uipc_mbuf2.c

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    1 /*      $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $     */
    2 /*      $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $   */
    3 
    4 /*
    5  * Copyright (C) 1999 WIDE Project.
    6  * All rights reserved.
    7  * 
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  * 
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 /*
   33  * Copyright (c) 1982, 1986, 1988, 1991, 1993
   34  *      The Regents of the University of California.  All rights reserved.
   35  *
   36  * Redistribution and use in source and binary forms, with or without
   37  * modification, are permitted provided that the following conditions
   38  * are met:
   39  * 1. Redistributions of source code must retain the above copyright
   40  *    notice, this list of conditions and the following disclaimer.
   41  * 2. Redistributions in binary form must reproduce the above copyright
   42  *    notice, this list of conditions and the following disclaimer in the
   43  *    documentation and/or other materials provided with the distribution.
   44  * 3. All advertising materials mentioning features or use of this software
   45  *    must display the following acknowledgement:
   46  *      This product includes software developed by the University of
   47  *      California, Berkeley and its contributors.
   48  * 4. Neither the name of the University nor the names of its contributors
   49  *    may be used to endorse or promote products derived from this software
   50  *    without specific prior written permission.
   51  *
   52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   62  * SUCH DAMAGE.
   63  *
   64  *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
   65  */
   66 
   67 #include <sys/cdefs.h>
   68 __FBSDID("$FreeBSD: releng/5.2/sys/kern/uipc_mbuf2.c 121645 2003-10-29 05:40:07Z sam $");
   69 
   70 /*#define PULLDOWN_DEBUG*/
   71 
   72 #include "opt_mac.h"
   73 
   74 #include <sys/param.h>
   75 #include <sys/systm.h>
   76 #include <sys/kernel.h>
   77 #include <sys/lock.h>
   78 #include <sys/mac.h>
   79 #include <sys/malloc.h>
   80 #include <sys/mbuf.h>
   81 #include <sys/mutex.h>
   82 
   83 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information");
   84 
   85 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
   86 static struct mbuf *m_dup1(struct mbuf *, int, int, int);
   87 
   88 /*
   89  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
   90  * packet chain before "off" is kept untouched.
   91  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
   92  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
   93  *
   94  * on error return (NULL return value), original "m" will be freed.
   95  *
   96  * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
   97  */
   98 struct mbuf *
   99 m_pulldown(struct mbuf *m, int off, int len, int *offp)
  100 {
  101         struct mbuf *n, *o;
  102         int hlen, tlen, olen;
  103         int writable;
  104 
  105         /* check invalid arguments. */
  106         if (m == NULL)
  107                 panic("m == NULL in m_pulldown()");
  108         if (len > MCLBYTES) {
  109                 m_freem(m);
  110                 return NULL;    /* impossible */
  111         }
  112 
  113 #ifdef PULLDOWN_DEBUG
  114     {
  115         struct mbuf *t;
  116         printf("before:");
  117         for (t = m; t; t = t->m_next)
  118                 printf(" %d", t->m_len);
  119         printf("\n");
  120     }
  121 #endif
  122         n = m;
  123         while (n != NULL && off > 0) {
  124                 if (n->m_len > off)
  125                         break;
  126                 off -= n->m_len;
  127                 n = n->m_next;
  128         }
  129         /* be sure to point non-empty mbuf */
  130         while (n != NULL && n->m_len == 0)
  131                 n = n->m_next;
  132         if (!n) {
  133                 m_freem(m);
  134                 return NULL;    /* mbuf chain too short */
  135         }
  136 
  137         /*
  138          * XXX: This code is flawed because it considers a "writable" mbuf
  139          *      data region to require all of the following:
  140          *        (i) mbuf _has_ to have M_EXT set; if it is just a regular
  141          *            mbuf, it is still not considered "writable."
  142          *        (ii) since mbuf has M_EXT, the ext_type _has_ to be
  143          *             EXT_CLUSTER. Anything else makes it non-writable.
  144          *        (iii) M_WRITABLE() must evaluate true.
  145          *      Ideally, the requirement should only be (iii).
  146          *
  147          * If we're writable, we're sure we're writable, because the ref. count
  148          * cannot increase from 1, as that would require posession of mbuf
  149          * n by someone else (which is impossible). However, if we're _not_
  150          * writable, we may eventually become writable )if the ref. count drops
  151          * to 1), but we'll fail to notice it unless we re-evaluate
  152          * M_WRITABLE(). For now, we only evaluate once at the beginning and
  153          * live with this.
  154          */
  155         /*
  156          * XXX: This is dumb. If we're just a regular mbuf with no M_EXT,
  157          *      then we're not "writable," according to this code.
  158          */
  159         writable = 0;
  160         if ((n->m_flags & M_EXT) == 0 ||
  161             (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
  162                 writable = 1;
  163 
  164         /*
  165          * the target data is on <n, off>.
  166          * if we got enough data on the mbuf "n", we're done.
  167          */
  168         if ((off == 0 || offp) && len <= n->m_len - off && writable)
  169                 goto ok;
  170 
  171         /*
  172          * when len <= n->m_len - off and off != 0, it is a special case.
  173          * len bytes from <n, off> sits in single mbuf, but the caller does
  174          * not like the starting position (off).
  175          * chop the current mbuf into two pieces, set off to 0.
  176          */
  177         if (len <= n->m_len - off) {
  178                 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
  179                 if (o == NULL) {
  180                         m_freem(m);
  181                         return NULL;    /* ENOBUFS */
  182                 }
  183                 n->m_len = off;
  184                 o->m_next = n->m_next;
  185                 n->m_next = o;
  186                 n = n->m_next;
  187                 off = 0;
  188                 goto ok;
  189         }
  190 
  191         /*
  192          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
  193          * and construct contiguous mbuf with m_len == len.
  194          * note that hlen + tlen == len, and tlen > 0.
  195          */
  196         hlen = n->m_len - off;
  197         tlen = len - hlen;
  198 
  199         /*
  200          * ensure that we have enough trailing data on mbuf chain.
  201          * if not, we can do nothing about the chain.
  202          */
  203         olen = 0;
  204         for (o = n->m_next; o != NULL; o = o->m_next)
  205                 olen += o->m_len;
  206         if (hlen + olen < len) {
  207                 m_freem(m);
  208                 return NULL;    /* mbuf chain too short */
  209         }
  210 
  211         /*
  212          * easy cases first.
  213          * we need to use m_copydata() to get data from <n->m_next, 0>.
  214          */
  215         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
  216          && writable) {
  217                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
  218                 n->m_len += tlen;
  219                 m_adj(n->m_next, tlen);
  220                 goto ok;
  221         }
  222         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
  223          && writable) {
  224                 n->m_next->m_data -= hlen;
  225                 n->m_next->m_len += hlen;
  226                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
  227                 n->m_len -= hlen;
  228                 n = n->m_next;
  229                 off = 0;
  230                 goto ok;
  231         }
  232 
  233         /*
  234          * now, we need to do the hard way.  don't m_copy as there's no room
  235          * on both end.
  236          */
  237         MGET(o, M_DONTWAIT, m->m_type);
  238         if (o && len > MLEN) {
  239                 MCLGET(o, M_DONTWAIT);
  240                 if ((o->m_flags & M_EXT) == 0) {
  241                         m_free(o);
  242                         o = NULL;
  243                 }
  244         }
  245         if (!o) {
  246                 m_freem(m);
  247                 return NULL;    /* ENOBUFS */
  248         }
  249         /* get hlen from <n, off> into <o, 0> */
  250         o->m_len = hlen;
  251         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
  252         n->m_len -= hlen;
  253         /* get tlen from <n->m_next, 0> into <o, hlen> */
  254         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
  255         o->m_len += tlen;
  256         m_adj(n->m_next, tlen);
  257         o->m_next = n->m_next;
  258         n->m_next = o;
  259         n = o;
  260         off = 0;
  261 
  262 ok:
  263 #ifdef PULLDOWN_DEBUG
  264     {
  265         struct mbuf *t;
  266         printf("after:");
  267         for (t = m; t; t = t->m_next)
  268                 printf("%c%d", t == n ? '*' : ' ', t->m_len);
  269         printf(" (off=%d)\n", off);
  270     }
  271 #endif
  272         if (offp)
  273                 *offp = off;
  274         return n;
  275 }
  276 
  277 static struct mbuf *
  278 m_dup1(struct mbuf *m, int off, int len, int wait)
  279 {
  280         struct mbuf *n;
  281         int l;
  282         int copyhdr;
  283 
  284         if (len > MCLBYTES)
  285                 return NULL;
  286         if (off == 0 && (m->m_flags & M_PKTHDR) != 0) {
  287                 copyhdr = 1;
  288                 MGETHDR(n, wait, m->m_type);
  289                 l = MHLEN;
  290         } else {
  291                 copyhdr = 0;
  292                 MGET(n, wait, m->m_type);
  293                 l = MLEN;
  294         }
  295         if (n && len > l) {
  296                 MCLGET(n, wait);
  297                 if ((n->m_flags & M_EXT) == 0) {
  298                         m_free(n);
  299                         n = NULL;
  300                 }
  301         }
  302         if (!n)
  303                 return NULL;
  304 
  305         if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
  306                 m_free(n);
  307                 return NULL;
  308         }
  309         m_copydata(m, off, len, mtod(n, caddr_t));
  310         return n;
  311 }
  312 
  313 /* Get a packet tag structure along with specified data following. */
  314 struct m_tag *
  315 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
  316 {
  317         struct m_tag *t;
  318 
  319         if (len < 0)
  320                 return NULL;
  321         t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
  322         if (t == NULL)
  323                 return NULL;
  324         t->m_tag_id = type;
  325         t->m_tag_len = len;
  326         t->m_tag_cookie = cookie;
  327         return t;
  328 }
  329 
  330 /* Free a packet tag. */
  331 void
  332 m_tag_free(struct m_tag *t)
  333 {
  334 #ifdef MAC
  335         if (t->m_tag_id == PACKET_TAG_MACLABEL)
  336                 mac_destroy_mbuf_tag(t);
  337 #endif
  338         free(t, M_PACKET_TAGS);
  339 }
  340 
  341 /* Prepend a packet tag. */
  342 void
  343 m_tag_prepend(struct mbuf *m, struct m_tag *t)
  344 {
  345         KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
  346         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
  347 }
  348 
  349 /* Unlink a packet tag. */
  350 void
  351 m_tag_unlink(struct mbuf *m, struct m_tag *t)
  352 {
  353         KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
  354         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
  355 }
  356 
  357 /* Unlink and free a packet tag. */
  358 void
  359 m_tag_delete(struct mbuf *m, struct m_tag *t)
  360 {
  361         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
  362         m_tag_unlink(m, t);
  363         m_tag_free(t);
  364 }
  365 
  366 /* Unlink and free a packet tag chain, starting from given tag. */
  367 void
  368 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
  369 {
  370         struct m_tag *p, *q;
  371 
  372         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
  373         if (t != NULL)
  374                 p = t;
  375         else
  376                 p = SLIST_FIRST(&m->m_pkthdr.tags);
  377         if (p == NULL)
  378                 return;
  379         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
  380                 m_tag_delete(m, q);
  381         m_tag_delete(m, p);
  382 }
  383 
  384 /*
  385  * Strip off all tags that would normally vanish when
  386  * passing through a network interface.  Only persistent
  387  * tags will exist after this; these are expected to remain
  388  * so long as the mbuf chain exists, regardless of the
  389  * path the mbufs take.
  390  */
  391 void
  392 m_tag_delete_nonpersistent(struct mbuf *m)
  393 {
  394         struct m_tag *p, *q;
  395 
  396         SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
  397                 if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
  398                         m_tag_delete(m, p);
  399 }
  400 
  401 /* Find a tag, starting from a given position. */
  402 struct m_tag *
  403 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
  404 {
  405         struct m_tag *p;
  406 
  407         KASSERT(m, ("m_tag_locate: null mbuf"));
  408         if (t == NULL)
  409                 p = SLIST_FIRST(&m->m_pkthdr.tags);
  410         else
  411                 p = SLIST_NEXT(t, m_tag_link);
  412         while (p != NULL) {
  413                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
  414                         return p;
  415                 p = SLIST_NEXT(p, m_tag_link);
  416         }
  417         return NULL;
  418 }
  419 
  420 /* Copy a single tag. */
  421 struct m_tag *
  422 m_tag_copy(struct m_tag *t, int how)
  423 {
  424         struct m_tag *p;
  425 
  426         KASSERT(t, ("m_tag_copy: null tag"));
  427         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
  428         if (p == NULL)
  429                 return (NULL);
  430 #ifdef MAC
  431         /*
  432          * XXXMAC: we should probably pass off the initialization, and
  433          * copying here?  can we hide that PACKET_TAG_MACLABEL is
  434          * special from the mbuf code?
  435          */
  436         if (t->m_tag_id == PACKET_TAG_MACLABEL) {
  437                 if (mac_init_mbuf_tag(p, how) != 0) {
  438                         m_tag_free(p);
  439                         return (NULL);
  440                 }
  441                 mac_copy_mbuf_tag(t, p);
  442         } else
  443 #endif
  444                 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
  445         return p;
  446 }
  447 
  448 /*
  449  * Copy two tag chains. The destination mbuf (to) loses any attached
  450  * tags even if the operation fails. This should not be a problem, as
  451  * m_tag_copy_chain() is typically called with a newly-allocated
  452  * destination mbuf.
  453  */
  454 int
  455 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
  456 {
  457         struct m_tag *p, *t, *tprev = NULL;
  458 
  459         KASSERT(to && from,
  460                 ("m_tag_copy_chain: null argument, to %p from %p", to, from));
  461         m_tag_delete_chain(to, NULL);
  462         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
  463                 t = m_tag_copy(p, how);
  464                 if (t == NULL) {
  465                         m_tag_delete_chain(to, NULL);
  466                         return 0;
  467                 }
  468                 if (tprev == NULL)
  469                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
  470                 else
  471                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
  472                 tprev = t;
  473         }
  474         return 1;
  475 }
  476 
  477 /* Initialize tags on an mbuf. */
  478 void
  479 m_tag_init(struct mbuf *m)
  480 {
  481         SLIST_INIT(&m->m_pkthdr.tags);
  482 }
  483 
  484 /* Get first tag in chain. */
  485 struct m_tag *
  486 m_tag_first(struct mbuf *m)
  487 {
  488         return SLIST_FIRST(&m->m_pkthdr.tags);
  489 }
  490 
  491 /* Get next tag in chain. */
  492 struct m_tag *
  493 m_tag_next(struct mbuf *m, struct m_tag *t)
  494 {
  495         return SLIST_NEXT(t, m_tag_link);
  496 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/uipc_mbuf2.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf2.c
