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 * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95 63 */ 64 65 #include <sys/cdefs.h> 66 __FBSDID("$FreeBSD$"); 67 68 /*#define PULLDOWN_DEBUG*/ 69 70 #include <sys/param.h> 71 #include <sys/systm.h> 72 #include <sys/kernel.h> 73 #include <sys/lock.h> 74 #include <sys/malloc.h> 75 #include <sys/mbuf.h> 76 #include <sys/mutex.h> 77 78 #include <security/mac/mac_framework.h> 79 80 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME, 81 "packet-attached information"); 82 83 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ 84 static struct mbuf *m_dup1(struct mbuf *, int, int, int); 85 86 /* 87 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 88 * packet chain before "off" is kept untouched. 89 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 90 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 91 * 92 * on error return (NULL return value), original "m" will be freed. 93 * 94 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 95 */ 96 struct mbuf * 97 m_pulldown(struct mbuf *m, int off, int len, int *offp) 98 { 99 struct mbuf *n, *o; 100 int hlen, tlen, olen; 101 int writable; 102 103 /* check invalid arguments. */ 104 KASSERT(m != NULL, ("%s: fix caller: m is NULL off %d len %d offp %p\n", 105 __func__, off, len, offp)); 106 if (len > MCLBYTES) { 107 m_freem(m); 108 return NULL; /* impossible */ 109 } 110 111 #ifdef PULLDOWN_DEBUG 112 { 113 struct mbuf *t; 114 printf("before:"); 115 for (t = m; t; t = t->m_next) 116 printf(" %d", t->m_len); 117 printf("\n"); 118 } 119 #endif 120 n = m; 121 while (n != NULL && off > 0) { 122 if (n->m_len > off) 123 break; 124 off -= n->m_len; 125 n = n->m_next; 126 } 127 /* be sure to point non-empty mbuf */ 128 while (n != NULL && n->m_len == 0) 129 n = n->m_next; 130 if (!n) { 131 m_freem(m); 132 return NULL; /* mbuf chain too short */ 133 } 134 135 /* 136 * The following comment is dated but still partially applies: 137 * 138 * XXX: This code is flawed because it considers a "writable" mbuf 139 * data region to require all of the following: 140 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 141 * mbuf, it is still not considered "writable." 142 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 143 * EXT_CLUSTER. Anything else makes it non-writable. 144 * (iii) M_WRITABLE() must evaluate true. 145 * Ideally, the requirement should only be (iii). 146 * 147 * If we're writable, we're sure we're writable, because the ref. count 148 * cannot increase from 1, as that would require possession of mbuf 149 * n by someone else (which is impossible). However, if we're _not_ 150 * writable, we may eventually become writable )if the ref. count drops 151 * to 1), but we'll fail to notice it unless we re-evaluate 152 * M_WRITABLE(). For now, we only evaluate once at the beginning and 153 * live with this. 154 */ 155 writable = 0; 156 if ((n->m_flags & M_EXT) == 0 || 157 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) 158 writable = 1; 159 160 /* 161 * the target data is on <n, off>. 162 * if we got enough data on the mbuf "n", we're done. 163 */ 164 if ((off == 0 || offp) && len <= n->m_len - off) 165 goto ok; 166 167 /* 168 * when len <= n->m_len - off and off != 0, it is a special case. 169 * len bytes from <n, off> sits in single mbuf, but the caller does 170 * not like the starting position (off). 171 * chop the current mbuf into two pieces, set off to 0. 172 */ 173 if (len <= n->m_len - off) { 174 o = m_dup1(n, off, n->m_len - off, M_NOWAIT); 175 if (o == NULL) { 176 m_freem(m); 177 return NULL; /* ENOBUFS */ 178 } 179 n->m_len = off; 180 o->m_next = n->m_next; 181 n->m_next = o; 182 n = n->m_next; 183 off = 0; 184 goto ok; 185 } 186 187 /* 188 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 189 * and construct contiguous mbuf with m_len == len. 190 * note that hlen + tlen == len, and tlen > 0. 191 */ 192 hlen = n->m_len - off; 193 tlen = len - hlen; 194 195 /* 196 * ensure that we have enough trailing data on mbuf chain. 197 * if not, we can do nothing about the chain. 198 */ 199 olen = 0; 200 for (o = n->m_next; o != NULL; o = o->m_next) 201 olen += o->m_len; 202 if (hlen + olen < len) { 203 m_freem(m); 204 return NULL; /* mbuf chain too short */ 205 } 206 207 /* 208 * easy cases first. 209 * we need to use m_copydata() to get data from <n->m_next, 0>. 210 */ 211 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 212 && writable) { 213 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 214 n->m_len += tlen; 215 m_adj(n->m_next, tlen); 216 goto ok; 217 } 218 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 219 && writable && n->m_next->m_len >= tlen) { 220 n->m_next->m_data -= hlen; 221 n->m_next->m_len += hlen; 222 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 223 n->m_len -= hlen; 224 n = n->m_next; 225 off = 0; 226 goto ok; 227 } 228 229 /* 230 * now, we need to do the hard way. don't m_copy as there's no room 231 * on both end. 232 */ 233 if (len > MLEN) 234 o = m_getcl(M_NOWAIT, m->m_type, 0); 235 else 236 o = m_get(M_NOWAIT, m->m_type); 237 if (!o) { 238 m_freem(m); 239 return NULL; /* ENOBUFS */ 240 } 241 /* get hlen from <n, off> into <o, 0> */ 242 o->m_len = hlen; 243 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 244 n->m_len -= hlen; 245 /* get tlen from <n->m_next, 0> into <o, hlen> */ 246 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 247 o->m_len += tlen; 248 m_adj(n->m_next, tlen); 249 o->m_next = n->m_next; 250 n->m_next = o; 251 n = o; 252 off = 0; 253 254 ok: 255 #ifdef PULLDOWN_DEBUG 256 { 257 struct mbuf *t; 258 printf("after:"); 259 for (t = m; t; t = t->m_next) 260 printf("%c%d", t == n ? '*' : ' ', t->m_len); 261 printf(" (off=%d)\n", off); 262 } 263 #endif 264 if (offp) 265 *offp = off; 266 return n; 267 } 268 269 static struct mbuf * 270 m_dup1(struct mbuf *m, int off, int len, int wait) 271 { 272 struct mbuf *n; 273 int copyhdr; 274 275 if (len > MCLBYTES) 276 return NULL; 277 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) 278 copyhdr = 1; 279 else 280 copyhdr = 0; 281 if (len >= MINCLSIZE) { 282 if (copyhdr == 1) 283 n = m_getcl(wait, m->m_type, M_PKTHDR); 284 else 285 n = m_getcl(wait, m->m_type, 0); 286 } else { 287 if (copyhdr == 1) 288 n = m_gethdr(wait, m->m_type); 289 else 290 n = m_get(wait, m->m_type); 291 } 292 if (!n) 293 return NULL; /* ENOBUFS */ 294 295 if (copyhdr && !m_dup_pkthdr(n, m, wait)) { 296 m_free(n); 297 return NULL; 298 } 299 m_copydata(m, off, len, mtod(n, caddr_t)); 300 n->m_len = len; 301 return n; 302 } 303 304 /* Free a packet tag. */ 305 void 306 m_tag_free_default(struct m_tag *t) 307 { 308 #ifdef MAC 309 if (t->m_tag_id == PACKET_TAG_MACLABEL) 310 mac_mbuf_tag_destroy(t); 311 #endif 312 free(t, M_PACKET_TAGS); 313 } 314 315 /* Get a packet tag structure along with specified data following. */ 316 struct m_tag * 317 m_tag_alloc(uint32_t cookie, int type, int len, int wait) 318 { 319 struct m_tag *t; 320 321 MBUF_CHECKSLEEP(wait); 322 if (len < 0) 323 return NULL; 324 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait); 325 if (t == NULL) 326 return NULL; 327 m_tag_setup(t, cookie, type, len); 328 t->m_tag_free = m_tag_free_default; 329 return t; 330 } 331 332 /* Unlink and free a packet tag. */ 333 void 334 m_tag_delete(struct mbuf *m, struct m_tag *t) 335 { 336 337 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); 338 m_tag_unlink(m, t); 339 m_tag_free(t); 340 } 341 342 /* Unlink and free a packet tag chain, starting from given tag. */ 343 void 344 m_tag_delete_chain(struct mbuf *m, struct m_tag *t) 345 { 346 struct m_tag *p, *q; 347 348 KASSERT(m, ("m_tag_delete_chain: null mbuf")); 349 if (t != NULL) 350 p = t; 351 else 352 p = SLIST_FIRST(&m->m_pkthdr.tags); 353 if (p == NULL) 354 return; 355 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) 356 m_tag_delete(m, q); 357 m_tag_delete(m, p); 358 } 359 360 /* 361 * Strip off all tags that would normally vanish when 362 * passing through a network interface. Only persistent 363 * tags will exist after this; these are expected to remain 364 * so long as the mbuf chain exists, regardless of the 365 * path the mbufs take. 366 */ 367 void 368 m_tag_delete_nonpersistent(struct mbuf *m) 369 { 370 struct m_tag *p, *q; 371 372 SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q) 373 if ((p->m_tag_id & MTAG_PERSISTENT) == 0) 374 m_tag_delete(m, p); 375 } 376 377 /* Find a tag, starting from a given position. */ 378 struct m_tag * 379 m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t) 380 { 381 struct m_tag *p; 382 383 KASSERT(m, ("m_tag_locate: null mbuf")); 384 if (t == NULL) 385 p = SLIST_FIRST(&m->m_pkthdr.tags); 386 else 387 p = SLIST_NEXT(t, m_tag_link); 388 while (p != NULL) { 389 if (p->m_tag_cookie == cookie && p->m_tag_id == type) 390 return p; 391 p = SLIST_NEXT(p, m_tag_link); 392 } 393 return NULL; 394 } 395 396 /* Copy a single tag. */ 397 struct m_tag * 398 m_tag_copy(struct m_tag *t, int how) 399 { 400 struct m_tag *p; 401 402 MBUF_CHECKSLEEP(how); 403 KASSERT(t, ("m_tag_copy: null tag")); 404 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); 405 if (p == NULL) 406 return (NULL); 407 #ifdef MAC 408 /* 409 * XXXMAC: we should probably pass off the initialization, and 410 * copying here? can we hide that PACKET_TAG_MACLABEL is 411 * special from the mbuf code? 412 */ 413 if (t->m_tag_id == PACKET_TAG_MACLABEL) { 414 if (mac_mbuf_tag_init(p, how) != 0) { 415 m_tag_free(p); 416 return (NULL); 417 } 418 mac_mbuf_tag_copy(t, p); 419 } else 420 #endif 421 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ 422 return p; 423 } 424 425 /* 426 * Copy two tag chains. The destination mbuf (to) loses any attached 427 * tags even if the operation fails. This should not be a problem, as 428 * m_tag_copy_chain() is typically called with a newly-allocated 429 * destination mbuf. 430 */ 431 int 432 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how) 433 { 434 struct m_tag *p, *t, *tprev = NULL; 435 436 MBUF_CHECKSLEEP(how); 437 KASSERT(to && from, 438 ("m_tag_copy_chain: null argument, to %p from %p", to, from)); 439 m_tag_delete_chain(to, NULL); 440 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) { 441 t = m_tag_copy(p, how); 442 if (t == NULL) { 443 m_tag_delete_chain(to, NULL); 444 return 0; 445 } 446 if (tprev == NULL) 447 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link); 448 else 449 SLIST_INSERT_AFTER(tprev, t, m_tag_link); 450 tprev = t; 451 } 452 return 1; 453 } 454