FreeBSD/Linux Kernel Cross Reference
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: releng/6.0/sys/kern/uipc_mbuf2.c 148370 2005-07-25 00:08:12Z rwatson $");
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/mac.h>
75 #include <sys/malloc.h>
76 #include <sys/mbuf.h>
77 #include <sys/mutex.h>
78
79 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME,
80 "packet-attached information");
81
82 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
83 static struct mbuf *m_dup1(struct mbuf *, int, int, int);
84
85 /*
86 * ensure that [off, off + len) is contiguous on the mbuf chain "m".
87 * packet chain before "off" is kept untouched.
88 * if offp == NULL, the target will start at <retval, 0> on resulting chain.
89 * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
90 *
91 * on error return (NULL return value), original "m" will be freed.
92 *
93 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
94 */
95 struct mbuf *
96 m_pulldown(struct mbuf *m, int off, int len, int *offp)
97 {
98 struct mbuf *n, *o;
99 int hlen, tlen, olen;
100 int writable;
101
102 /* check invalid arguments. */
103 if (m == NULL)
104 panic("m == NULL in m_pulldown()");
105 if (len > MCLBYTES) {
106 m_freem(m);
107 return NULL; /* impossible */
108 }
109
110 #ifdef PULLDOWN_DEBUG
111 {
112 struct mbuf *t;
113 printf("before:");
114 for (t = m; t; t = t->m_next)
115 printf(" %d", t->m_len);
116 printf("\n");
117 }
118 #endif
119 n = m;
120 while (n != NULL && off > 0) {
121 if (n->m_len > off)
122 break;
123 off -= n->m_len;
124 n = n->m_next;
125 }
126 /* be sure to point non-empty mbuf */
127 while (n != NULL && n->m_len == 0)
128 n = n->m_next;
129 if (!n) {
130 m_freem(m);
131 return NULL; /* mbuf chain too short */
132 }
133
134 /*
135 * XXX: This code is flawed because it considers a "writable" mbuf
136 * data region to require all of the following:
137 * (i) mbuf _has_ to have M_EXT set; if it is just a regular
138 * mbuf, it is still not considered "writable."
139 * (ii) since mbuf has M_EXT, the ext_type _has_ to be
140 * EXT_CLUSTER. Anything else makes it non-writable.
141 * (iii) M_WRITABLE() must evaluate true.
142 * Ideally, the requirement should only be (iii).
143 *
144 * If we're writable, we're sure we're writable, because the ref. count
145 * cannot increase from 1, as that would require posession of mbuf
146 * n by someone else (which is impossible). However, if we're _not_
147 * writable, we may eventually become writable )if the ref. count drops
148 * to 1), but we'll fail to notice it unless we re-evaluate
149 * M_WRITABLE(). For now, we only evaluate once at the beginning and
150 * live with this.
151 */
152 /*
153 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT,
154 * then we're not "writable," according to this code.
155 */
156 writable = 0;
157 if ((n->m_flags & M_EXT) == 0 ||
158 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
159 writable = 1;
160
161 /*
162 * the target data is on <n, off>.
163 * if we got enough data on the mbuf "n", we're done.
164 */
165 if ((off == 0 || offp) && len <= n->m_len - off && writable)
166 goto ok;
167
168 /*
169 * when len <= n->m_len - off and off != 0, it is a special case.
170 * len bytes from <n, off> sits in single mbuf, but the caller does
171 * not like the starting position (off).
172 * chop the current mbuf into two pieces, set off to 0.
173 */
174 if (len <= n->m_len - off) {
175 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
176 if (o == NULL) {
177 m_freem(m);
178 return NULL; /* ENOBUFS */
179 }
180 n->m_len = off;
181 o->m_next = n->m_next;
182 n->m_next = o;
183 n = n->m_next;
184 off = 0;
185 goto ok;
186 }
187
188 /*
189 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
190 * and construct contiguous mbuf with m_len == len.
191 * note that hlen + tlen == len, and tlen > 0.
192 */
193 hlen = n->m_len - off;
194 tlen = len - hlen;
195
196 /*
197 * ensure that we have enough trailing data on mbuf chain.
198 * if not, we can do nothing about the chain.
199 */
200 olen = 0;
201 for (o = n->m_next; o != NULL; o = o->m_next)
202 olen += o->m_len;
203 if (hlen + olen < len) {
204 m_freem(m);
205 return NULL; /* mbuf chain too short */
206 }
207
208 /*
209 * easy cases first.
210 * we need to use m_copydata() to get data from <n->m_next, 0>.
211 */
212 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
213 && writable) {
214 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
215 n->m_len += tlen;
216 m_adj(n->m_next, tlen);
217 goto ok;
218 }
219 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
220 && writable) {
221 n->m_next->m_data -= hlen;
222 n->m_next->m_len += hlen;
223 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
224 n->m_len -= hlen;
225 n = n->m_next;
226 off = 0;
227 goto ok;
228 }
229
230 /*
231 * now, we need to do the hard way. don't m_copy as there's no room
232 * on both end.
233 */
234 if (len > MLEN)
235 o = m_getcl(M_DONTWAIT, m->m_type, 0);
236 else
237 o = m_get(M_DONTWAIT, m->m_type);
238 if (!o) {
239 m_freem(m);
240 return NULL; /* ENOBUFS */
241 }
242 /* get hlen from <n, off> into <o, 0> */
243 o->m_len = hlen;
244 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
245 n->m_len -= hlen;
246 /* get tlen from <n->m_next, 0> into <o, hlen> */
247 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
248 o->m_len += tlen;
249 m_adj(n->m_next, tlen);
250 o->m_next = n->m_next;
251 n->m_next = o;
252 n = o;
253 off = 0;
254
255 ok:
256 #ifdef PULLDOWN_DEBUG
257 {
258 struct mbuf *t;
259 printf("after:");
260 for (t = m; t; t = t->m_next)
261 printf("%c%d", t == n ? '*' : ' ', t->m_len);
262 printf(" (off=%d)\n", off);
263 }
264 #endif
265 if (offp)
266 *offp = off;
267 return n;
268 }
269
270 static struct mbuf *
271 m_dup1(struct mbuf *m, int off, int len, int wait)
272 {
273 struct mbuf *n;
274 int copyhdr;
275
276 if (len > MCLBYTES)
277 return NULL;
278 if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
279 copyhdr = 1;
280 else
281 copyhdr = 0;
282 if (len >= MINCLSIZE) {
283 if (copyhdr == 1)
284 n = m_getcl(wait, m->m_type, M_PKTHDR);
285 else
286 n = m_getcl(wait, m->m_type, 0);
287 } else {
288 if (copyhdr == 1)
289 n = m_gethdr(wait, m->m_type);
290 else
291 n = m_get(wait, m->m_type);
292 }
293 if (!n)
294 return NULL; /* ENOBUFS */
295
296 if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
297 m_free(n);
298 return NULL;
299 }
300 m_copydata(m, off, len, mtod(n, caddr_t));
301 n->m_len = len;
302 return n;
303 }
304
305 /* Free a packet tag. */
306 void
307 m_tag_free_default(struct m_tag *t)
308 {
309 #ifdef MAC
310 if (t->m_tag_id == PACKET_TAG_MACLABEL)
311 mac_destroy_mbuf_tag(t);
312 #endif
313 free(t, M_PACKET_TAGS);
314 }
315
316 /* Get a packet tag structure along with specified data following. */
317 struct m_tag *
318 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
319 {
320 struct m_tag *t;
321
322 MBUF_CHECKSLEEP(wait);
323 if (len < 0)
324 return NULL;
325 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
326 if (t == NULL)
327 return NULL;
328 m_tag_setup(t, cookie, type, len);
329 t->m_tag_free = m_tag_free_default;
330 return t;
331 }
332
333 /* Unlink and free a packet tag. */
334 void
335 m_tag_delete(struct mbuf *m, struct m_tag *t)
336 {
337
338 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
339 m_tag_unlink(m, t);
340 m_tag_free(t);
341 }
342
343 /* Unlink and free a packet tag chain, starting from given tag. */
344 void
345 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
346 {
347 struct m_tag *p, *q;
348
349 KASSERT(m, ("m_tag_delete_chain: null mbuf"));
350 if (t != NULL)
351 p = t;
352 else
353 p = SLIST_FIRST(&m->m_pkthdr.tags);
354 if (p == NULL)
355 return;
356 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
357 m_tag_delete(m, q);
358 m_tag_delete(m, p);
359 }
360
361 /*
362 * Strip off all tags that would normally vanish when
363 * passing through a network interface. Only persistent
364 * tags will exist after this; these are expected to remain
365 * so long as the mbuf chain exists, regardless of the
366 * path the mbufs take.
367 */
368 void
369 m_tag_delete_nonpersistent(struct mbuf *m)
370 {
371 struct m_tag *p, *q;
372
373 SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
374 if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
375 m_tag_delete(m, p);
376 }
377
378 /* Find a tag, starting from a given position. */
379 struct m_tag *
380 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
381 {
382 struct m_tag *p;
383
384 KASSERT(m, ("m_tag_locate: null mbuf"));
385 if (t == NULL)
386 p = SLIST_FIRST(&m->m_pkthdr.tags);
387 else
388 p = SLIST_NEXT(t, m_tag_link);
389 while (p != NULL) {
390 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
391 return p;
392 p = SLIST_NEXT(p, m_tag_link);
393 }
394 return NULL;
395 }
396
397 /* Copy a single tag. */
398 struct m_tag *
399 m_tag_copy(struct m_tag *t, int how)
400 {
401 struct m_tag *p;
402
403 MBUF_CHECKSLEEP(how);
404 KASSERT(t, ("m_tag_copy: null tag"));
405 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
406 if (p == NULL)
407 return (NULL);
408 #ifdef MAC
409 /*
410 * XXXMAC: we should probably pass off the initialization, and
411 * copying here? can we hide that PACKET_TAG_MACLABEL is
412 * special from the mbuf code?
413 */
414 if (t->m_tag_id == PACKET_TAG_MACLABEL) {
415 if (mac_init_mbuf_tag(p, how) != 0) {
416 m_tag_free(p);
417 return (NULL);
418 }
419 mac_copy_mbuf_tag(t, p);
420 } else
421 #endif
422 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
423 return p;
424 }
425
426 /*
427 * Copy two tag chains. The destination mbuf (to) loses any attached
428 * tags even if the operation fails. This should not be a problem, as
429 * m_tag_copy_chain() is typically called with a newly-allocated
430 * destination mbuf.
431 */
432 int
433 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
434 {
435 struct m_tag *p, *t, *tprev = NULL;
436
437 MBUF_CHECKSLEEP(how);
438 KASSERT(to && from,
439 ("m_tag_copy_chain: null argument, to %p from %p", to, from));
440 m_tag_delete_chain(to, NULL);
441 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
442 t = m_tag_copy(p, how);
443 if (t == NULL) {
444 m_tag_delete_chain(to, NULL);
445 return 0;
446 }
447 if (tprev == NULL)
448 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
449 else
450 SLIST_INSERT_AFTER(tprev, t, m_tag_link);
451 tprev = t;
452 }
453 return 1;
454 }
Cache object: 35b4032ca3f42bca9fce27caa7c4e7a2
|