The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

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

Version: -  FREEBSD  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-2  -  FREEBSD-11-1  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-4  -  FREEBSD-10-3  -  FREEBSD-10-2  -  FREEBSD-10-1  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-3  -  FREEBSD-9-2  -  FREEBSD-9-1  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-4  -  FREEBSD-8-3  -  FREEBSD-8-2  -  FREEBSD-8-1  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-4  -  FREEBSD-7-3  -  FREEBSD-7-2  -  FREEBSD-7-1  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-4  -  FREEBSD-6-3  -  FREEBSD-6-2  -  FREEBSD-6-1  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-5  -  FREEBSD-5-4  -  FREEBSD-5-3  -  FREEBSD-5-2  -  FREEBSD-5-1  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  linux-2.6  -  linux-2.4.22  -  MK83  -  MK84  -  PLAN9  -  DFBSD  -  NETBSD  -  NETBSD5  -  NETBSD4  -  NETBSD3  -  NETBSD20  -  OPENBSD  -  xnu-517  -  xnu-792  -  xnu-792.6.70  -  xnu-1228  -  xnu-1456.1.26  -  xnu-1699.24.8  -  xnu-2050.18.24  -  OPENSOLARIS  -  minix-3-1-1 
SearchContext: -  none  -  3  -  10 

    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  * 4. Neither the name of the University nor the names of its contributors
   45  *    may be used to endorse or promote products derived from this software
   46  *    without specific prior written permission.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
   61  */
   62 
   63 #include <sys/cdefs.h>
   64 __FBSDID("$FreeBSD: releng/10.1/sys/kern/uipc_mbuf2.c 243882 2012-12-05 08:04:20Z glebius $");
   65 
   66 /*#define PULLDOWN_DEBUG*/
   67 
   68 #include <sys/param.h>
   69 #include <sys/systm.h>
   70 #include <sys/kernel.h>
   71 #include <sys/lock.h>
   72 #include <sys/malloc.h>
   73 #include <sys/mbuf.h>
   74 #include <sys/mutex.h>
   75 
   76 #include <security/mac/mac_framework.h>
   77 
   78 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME,
   79     "packet-attached information");
   80 
   81 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
   82 static struct mbuf *m_dup1(struct mbuf *, int, int, int);
   83 
   84 /*
   85  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
   86  * packet chain before "off" is kept untouched.
   87  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
   88  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
   89  *
   90  * on error return (NULL return value), original "m" will be freed.
   91  *
   92  * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
   93  */
   94 struct mbuf *
   95 m_pulldown(struct mbuf *m, int off, int len, int *offp)
   96 {
   97         struct mbuf *n, *o;
   98         int hlen, tlen, olen;
   99         int writable;
  100 
  101         /* check invalid arguments. */
  102         if (m == NULL)
  103                 panic("m == NULL in m_pulldown()");
  104         if (len > MCLBYTES) {
  105                 m_freem(m);
  106                 return NULL;    /* impossible */
  107         }
  108 
  109 #ifdef PULLDOWN_DEBUG
  110     {
  111         struct mbuf *t;
  112         printf("before:");
  113         for (t = m; t; t = t->m_next)
  114                 printf(" %d", t->m_len);
  115         printf("\n");
  116     }
  117 #endif
  118         n = m;
  119         while (n != NULL && off > 0) {
  120                 if (n->m_len > off)
  121                         break;
  122                 off -= n->m_len;
  123                 n = n->m_next;
  124         }
  125         /* be sure to point non-empty mbuf */
  126         while (n != NULL && n->m_len == 0)
  127                 n = n->m_next;
  128         if (!n) {
  129                 m_freem(m);
  130                 return NULL;    /* mbuf chain too short */
  131         }
  132 
  133         /*
  134          * XXX: This code is flawed because it considers a "writable" mbuf
  135          *      data region to require all of the following:
  136          *        (i) mbuf _has_ to have M_EXT set; if it is just a regular
  137          *            mbuf, it is still not considered "writable."
  138          *        (ii) since mbuf has M_EXT, the ext_type _has_ to be
  139          *             EXT_CLUSTER. Anything else makes it non-writable.
  140          *        (iii) M_WRITABLE() must evaluate true.
  141          *      Ideally, the requirement should only be (iii).
  142          *
  143          * If we're writable, we're sure we're writable, because the ref. count
  144          * cannot increase from 1, as that would require posession of mbuf
  145          * n by someone else (which is impossible). However, if we're _not_
  146          * writable, we may eventually become writable )if the ref. count drops
  147          * to 1), but we'll fail to notice it unless we re-evaluate
  148          * M_WRITABLE(). For now, we only evaluate once at the beginning and
  149          * live with this.
  150          */
  151         /*
  152          * XXX: This is dumb. If we're just a regular mbuf with no M_EXT,
  153          *      then we're not "writable," according to this code.
  154          */
  155         writable = 0;
  156         if ((n->m_flags & M_EXT) == 0 ||
  157             (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
  158                 writable = 1;
  159 
  160         /*
  161          * the target data is on <n, off>.
  162          * if we got enough data on the mbuf "n", we're done.
  163          */
  164         if ((off == 0 || offp) && len <= n->m_len - off && writable)
  165                 goto ok;
  166 
  167         /*
  168          * when len <= n->m_len - off and off != 0, it is a special case.
  169          * len bytes from <n, off> sits in single mbuf, but the caller does
  170          * not like the starting position (off).
  171          * chop the current mbuf into two pieces, set off to 0.
  172          */
  173         if (len <= n->m_len - off) {
  174                 o = m_dup1(n, off, n->m_len - off, M_NOWAIT);
  175                 if (o == NULL) {
  176                         m_freem(m);
  177                         return NULL;    /* ENOBUFS */
  178                 }
  179                 n->m_len = off;
  180                 o->m_next = n->m_next;
  181                 n->m_next = o;
  182                 n = n->m_next;
  183                 off = 0;
  184                 goto ok;
  185         }
  186 
  187         /*
  188          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
  189          * and construct contiguous mbuf with m_len == len.
  190          * note that hlen + tlen == len, and tlen > 0.
  191          */
  192         hlen = n->m_len - off;
  193         tlen = len - hlen;
  194 
  195         /*
  196          * ensure that we have enough trailing data on mbuf chain.
  197          * if not, we can do nothing about the chain.
  198          */
  199         olen = 0;
  200         for (o = n->m_next; o != NULL; o = o->m_next)
  201                 olen += o->m_len;
  202         if (hlen + olen < len) {
  203                 m_freem(m);
  204                 return NULL;    /* mbuf chain too short */
  205         }
  206 
  207         /*
  208          * easy cases first.
  209          * we need to use m_copydata() to get data from <n->m_next, 0>.
  210          */
  211         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
  212          && writable) {
  213                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
  214                 n->m_len += tlen;
  215                 m_adj(n->m_next, tlen);
  216                 goto ok;
  217         }
  218         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
  219          && writable) {
  220                 n->m_next->m_data -= hlen;
  221                 n->m_next->m_len += hlen;
  222                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
  223                 n->m_len -= hlen;
  224                 n = n->m_next;
  225                 off = 0;
  226                 goto ok;
  227         }
  228 
  229         /*
  230          * now, we need to do the hard way.  don't m_copy as there's no room
  231          * on both end.
  232          */
  233         if (len > MLEN)
  234                 o = m_getcl(M_NOWAIT, m->m_type, 0);
  235         else
  236                 o = m_get(M_NOWAIT, m->m_type);
  237         if (!o) {
  238                 m_freem(m);
  239                 return NULL;    /* ENOBUFS */
  240         }
  241         /* get hlen from <n, off> into <o, 0> */
  242         o->m_len = hlen;
  243         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
  244         n->m_len -= hlen;
  245         /* get tlen from <n->m_next, 0> into <o, hlen> */
  246         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
  247         o->m_len += tlen;
  248         m_adj(n->m_next, tlen);
  249         o->m_next = n->m_next;
  250         n->m_next = o;
  251         n = o;
  252         off = 0;
  253 
  254 ok:
  255 #ifdef PULLDOWN_DEBUG
  256     {
  257         struct mbuf *t;
  258         printf("after:");
  259         for (t = m; t; t = t->m_next)
  260                 printf("%c%d", t == n ? '*' : ' ', t->m_len);
  261         printf(" (off=%d)\n", off);
  262     }
  263 #endif
  264         if (offp)
  265                 *offp = off;
  266         return n;
  267 }
  268 
  269 static struct mbuf *
  270 m_dup1(struct mbuf *m, int off, int len, int wait)
  271 {
  272         struct mbuf *n;
  273         int copyhdr;
  274 
  275         if (len > MCLBYTES)
  276                 return NULL;
  277         if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
  278                 copyhdr = 1;
  279         else
  280                 copyhdr = 0;
  281         if (len >= MINCLSIZE) {
  282                 if (copyhdr == 1)
  283                         n = m_getcl(wait, m->m_type, M_PKTHDR);
  284                 else
  285                         n = m_getcl(wait, m->m_type, 0);
  286         } else {
  287                 if (copyhdr == 1)
  288                         n = m_gethdr(wait, m->m_type);
  289                 else
  290                         n = m_get(wait, m->m_type);
  291         }
  292         if (!n)
  293                 return NULL; /* ENOBUFS */
  294 
  295         if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
  296                 m_free(n);
  297                 return NULL;
  298         }
  299         m_copydata(m, off, len, mtod(n, caddr_t));
  300         n->m_len = len;
  301         return n;
  302 }
  303 
  304 /* Free a packet tag. */
  305 void
  306 m_tag_free_default(struct m_tag *t)
  307 {
  308 #ifdef MAC
  309         if (t->m_tag_id == PACKET_TAG_MACLABEL)
  310                 mac_mbuf_tag_destroy(t);
  311 #endif
  312         free(t, M_PACKET_TAGS);
  313 }
  314 
  315 /* Get a packet tag structure along with specified data following. */
  316 struct m_tag *
  317 m_tag_alloc(uint32_t cookie, int type, int len, int wait)
  318 {
  319         struct m_tag *t;
  320 
  321         MBUF_CHECKSLEEP(wait);
  322         if (len < 0)
  323                 return NULL;
  324         t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
  325         if (t == NULL)
  326                 return NULL;
  327         m_tag_setup(t, cookie, type, len);
  328         t->m_tag_free = m_tag_free_default;
  329         return t;
  330 }
  331 
  332 /* Unlink and free a packet tag. */
  333 void
  334 m_tag_delete(struct mbuf *m, struct m_tag *t)
  335 {
  336 
  337         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
  338         m_tag_unlink(m, t);
  339         m_tag_free(t);
  340 }
  341 
  342 /* Unlink and free a packet tag chain, starting from given tag. */
  343 void
  344 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
  345 {
  346         struct m_tag *p, *q;
  347 
  348         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
  349         if (t != NULL)
  350                 p = t;
  351         else
  352                 p = SLIST_FIRST(&m->m_pkthdr.tags);
  353         if (p == NULL)
  354                 return;
  355         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
  356                 m_tag_delete(m, q);
  357         m_tag_delete(m, p);
  358 }
  359 
  360 /*
  361  * Strip off all tags that would normally vanish when
  362  * passing through a network interface.  Only persistent
  363  * tags will exist after this; these are expected to remain
  364  * so long as the mbuf chain exists, regardless of the
  365  * path the mbufs take.
  366  */
  367 void
  368 m_tag_delete_nonpersistent(struct mbuf *m)
  369 {
  370         struct m_tag *p, *q;
  371 
  372         SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
  373                 if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
  374                         m_tag_delete(m, p);
  375 }
  376 
  377 /* Find a tag, starting from a given position. */
  378 struct m_tag *
  379 m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t)
  380 {
  381         struct m_tag *p;
  382 
  383         KASSERT(m, ("m_tag_locate: null mbuf"));
  384         if (t == NULL)
  385                 p = SLIST_FIRST(&m->m_pkthdr.tags);
  386         else
  387                 p = SLIST_NEXT(t, m_tag_link);
  388         while (p != NULL) {
  389                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
  390                         return p;
  391                 p = SLIST_NEXT(p, m_tag_link);
  392         }
  393         return NULL;
  394 }
  395 
  396 /* Copy a single tag. */
  397 struct m_tag *
  398 m_tag_copy(struct m_tag *t, int how)
  399 {
  400         struct m_tag *p;
  401 
  402         MBUF_CHECKSLEEP(how);
  403         KASSERT(t, ("m_tag_copy: null tag"));
  404         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
  405         if (p == NULL)
  406                 return (NULL);
  407 #ifdef MAC
  408         /*
  409          * XXXMAC: we should probably pass off the initialization, and
  410          * copying here?  can we hide that PACKET_TAG_MACLABEL is
  411          * special from the mbuf code?
  412          */
  413         if (t->m_tag_id == PACKET_TAG_MACLABEL) {
  414                 if (mac_mbuf_tag_init(p, how) != 0) {
  415                         m_tag_free(p);
  416                         return (NULL);
  417                 }
  418                 mac_mbuf_tag_copy(t, p);
  419         } else
  420 #endif
  421                 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
  422         return p;
  423 }
  424 
  425 /*
  426  * Copy two tag chains. The destination mbuf (to) loses any attached
  427  * tags even if the operation fails. This should not be a problem, as
  428  * m_tag_copy_chain() is typically called with a newly-allocated
  429  * destination mbuf.
  430  */
  431 int
  432 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
  433 {
  434         struct m_tag *p, *t, *tprev = NULL;
  435 
  436         MBUF_CHECKSLEEP(how);
  437         KASSERT(to && from,
  438                 ("m_tag_copy_chain: null argument, to %p from %p", to, from));
  439         m_tag_delete_chain(to, NULL);
  440         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
  441                 t = m_tag_copy(p, how);
  442                 if (t == NULL) {
  443                         m_tag_delete_chain(to, NULL);
  444                         return 0;
  445                 }
  446                 if (tprev == NULL)
  447                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
  448                 else
  449                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
  450                 tprev = t;
  451         }
  452         return 1;
  453 }

Cache object: 883d439b4320d140c9a7adf47d31d43a


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.