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 * SPDX-License-Identifier: BSD-3-Clause
6 *
7 * Copyright (C) 1999 WIDE Project.
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the project nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34 /*-
35 * Copyright (c) 1982, 1986, 1988, 1991, 1993
36 * The Regents of the University of California. All rights reserved.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. Neither the name of the University nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60 * SUCH DAMAGE.
61 */
62
63 #include <sys/cdefs.h>
64 /*#define PULLDOWN_DEBUG*/
65
66 #include <sys/param.h>
67 #include <sys/systm.h>
68 #include <sys/kernel.h>
69 #include <sys/lock.h>
70 #include <sys/malloc.h>
71 #include <sys/mbuf.h>
72 #include <sys/mutex.h>
73
74 #include <security/mac/mac_framework.h>
75
76 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME,
77 "packet-attached information");
78
79 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
80 static struct mbuf *m_dup1(struct mbuf *, int, int, int);
81
82 /*
83 * ensure that [off, off + len) is contiguous on the mbuf chain "m".
84 * packet chain before "off" is kept untouched.
85 * if offp == NULL, the target will start at <retval, 0> on resulting chain.
86 * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
87 *
88 * on error return (NULL return value), original "m" will be freed.
89 *
90 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
91 */
92 struct mbuf *
m_pulldown(struct mbuf * m,int off,int len,int * offp)93 m_pulldown(struct mbuf *m, int off, int len, int *offp)
94 {
95 struct mbuf *n, *o;
96 int hlen, tlen, olen;
97 int writable;
98
99 /* check invalid arguments. */
100 KASSERT(m != NULL, ("%s: fix caller: m is NULL off %d len %d offp %p\n",
101 __func__, off, len, offp));
102 if (len > MCLBYTES) {
103 m_freem(m);
104 return NULL; /* impossible */
105 }
106
107 #ifdef PULLDOWN_DEBUG
108 {
109 struct mbuf *t;
110 printf("before:");
111 for (t = m; t; t = t->m_next)
112 printf(" %d", t->m_len);
113 printf("\n");
114 }
115 #endif
116 n = m;
117 while (n != NULL && off > 0) {
118 if (n->m_len > off)
119 break;
120 off -= n->m_len;
121 n = n->m_next;
122 }
123 /* be sure to point non-empty mbuf */
124 while (n != NULL && n->m_len == 0)
125 n = n->m_next;
126 if (!n) {
127 m_freem(m);
128 return NULL; /* mbuf chain too short */
129 }
130
131 /*
132 * The following comment is dated but still partially applies:
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 possession 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 writable = 0;
152 if ((n->m_flags & M_EXT) == 0 ||
153 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
154 writable = 1;
155
156 /*
157 * the target data is on <n, off>.
158 * if we got enough data on the mbuf "n", we're done.
159 */
160 if ((off == 0 || offp) && len <= n->m_len - off)
161 goto ok;
162
163 /*
164 * when len <= n->m_len - off and off != 0, it is a special case.
165 * len bytes from <n, off> sits in single mbuf, but the caller does
166 * not like the starting position (off).
167 * chop the current mbuf into two pieces, set off to 0.
168 */
169 if (len <= n->m_len - off) {
170 o = m_dup1(n, off, n->m_len - off, M_NOWAIT);
171 if (o == NULL) {
172 m_freem(m);
173 return NULL; /* ENOBUFS */
174 }
175 n->m_len = off;
176 o->m_next = n->m_next;
177 n->m_next = o;
178 n = n->m_next;
179 off = 0;
180 goto ok;
181 }
182
183 /*
184 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
185 * and construct contiguous mbuf with m_len == len.
186 * note that hlen + tlen == len, and tlen > 0.
187 */
188 hlen = n->m_len - off;
189 tlen = len - hlen;
190
191 /*
192 * ensure that we have enough trailing data on mbuf chain.
193 * if not, we can do nothing about the chain.
194 */
195 olen = 0;
196 for (o = n->m_next; o != NULL; o = o->m_next)
197 olen += o->m_len;
198 if (hlen + olen < len) {
199 m_freem(m);
200 return NULL; /* mbuf chain too short */
201 }
202
203 /*
204 * easy cases first.
205 * we need to use m_copydata() to get data from <n->m_next, 0>.
206 */
207 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
208 && writable) {
209 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
210 n->m_len += tlen;
211 m_adj(n->m_next, tlen);
212 goto ok;
213 }
214 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
215 && writable && n->m_next->m_len >= tlen) {
216 n->m_next->m_data -= hlen;
217 n->m_next->m_len += hlen;
218 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
219 n->m_len -= hlen;
220 n = n->m_next;
221 off = 0;
222 goto ok;
223 }
224
225 /*
226 * now, we need to do the hard way. don't m_copy as there's no room
227 * on both end.
228 */
229 if (len > MLEN)
230 o = m_getcl(M_NOWAIT, m->m_type, 0);
231 else
232 o = m_get(M_NOWAIT, m->m_type);
233 if (!o) {
234 m_freem(m);
235 return NULL; /* ENOBUFS */
236 }
237 /* get hlen from <n, off> into <o, 0> */
238 o->m_len = hlen;
239 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
240 n->m_len -= hlen;
241 /* get tlen from <n->m_next, 0> into <o, hlen> */
242 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
243 o->m_len += tlen;
244 m_adj(n->m_next, tlen);
245 o->m_next = n->m_next;
246 n->m_next = o;
247 n = o;
248 off = 0;
249
250 ok:
251 #ifdef PULLDOWN_DEBUG
252 {
253 struct mbuf *t;
254 printf("after:");
255 for (t = m; t; t = t->m_next)
256 printf("%c%d", t == n ? '*' : ' ', t->m_len);
257 printf(" (off=%d)\n", off);
258 }
259 #endif
260 if (offp)
261 *offp = off;
262 return n;
263 }
264
265 static struct mbuf *
m_dup1(struct mbuf * m,int off,int len,int wait)266 m_dup1(struct mbuf *m, int off, int len, int wait)
267 {
268 struct mbuf *n;
269 int copyhdr;
270
271 if (len > MCLBYTES)
272 return NULL;
273 if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
274 copyhdr = 1;
275 else
276 copyhdr = 0;
277 if (len >= MINCLSIZE) {
278 if (copyhdr == 1)
279 n = m_getcl(wait, m->m_type, M_PKTHDR);
280 else
281 n = m_getcl(wait, m->m_type, 0);
282 } else {
283 if (copyhdr == 1)
284 n = m_gethdr(wait, m->m_type);
285 else
286 n = m_get(wait, m->m_type);
287 }
288 if (!n)
289 return NULL; /* ENOBUFS */
290
291 if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
292 m_free(n);
293 return NULL;
294 }
295 m_copydata(m, off, len, mtod(n, caddr_t));
296 n->m_len = len;
297 return n;
298 }
299
300 /* Free a packet tag. */
301 void
m_tag_free_default(struct m_tag * t)302 m_tag_free_default(struct m_tag *t)
303 {
304 #ifdef MAC
305 if (t->m_tag_id == PACKET_TAG_MACLABEL)
306 mac_mbuf_tag_destroy(t);
307 #endif
308 free(t, M_PACKET_TAGS);
309 }
310
311 /* Get a packet tag structure along with specified data following. */
312 struct m_tag *
m_tag_alloc(uint32_t cookie,uint16_t type,int len,int wait)313 m_tag_alloc(uint32_t cookie, uint16_t type, int len, int wait)
314 {
315 struct m_tag *t;
316
317 MBUF_CHECKSLEEP(wait);
318 if (len < 0)
319 return NULL;
320 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
321 if (t == NULL)
322 return NULL;
323 m_tag_setup(t, cookie, type, len);
324 t->m_tag_free = m_tag_free_default;
325 return t;
326 }
327
328 /* Unlink and free a packet tag. */
329 void
m_tag_delete(struct mbuf * m,struct m_tag * t)330 m_tag_delete(struct mbuf *m, struct m_tag *t)
331 {
332
333 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
334 m_tag_unlink(m, t);
335 m_tag_free(t);
336 }
337
338 /* Unlink and free a packet tag chain, starting from given tag. */
339 void
m_tag_delete_chain(struct mbuf * m,struct m_tag * t)340 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
341 {
342 struct m_tag *p, *q;
343
344 KASSERT(m, ("m_tag_delete_chain: null mbuf"));
345 if (t != NULL)
346 p = t;
347 else
348 p = SLIST_FIRST(&m->m_pkthdr.tags);
349 if (p == NULL)
350 return;
351 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
352 m_tag_delete(m, q);
353 m_tag_delete(m, p);
354 }
355
356 /*
357 * Strip off all tags that would normally vanish when
358 * passing through a network interface. Only persistent
359 * tags will exist after this; these are expected to remain
360 * so long as the mbuf chain exists, regardless of the
361 * path the mbufs take.
362 */
363 void
m_tag_delete_nonpersistent(struct mbuf * m)364 m_tag_delete_nonpersistent(struct mbuf *m)
365 {
366 struct m_tag *p, *q;
367
368 SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
369 if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
370 m_tag_delete(m, p);
371 }
372
373 /* Find a tag, starting from a given position. */
374 struct m_tag *
m_tag_locate(struct mbuf * m,uint32_t cookie,uint16_t type,struct m_tag * t)375 m_tag_locate(struct mbuf *m, uint32_t cookie, uint16_t type, struct m_tag *t)
376 {
377 struct m_tag *p;
378
379 KASSERT(m, ("m_tag_locate: null mbuf"));
380 if (t == NULL)
381 p = SLIST_FIRST(&m->m_pkthdr.tags);
382 else
383 p = SLIST_NEXT(t, m_tag_link);
384 while (p != NULL) {
385 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
386 return p;
387 p = SLIST_NEXT(p, m_tag_link);
388 }
389 return NULL;
390 }
391
392 /* Copy a single tag. */
393 struct m_tag *
m_tag_copy(struct m_tag * t,int how)394 m_tag_copy(struct m_tag *t, int how)
395 {
396 struct m_tag *p;
397
398 MBUF_CHECKSLEEP(how);
399 KASSERT(t, ("m_tag_copy: null tag"));
400 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
401 if (p == NULL)
402 return (NULL);
403 #ifdef MAC
404 /*
405 * XXXMAC: we should probably pass off the initialization, and
406 * copying here? can we hide that PACKET_TAG_MACLABEL is
407 * special from the mbuf code?
408 */
409 if (t->m_tag_id == PACKET_TAG_MACLABEL) {
410 if (mac_mbuf_tag_init(p, how) != 0) {
411 m_tag_free(p);
412 return (NULL);
413 }
414 mac_mbuf_tag_copy(t, p);
415 } else
416 #endif
417 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
418 return p;
419 }
420
421 /*
422 * Copy two tag chains. The destination mbuf (to) loses any attached
423 * tags even if the operation fails. This should not be a problem, as
424 * m_tag_copy_chain() is typically called with a newly-allocated
425 * destination mbuf.
426 */
427 int
m_tag_copy_chain(struct mbuf * to,const struct mbuf * from,int how)428 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
429 {
430 struct m_tag *p, *t, *tprev = NULL;
431
432 MBUF_CHECKSLEEP(how);
433 KASSERT(to && from,
434 ("m_tag_copy_chain: null argument, to %p from %p", to, from));
435 m_tag_delete_chain(to, NULL);
436 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
437 t = m_tag_copy(p, how);
438 if (t == NULL) {
439 m_tag_delete_chain(to, NULL);
440 return 0;
441 }
442 if (tprev == NULL)
443 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
444 else
445 SLIST_INSERT_AFTER(tprev, t, m_tag_link);
446 tprev = t;
447 }
448 return 1;
449 }
450