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: stable/11/sys/kern/uipc_mbuf2.c 312441 2017-01-19 23:42:51Z rpokala $");
65
66 /*#define PULLDOWN_DEBUG*/
67
68 #ifdef __HAIKU__
69 #define FBSD_DRIVER
70 #endif
71
72 #include <sys/param.h>
73 #include <sys/systm.h>
74 #include <sys/kernel.h>
75 #include <sys/lock.h>
76 #include <sys/malloc.h>
77 #include <sys/mbuf.h>
78 #include <sys/mutex.h>
79
80 #include <security/mac/mac_framework.h>
81
82 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME,
83 "packet-attached information");
84
85 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
86 static struct mbuf *m_dup1(struct mbuf *, int, int, int);
87
88 /*
89 * ensure that [off, off + len) is contiguous on the mbuf chain "m".
90 * packet chain before "off" is kept untouched.
91 * if offp == NULL, the target will start at <retval, 0> on resulting chain.
92 * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
93 *
94 * on error return (NULL return value), original "m" will be freed.
95 *
96 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
97 */
98 struct mbuf *
m_pulldown(struct mbuf * m,int off,int len,int * offp)99 m_pulldown(struct mbuf *m, int off, int len, int *offp)
100 {
101 struct mbuf *n, *o;
102 int hlen, tlen, olen;
103 int writable;
104
105 /* check invalid arguments. */
106 if (m == NULL)
107 panic("m == NULL in m_pulldown()");
108 if (len > MCLBYTES) {
109 m_freem(m);
110 return NULL; /* impossible */
111 }
112
113 #ifdef PULLDOWN_DEBUG
114 {
115 struct mbuf *t;
116 printf("before:");
117 for (t = m; t; t = t->m_next)
118 printf(" %d", t->m_len);
119 printf("\n");
120 }
121 #endif
122 n = m;
123 while (n != NULL && off > 0) {
124 if (n->m_len > off)
125 break;
126 off -= n->m_len;
127 n = n->m_next;
128 }
129 /* be sure to point non-empty mbuf */
130 while (n != NULL && n->m_len == 0)
131 n = n->m_next;
132 if (!n) {
133 m_freem(m);
134 return NULL; /* mbuf chain too short */
135 }
136
137 /*
138 * The following comment is dated but still partially applies:
139 *
140 * XXX: This code is flawed because it considers a "writable" mbuf
141 * data region to require all of the following:
142 * (i) mbuf _has_ to have M_EXT set; if it is just a regular
143 * mbuf, it is still not considered "writable."
144 * (ii) since mbuf has M_EXT, the ext_type _has_ to be
145 * EXT_CLUSTER. Anything else makes it non-writable.
146 * (iii) M_WRITABLE() must evaluate true.
147 * Ideally, the requirement should only be (iii).
148 *
149 * If we're writable, we're sure we're writable, because the ref. count
150 * cannot increase from 1, as that would require possession of mbuf
151 * n by someone else (which is impossible). However, if we're _not_
152 * writable, we may eventually become writable )if the ref. count drops
153 * to 1), but we'll fail to notice it unless we re-evaluate
154 * M_WRITABLE(). For now, we only evaluate once at the beginning and
155 * live with this.
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)
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_NOWAIT);
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_NOWAIT, m->m_type, 0);
237 else
238 o = m_get(M_NOWAIT, 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 *
m_dup1(struct mbuf * m,int off,int len,int wait)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
m_tag_free_default(struct m_tag * t)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 *
m_tag_alloc(uint32_t cookie,int type,int len,int wait)319 m_tag_alloc(uint32_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
m_tag_delete(struct mbuf * m,struct m_tag * t)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
m_tag_delete_chain(struct mbuf * m,struct m_tag * t)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
m_tag_delete_nonpersistent(struct mbuf * m)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 *
m_tag_locate(struct mbuf * m,uint32_t cookie,int type,struct m_tag * t)381 m_tag_locate(struct mbuf *m, uint32_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 *
m_tag_copy(struct m_tag * t,int how)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
m_tag_copy_chain(struct mbuf * to,const struct mbuf * from,int how)434 m_tag_copy_chain(struct mbuf *to, const 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 }
456