sys/kern/uipc_mbuf2.c

   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("$FreeBSD$");
  65
  66 /*#define PULLDOWN_DEBUG*/
  67
  68 #include "opt_mac.h"
  69
  70 #include <sys/param.h>
  71 #include <sys/systm.h>
  72 #include <sys/kernel.h>
  73 #include <sys/lock.h>
  74 #include <sys/malloc.h>
  75 #include <sys/mbuf.h>
  76 #include <sys/mutex.h>
  77
  78 #include <security/mac/mac_framework.h>
  79
  80 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME,
  81     "packet-attached information");
  82
  83 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
  84 static struct mbuf *m_dup1(struct mbuf *, int, int, int);
  85
  86 /*
  87  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
  88  * packet chain before "off" is kept untouched.
  89  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
  90  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
  91  *
  92  * on error return (NULL return value), original "m" will be freed.
  93  *
  94  * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
  95  */
  96 struct mbuf *
  97 m_pulldown(struct mbuf *m, int off, int len, int *offp)
  98 {
  99         struct mbuf *n, *o;
 100         int hlen, tlen, olen;
 101         int writable;
 102
 103         /* check invalid arguments. */
 104         if (m == NULL)
 105                 panic("m == NULL in m_pulldown()");
 106         if (len > MCLBYTES) {
 107                 m_freem(m);
 108                 return NULL;    /* impossible */
 109         }
 110
 111 #ifdef PULLDOWN_DEBUG
 112     {
 113         struct mbuf *t;
 114         printf("before:");
 115         for (t = m; t; t = t->m_next)
 116                 printf(" %d", t->m_len);
 117         printf("\n");
 118     }
 119 #endif
 120         n = m;
 121         while (n != NULL && off > 0) {
 122                 if (n->m_len > off)
 123                         break;
 124                 off -= n->m_len;
 125                 n = n->m_next;
 126         }
 127         /* be sure to point non-empty mbuf */
 128         while (n != NULL && n->m_len == 0)
 129                 n = n->m_next;
 130         if (!n) {
 131                 m_freem(m);
 132                 return NULL;    /* mbuf chain too short */
 133         }
 134
 135         /*
 136          * XXX: This code is flawed because it considers a "writable" mbuf
 137          *      data region to require all of the following:
 138          *        (i) mbuf _has_ to have M_EXT set; if it is just a regular
 139          *            mbuf, it is still not considered "writable."
 140          *        (ii) since mbuf has M_EXT, the ext_type _has_ to be
 141          *             EXT_CLUSTER. Anything else makes it non-writable.
 142          *        (iii) M_WRITABLE() must evaluate true.
 143          *      Ideally, the requirement should only be (iii).
 144          *
 145          * If we're writable, we're sure we're writable, because the ref. count
 146          * cannot increase from 1, as that would require posession of mbuf
 147          * n by someone else (which is impossible). However, if we're _not_
 148          * writable, we may eventually become writable )if the ref. count drops
 149          * to 1), but we'll fail to notice it unless we re-evaluate
 150          * M_WRITABLE(). For now, we only evaluate once at the beginning and
 151          * live with this.
 152          */
 153         /*
 154          * XXX: This is dumb. If we're just a regular mbuf with no M_EXT,
 155          *      then we're not "writable," according to this code.
 156          */
 157         writable = 0;
 158         if ((n->m_flags & M_EXT) == 0 ||
 159             (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
 160                 writable = 1;
 161
 162         /*
 163          * the target data is on <n, off>.
 164          * if we got enough data on the mbuf "n", we're done.
 165          */
 166         if ((off == 0 || offp) && len <= n->m_len - off && writable)
 167                 goto ok;
 168
 169         /*
 170          * when len <= n->m_len - off and off != 0, it is a special case.
 171          * len bytes from <n, off> sits in single mbuf, but the caller does
 172          * not like the starting position (off).
 173          * chop the current mbuf into two pieces, set off to 0.
 174          */
 175         if (len <= n->m_len - off) {
 176                 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
 177                 if (o == NULL) {
 178                         m_freem(m);
 179                         return NULL;    /* ENOBUFS */
 180                 }
 181                 n->m_len = off;
 182                 o->m_next = n->m_next;
 183                 n->m_next = o;
 184                 n = n->m_next;
 185                 off = 0;
 186                 goto ok;
 187         }
 188
 189         /*
 190          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
 191          * and construct contiguous mbuf with m_len == len.
 192          * note that hlen + tlen == len, and tlen > 0.
 193          */
 194         hlen = n->m_len - off;
 195         tlen = len - hlen;
 196
 197         /*
 198          * ensure that we have enough trailing data on mbuf chain.
 199          * if not, we can do nothing about the chain.
 200          */
 201         olen = 0;
 202         for (o = n->m_next; o != NULL; o = o->m_next)
 203                 olen += o->m_len;
 204         if (hlen + olen < len) {
 205                 m_freem(m);
 206                 return NULL;    /* mbuf chain too short */
 207         }
 208
 209         /*
 210          * easy cases first.
 211          * we need to use m_copydata() to get data from <n->m_next, 0>.
 212          */
 213         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
 214          && writable) {
 215                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
 216                 n->m_len += tlen;
 217                 m_adj(n->m_next, tlen);
 218                 goto ok;
 219         }
 220         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
 221          && writable) {
 222                 n->m_next->m_data -= hlen;
 223                 n->m_next->m_len += hlen;
 224                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
 225                 n->m_len -= hlen;
 226                 n = n->m_next;
 227                 off = 0;
 228                 goto ok;
 229         }
 230
 231         /*
 232          * now, we need to do the hard way.  don't m_copy as there's no room
 233          * on both end.
 234          */
 235         if (len > MLEN)
 236                 o = m_getcl(M_DONTWAIT, m->m_type, 0);
 237         else
 238                 o = m_get(M_DONTWAIT, m->m_type);
 239         if (!o) {
 240                 m_freem(m);
 241                 return NULL;    /* ENOBUFS */
 242         }
 243         /* get hlen from <n, off> into <o, 0> */
 244         o->m_len = hlen;
 245         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
 246         n->m_len -= hlen;
 247         /* get tlen from <n->m_next, 0> into <o, hlen> */
 248         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
 249         o->m_len += tlen;
 250         m_adj(n->m_next, tlen);
 251         o->m_next = n->m_next;
 252         n->m_next = o;
 253         n = o;
 254         off = 0;
 255
 256 ok:
 257 #ifdef PULLDOWN_DEBUG
 258     {
 259         struct mbuf *t;
 260         printf("after:");
 261         for (t = m; t; t = t->m_next)
 262                 printf("%c%d", t == n ? '*' : ' ', t->m_len);
 263         printf(" (off=%d)\n", off);
 264     }
 265 #endif
 266         if (offp)
 267                 *offp = off;
 268         return n;
 269 }
 270
 271 static struct mbuf *
 272 m_dup1(struct mbuf *m, int off, int len, int wait)
 273 {
 274         struct mbuf *n;
 275         int copyhdr;
 276
 277         if (len > MCLBYTES)
 278                 return NULL;
 279         if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
 280                 copyhdr = 1;
 281         else
 282                 copyhdr = 0;
 283         if (len >= MINCLSIZE) {
 284                 if (copyhdr == 1)
 285                         n = m_getcl(wait, m->m_type, M_PKTHDR);
 286                 else
 287                         n = m_getcl(wait, m->m_type, 0);
 288         } else {
 289                 if (copyhdr == 1)
 290                         n = m_gethdr(wait, m->m_type);
 291                 else
 292                         n = m_get(wait, m->m_type);
 293         }
 294         if (!n)
 295                 return NULL; /* ENOBUFS */
 296
 297         if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
 298                 m_free(n);
 299                 return NULL;
 300         }
 301         m_copydata(m, off, len, mtod(n, caddr_t));
 302         n->m_len = len;
 303         return n;
 304 }
 305
 306 /* Free a packet tag. */
 307 void
 308 m_tag_free_default(struct m_tag *t)
 309 {
 310 #ifdef MAC
 311         if (t->m_tag_id == PACKET_TAG_MACLABEL)
 312                 mac_mbuf_tag_destroy(t);
 313 #endif
 314         free(t, M_PACKET_TAGS);
 315 }
 316
 317 /* Get a packet tag structure along with specified data following. */
 318 struct m_tag *
 319 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
 320 {
 321         struct m_tag *t;
 322
 323         MBUF_CHECKSLEEP(wait);
 324         if (len < 0)
 325                 return NULL;
 326         t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
 327         if (t == NULL)
 328                 return NULL;
 329         m_tag_setup(t, cookie, type, len);
 330         t->m_tag_free = m_tag_free_default;
 331         return t;
 332 }
 333
 334 /* Unlink and free a packet tag. */
 335 void
 336 m_tag_delete(struct mbuf *m, struct m_tag *t)
 337 {
 338
 339         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
 340         m_tag_unlink(m, t);
 341         m_tag_free(t);
 342 }
 343
 344 /* Unlink and free a packet tag chain, starting from given tag. */
 345 void
 346 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
 347 {
 348         struct m_tag *p, *q;
 349
 350         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
 351         if (t != NULL)
 352                 p = t;
 353         else
 354                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 355         if (p == NULL)
 356                 return;
 357         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
 358                 m_tag_delete(m, q);
 359         m_tag_delete(m, p);
 360 }
 361
 362 /*
 363  * Strip off all tags that would normally vanish when
 364  * passing through a network interface.  Only persistent
 365  * tags will exist after this; these are expected to remain
 366  * so long as the mbuf chain exists, regardless of the
 367  * path the mbufs take.
 368  */
 369 void
 370 m_tag_delete_nonpersistent(struct mbuf *m)
 371 {
 372         struct m_tag *p, *q;
 373
 374         SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
 375                 if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
 376                         m_tag_delete(m, p);
 377 }
 378
 379 /* Find a tag, starting from a given position. */
 380 struct m_tag *
 381 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
 382 {
 383         struct m_tag *p;
 384
 385         KASSERT(m, ("m_tag_locate: null mbuf"));
 386         if (t == NULL)
 387                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 388         else
 389                 p = SLIST_NEXT(t, m_tag_link);
 390         while (p != NULL) {
 391                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
 392                         return p;
 393                 p = SLIST_NEXT(p, m_tag_link);
 394         }
 395         return NULL;
 396 }
 397
 398 /* Copy a single tag. */
 399 struct m_tag *
 400 m_tag_copy(struct m_tag *t, int how)
 401 {
 402         struct m_tag *p;
 403
 404         MBUF_CHECKSLEEP(how);
 405         KASSERT(t, ("m_tag_copy: null tag"));
 406         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
 407         if (p == NULL)
 408                 return (NULL);
 409 #ifdef MAC
 410         /*
 411          * XXXMAC: we should probably pass off the initialization, and
 412          * copying here?  can we hide that PACKET_TAG_MACLABEL is
 413          * special from the mbuf code?
 414          */
 415         if (t->m_tag_id == PACKET_TAG_MACLABEL) {
 416                 if (mac_mbuf_tag_init(p, how) != 0) {
 417                         m_tag_free(p);
 418                         return (NULL);
 419                 }
 420                 mac_mbuf_tag_copy(t, p);
 421         } else
 422 #endif
 423                 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
 424         return p;
 425 }
 426
 427 /*
 428  * Copy two tag chains. The destination mbuf (to) loses any attached
 429  * tags even if the operation fails. This should not be a problem, as
 430  * m_tag_copy_chain() is typically called with a newly-allocated
 431  * destination mbuf.
 432  */
 433 int
 434 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
 435 {
 436         struct m_tag *p, *t, *tprev = NULL;
 437
 438         MBUF_CHECKSLEEP(how);
 439         KASSERT(to && from,
 440                 ("m_tag_copy_chain: null argument, to %p from %p", to, from));
 441         m_tag_delete_chain(to, NULL);
 442         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
 443                 t = m_tag_copy(p, how);
 444                 if (t == NULL) {
 445                         m_tag_delete_chain(to, NULL);
 446                         return 0;
 447                 }
 448                 if (tprev == NULL)
 449                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
 450                 else
 451                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
 452                 tprev = t;
 453         }
 454         return 1;
 455 }