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 82static 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 */ 86static 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 */ 98struct mbuf * 99m_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 256ok: 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 271static struct mbuf * 272m_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. */ 307void 308m_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. */ 318struct m_tag * 319m_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. */ 335void 336m_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. */ 345void 346m_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 */ 369void 370m_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. */ 380struct m_tag * 381m_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. */ 399struct m_tag * 400m_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 */ 433int 434m_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