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("$FreeBSD$");
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 KASSERT(m != NULL, ("%s: fix caller: m is NULL off %d len %d offp %p\n",
103 __func__, off, len, offp));
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 * The following comment is dated but still partially applies:
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 possession 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 writable = 0;
154 if ((n->m_flags & M_EXT) == 0 ||
155 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
156 writable = 1;
157
158 /*
159 * the target data is on <n, off>.
160 * if we got enough data on the mbuf "n", we're done.
161 */
162 if ((off == 0 || offp) && len <= n->m_len - off)
163 goto ok;
164
165 /*
166 * when len <= n->m_len - off and off != 0, it is a special case.
167 * len bytes from <n, off> sits in single mbuf, but the caller does
168 * not like the starting position (off).
169 * chop the current mbuf into two pieces, set off to 0.
170 */
171 if (len <= n->m_len - off) {
172 o = m_dup1(n, off, n->m_len - off, M_NOWAIT);
173 if (o == NULL) {
174 m_freem(m);
175 return NULL; /* ENOBUFS */
176 }
177 n->m_len = off;
178 o->m_next = n->m_next;
179 n->m_next = o;
180 n = n->m_next;
181 off = 0;
182 goto ok;
183 }
184
185 /*
186 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
187 * and construct contiguous mbuf with m_len == len.
188 * note that hlen + tlen == len, and tlen > 0.
189 */
190 hlen = n->m_len - off;
191 tlen = len - hlen;
192
193 /*
194 * ensure that we have enough trailing data on mbuf chain.
195 * if not, we can do nothing about the chain.
196 */
197 olen = 0;
198 for (o = n->m_next; o != NULL; o = o->m_next)
199 olen += o->m_len;
200 if (hlen + olen < len) {
201 m_freem(m);
202 return NULL; /* mbuf chain too short */
203 }
204
205 /*
206 * easy cases first.
207 * we need to use m_copydata() to get data from <n->m_next, 0>.
208 */
209 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
210 && writable) {
211 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
212 n->m_len += tlen;
213 m_adj(n->m_next, tlen);
214 goto ok;
215 }
216 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
217 && writable && n->m_next->m_len >= tlen) {
218 n->m_next->m_data -= hlen;
219 n->m_next->m_len += hlen;
220 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
221 n->m_len -= hlen;
222 n = n->m_next;
223 off = 0;
224 goto ok;
225 }
226
227 /*
228 * now, we need to do the hard way. don't m_copy as there's no room
229 * on both end.
230 */
231 if (len > MLEN)
232 o = m_getcl(M_NOWAIT, m->m_type, 0);
233 else
234 o = m_get(M_NOWAIT, m->m_type);
235 if (!o) {
236 m_freem(m);
237 return NULL; /* ENOBUFS */
238 }
239 /* get hlen from <n, off> into <o, 0> */
240 o->m_len = hlen;
241 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
242 n->m_len -= hlen;
243 /* get tlen from <n->m_next, 0> into <o, hlen> */
244 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
245 o->m_len += tlen;
246 m_adj(n->m_next, tlen);
247 o->m_next = n->m_next;
248 n->m_next = o;
249 n = o;
250 off = 0;
251
252 ok:
253 #ifdef PULLDOWN_DEBUG
254 {
255 struct mbuf *t;
256 printf("after:");
257 for (t = m; t; t = t->m_next)
258 printf("%c%d", t == n ? '*' : ' ', t->m_len);
259 printf(" (off=%d)\n", off);
260 }
261 #endif
262 if (offp)
263 *offp = off;
264 return n;
265 }
266
267 static struct mbuf *
268 m_dup1(struct mbuf *m, int off, int len, int wait)
269 {
270 struct mbuf *n;
271 int copyhdr;
272
273 if (len > MCLBYTES)
274 return NULL;
275 if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
276 copyhdr = 1;
277 else
278 copyhdr = 0;
279 if (len >= MINCLSIZE) {
280 if (copyhdr == 1)
281 n = m_getcl(wait, m->m_type, M_PKTHDR);
282 else
283 n = m_getcl(wait, m->m_type, 0);
284 } else {
285 if (copyhdr == 1)
286 n = m_gethdr(wait, m->m_type);
287 else
288 n = m_get(wait, m->m_type);
289 }
290 if (!n)
291 return NULL; /* ENOBUFS */
292
293 if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
294 m_free(n);
295 return NULL;
296 }
297 m_copydata(m, off, len, mtod(n, caddr_t));
298 n->m_len = len;
299 return n;
300 }
301
302 /* Free a packet tag. */
303 void
304 m_tag_free_default(struct m_tag *t)
305 {
306 #ifdef MAC
307 if (t->m_tag_id == PACKET_TAG_MACLABEL)
308 mac_mbuf_tag_destroy(t);
309 #endif
310 free(t, M_PACKET_TAGS);
311 }
312
313 /* Get a packet tag structure along with specified data following. */
314 struct m_tag *
315 m_tag_alloc(uint32_t cookie, int type, int len, int wait)
316 {
317 struct m_tag *t;
318
319 MBUF_CHECKSLEEP(wait);
320 if (len < 0)
321 return NULL;
322 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
323 if (t == NULL)
324 return NULL;
325 m_tag_setup(t, cookie, type, len);
326 t->m_tag_free = m_tag_free_default;
327 return t;
328 }
329
330 /* Unlink and free a packet tag. */
331 void
332 m_tag_delete(struct mbuf *m, struct m_tag *t)
333 {
334
335 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
336 m_tag_unlink(m, t);
337 m_tag_free(t);
338 }
339
340 /* Unlink and free a packet tag chain, starting from given tag. */
341 void
342 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
343 {
344 struct m_tag *p, *q;
345
346 KASSERT(m, ("m_tag_delete_chain: null mbuf"));
347 if (t != NULL)
348 p = t;
349 else
350 p = SLIST_FIRST(&m->m_pkthdr.tags);
351 if (p == NULL)
352 return;
353 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
354 m_tag_delete(m, q);
355 m_tag_delete(m, p);
356 }
357
358 /*
359 * Strip off all tags that would normally vanish when
360 * passing through a network interface. Only persistent
361 * tags will exist after this; these are expected to remain
362 * so long as the mbuf chain exists, regardless of the
363 * path the mbufs take.
364 */
365 void
366 m_tag_delete_nonpersistent(struct mbuf *m)
367 {
368 struct m_tag *p, *q;
369
370 SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
371 if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
372 m_tag_delete(m, p);
373 }
374
375 /* Find a tag, starting from a given position. */
376 struct m_tag *
377 m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t)
378 {
379 struct m_tag *p;
380
381 KASSERT(m, ("m_tag_locate: null mbuf"));
382 if (t == NULL)
383 p = SLIST_FIRST(&m->m_pkthdr.tags);
384 else
385 p = SLIST_NEXT(t, m_tag_link);
386 while (p != NULL) {
387 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
388 return p;
389 p = SLIST_NEXT(p, m_tag_link);
390 }
391 return NULL;
392 }
393
394 /* Copy a single tag. */
395 struct m_tag *
396 m_tag_copy(struct m_tag *t, int how)
397 {
398 struct m_tag *p;
399
400 MBUF_CHECKSLEEP(how);
401 KASSERT(t, ("m_tag_copy: null tag"));
402 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
403 if (p == NULL)
404 return (NULL);
405 #ifdef MAC
406 /*
407 * XXXMAC: we should probably pass off the initialization, and
408 * copying here? can we hide that PACKET_TAG_MACLABEL is
409 * special from the mbuf code?
410 */
411 if (t->m_tag_id == PACKET_TAG_MACLABEL) {
412 if (mac_mbuf_tag_init(p, how) != 0) {
413 m_tag_free(p);
414 return (NULL);
415 }
416 mac_mbuf_tag_copy(t, p);
417 } else
418 #endif
419 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
420 return p;
421 }
422
423 /*
424 * Copy two tag chains. The destination mbuf (to) loses any attached
425 * tags even if the operation fails. This should not be a problem, as
426 * m_tag_copy_chain() is typically called with a newly-allocated
427 * destination mbuf.
428 */
429 int
430 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
431 {
432 struct m_tag *p, *t, *tprev = NULL;
433
434 MBUF_CHECKSLEEP(how);
435 KASSERT(to && from,
436 ("m_tag_copy_chain: null argument, to %p from %p", to, from));
437 m_tag_delete_chain(to, NULL);
438 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
439 t = m_tag_copy(p, how);
440 if (t == NULL) {
441 m_tag_delete_chain(to, NULL);
442 return 0;
443 }
444 if (tprev == NULL)
445 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
446 else
447 SLIST_INSERT_AFTER(tprev, t, m_tag_link);
448 tprev = t;
449 }
450 return 1;
451 }
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