr... */
  275                         m->m_pkthdr.len -= adjlen;
  276                 }
  277 
  278                 /* Now, let's unlink the mbuf chain for a second...*/
  279                 mo = m1->m_next;
  280                 m1->m_next = NULL;
  281 
  282                 /* ...and trim the end of the first part of the chain...sick */
  283                 adjlen = m1->m_len - roff;
  284                 m_adj(m1, -adjlen);
  285                 if (m1 != m)
  286                         m->m_pkthdr.len -= adjlen;
  287 
  288                 /* Finally, let's relink */
  289                 m1->m_next = mo;
  290         } else {
  291                 /*
  292                  * The header lies in the "middle" of the mbuf; copy
  293                  * the remainder of the mbuf down over the header.
  294                  */
  295                 IPSECSTAT_INC(ips_input_middle);
  296                 bcopy(mtod(m1, u_char *) + roff + hlen,
  297                       mtod(m1, u_char *) + roff,
  298                       m1->m_len - (roff + hlen));
  299                 m1->m_len -= hlen;
  300                 m->m_pkthdr.len -= hlen;
  301         }
  302         return (0);
  303 }
  304 
  305 /*
  306  * Diagnostic routine to check mbuf alignment as required by the
  307  * crypto device drivers (that use DMA).
  308  */
  309 void
  310 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
  311 {
  312         int roff;
  313         struct mbuf *m = m_getptr(m0, off, &roff);
  314         caddr_t addr;
  315 
  316         if (m == NULL)
  317                 return;
  318         printf("%s (off %u len %u): ", where, off, len);
  319         addr = mtod(m, caddr_t) + roff;
  320         do {
  321                 int mlen;
  322 
  323                 if (((uintptr_t) addr) & 3) {
  324                         printf("addr misaligned %p,", addr);
  325                         break;
  326                 }
  327                 mlen = m->m_len;
  328                 if (mlen > len)
  329                         mlen = len;
  330                 len -= mlen;
  331                 if (len && (mlen & 3)) {
  332                         printf("len mismatch %u,", mlen);
  333                         break;
  334                 }
  335                 m = m->m_next;
  336                 addr = m ? mtod(m, caddr_t) : NULL;
  337         } while (m && len > 0);
  338         for (m = m0; m; m = m->m_next)
  339                 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
  340         printf("\n");
  341 }
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FreeBSD/Linux Kernel Cross Reference sys/netipsec/ipsec_mbuf.c

FreeBSD/Linux Kernel Cross Reference
sys/netipsec/ipsec_mbuf.c
