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 * 3. All advertising materials mentioning features or use of this software 45 * must display the following acknowledgement: 46 * This product includes software developed by the University of 47 * California, Berkeley and its contributors. 48 * 4. Neither the name of the University nor the names of its contributors 49 * may be used to endorse or promote products derived from this software 50 * without specific prior written permission. 51 * 52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 62 * SUCH DAMAGE. 63 * 64 * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95 65 */ 66 67 #include <sys/cdefs.h> 68 __FBSDID("$FreeBSD$"); 69 70 /*#define PULLDOWN_DEBUG*/ 71 72 #include "opt_mac.h" 73 74 #include <sys/param.h> 75 #include <sys/systm.h> 76 #include <sys/kernel.h> 77 #include <sys/lock.h> 78 #include <sys/mac.h> 79 #include <sys/malloc.h> 80 #include <sys/mbuf.h> 81 #include <sys/mutex.h> 82 83 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "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 * 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 * 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 posession 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 /* 156 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 157 * then we're not "writable," according to this code. 158 */ 159 writable = 0; 160 if ((n->m_flags & M_EXT) == 0 || 161 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) 162 writable = 1; 163 164 /* 165 * the target data is on <n, off>. 166 * if we got enough data on the mbuf "n", we're done. 167 */ 168 if ((off == 0 || offp) && len <= n->m_len - off && writable) 169 goto ok; 170 171 /* 172 * when len <= n->m_len - off and off != 0, it is a special case. 173 * len bytes from <n, off> sits in single mbuf, but the caller does 174 * not like the starting position (off). 175 * chop the current mbuf into two pieces, set off to 0. 176 */ 177 if (len <= n->m_len - off) { 178 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT); 179 if (o == NULL) { 180 m_freem(m); 181 return NULL; /* ENOBUFS */ 182 } 183 n->m_len = off; 184 o->m_next = n->m_next; 185 n->m_next = o; 186 n = n->m_next; 187 off = 0; 188 goto ok; 189 } 190 191 /* 192 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 193 * and construct contiguous mbuf with m_len == len. 194 * note that hlen + tlen == len, and tlen > 0. 195 */ 196 hlen = n->m_len - off; 197 tlen = len - hlen; 198 199 /* 200 * ensure that we have enough trailing data on mbuf chain. 201 * if not, we can do nothing about the chain. 202 */ 203 olen = 0; 204 for (o = n->m_next; o != NULL; o = o->m_next) 205 olen += o->m_len; 206 if (hlen + olen < len) { 207 m_freem(m); 208 return NULL; /* mbuf chain too short */ 209 } 210 211 /* 212 * easy cases first. 213 * we need to use m_copydata() to get data from <n->m_next, 0>. 214 */ 215 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 216 && writable) { 217 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 218 n->m_len += tlen; 219 m_adj(n->m_next, tlen); 220 goto ok; 221 } 222 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 223 && writable) { 224 n->m_next->m_data -= hlen; 225 n->m_next->m_len += hlen; 226 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 227 n->m_len -= hlen; 228 n = n->m_next; 229 off = 0; 230 goto ok; 231 } 232 233 /* 234 * now, we need to do the hard way. don't m_copy as there's no room 235 * on both end. 236 */ 237 MGET(o, M_DONTWAIT, m->m_type); 238 if (o && len > MLEN) { 239 MCLGET(o, M_DONTWAIT); 240 if ((o->m_flags & M_EXT) == 0) { 241 m_free(o); 242 o = NULL; 243 } 244 } 245 if (!o) { 246 m_freem(m); 247 return NULL; /* ENOBUFS */ 248 } 249 /* get hlen from <n, off> into <o, 0> */ 250 o->m_len = hlen; 251 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 252 n->m_len -= hlen; 253 /* get tlen from <n->m_next, 0> into <o, hlen> */ 254 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 255 o->m_len += tlen; 256 m_adj(n->m_next, tlen); 257 o->m_next = n->m_next; 258 n->m_next = o; 259 n = o; 260 off = 0; 261 262 ok: 263 #ifdef PULLDOWN_DEBUG 264 { 265 struct mbuf *t; 266 printf("after:"); 267 for (t = m; t; t = t->m_next) 268 printf("%c%d", t == n ? '*' : ' ', t->m_len); 269 printf(" (off=%d)\n", off); 270 } 271 #endif 272 if (offp) 273 *offp = off; 274 return n; 275 } 276 277 static struct mbuf * 278 m_dup1(struct mbuf *m, int off, int len, int wait) 279 { 280 struct mbuf *n; 281 int l; 282 int copyhdr; 283 284 if (len > MCLBYTES) 285 return NULL; 286 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) { 287 copyhdr = 1; 288 MGETHDR(n, wait, m->m_type); 289 l = MHLEN; 290 } else { 291 copyhdr = 0; 292 MGET(n, wait, m->m_type); 293 l = MLEN; 294 } 295 if (n && len > l) { 296 MCLGET(n, wait); 297 if ((n->m_flags & M_EXT) == 0) { 298 m_free(n); 299 n = NULL; 300 } 301 } 302 if (!n) 303 return NULL; 304 305 if (copyhdr && !m_dup_pkthdr(n, m, wait)) { 306 m_free(n); 307 return NULL; 308 } 309 m_copydata(m, off, len, mtod(n, caddr_t)); 310 return n; 311 } 312 313 /* Get a packet tag structure along with specified data following. */ 314 struct m_tag * 315 m_tag_alloc(u_int32_t cookie, int type, int len, int wait) 316 { 317 struct m_tag *t; 318 319 if (len < 0) 320 return NULL; 321 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait); 322 if (t == NULL) 323 return NULL; 324 t->m_tag_id = type; 325 t->m_tag_len = len; 326 t->m_tag_cookie = cookie; 327 return t; 328 } 329 330 /* Free a packet tag. */ 331 void 332 m_tag_free(struct m_tag *t) 333 { 334 #ifdef MAC 335 if (t->m_tag_id == PACKET_TAG_MACLABEL) 336 mac_destroy_mbuf_tag(t); 337 #endif 338 free(t, M_PACKET_TAGS); 339 } 340 341 /* Prepend a packet tag. */ 342 void 343 m_tag_prepend(struct mbuf *m, struct m_tag *t) 344 { 345 KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t)); 346 SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link); 347 } 348 349 /* Unlink a packet tag. */ 350 void 351 m_tag_unlink(struct mbuf *m, struct m_tag *t) 352 { 353 KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t)); 354 SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link); 355 } 356 357 /* Unlink and free a packet tag. */ 358 void 359 m_tag_delete(struct mbuf *m, struct m_tag *t) 360 { 361 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); 362 m_tag_unlink(m, t); 363 m_tag_free(t); 364 } 365 366 /* Unlink and free a packet tag chain, starting from given tag. */ 367 void 368 m_tag_delete_chain(struct mbuf *m, struct m_tag *t) 369 { 370 struct m_tag *p, *q; 371 372 KASSERT(m, ("m_tag_delete_chain: null mbuf")); 373 if (t != NULL) 374 p = t; 375 else 376 p = SLIST_FIRST(&m->m_pkthdr.tags); 377 if (p == NULL) 378 return; 379 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) 380 m_tag_delete(m, q); 381 m_tag_delete(m, p); 382 } 383 384 /* Find a tag, starting from a given position. */ 385 struct m_tag * 386 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t) 387 { 388 struct m_tag *p; 389 390 KASSERT(m, ("m_tag_locate: null mbuf")); 391 if (t == NULL) 392 p = SLIST_FIRST(&m->m_pkthdr.tags); 393 else 394 p = SLIST_NEXT(t, m_tag_link); 395 while (p != NULL) { 396 if (p->m_tag_cookie == cookie && p->m_tag_id == type) 397 return p; 398 p = SLIST_NEXT(p, m_tag_link); 399 } 400 return NULL; 401 } 402 403 /* Copy a single tag. */ 404 struct m_tag * 405 m_tag_copy(struct m_tag *t, int how) 406 { 407 struct m_tag *p; 408 409 KASSERT(t, ("m_tag_copy: null tag")); 410 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); 411 if (p == NULL) 412 return (NULL); 413 #ifdef MAC 414 /* 415 * XXXMAC: we should probably pass off the initialization, and 416 * copying here? can we hide that PACKET_TAG_MACLABEL is 417 * special from the mbuf code? 418 */ 419 if (t->m_tag_id == PACKET_TAG_MACLABEL) { 420 if (mac_init_mbuf_tag(p, how) != 0) { 421 m_tag_free(p); 422 return (NULL); 423 } 424 mac_copy_mbuf_tag(t, p); 425 } else 426 #endif 427 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ 428 return p; 429 } 430 431 /* 432 * Copy two tag chains. The destination mbuf (to) loses any attached 433 * tags even if the operation fails. This should not be a problem, as 434 * m_tag_copy_chain() is typically called with a newly-allocated 435 * destination mbuf. 436 */ 437 int 438 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how) 439 { 440 struct m_tag *p, *t, *tprev = NULL; 441 442 KASSERT(to && from, 443 ("m_tag_copy_chain: null argument, to %p from %p", to, from)); 444 m_tag_delete_chain(to, NULL); 445 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) { 446 t = m_tag_copy(p, how); 447 if (t == NULL) { 448 m_tag_delete_chain(to, NULL); 449 return 0; 450 } 451 if (tprev == NULL) 452 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link); 453 else 454 SLIST_INSERT_AFTER(tprev, t, m_tag_link); 455 tprev = t; 456 } 457 return 1; 458 } 459 460 /* Initialize tags on an mbuf. */ 461 void 462 m_tag_init(struct mbuf *m) 463 { 464 SLIST_INIT(&m->m_pkthdr.tags); 465 } 466 467 /* Get first tag in chain. */ 468 struct m_tag * 469 m_tag_first(struct mbuf *m) 470 { 471 return SLIST_FIRST(&m->m_pkthdr.tags); 472 } 473 474 /* Get next tag in chain. */ 475 struct m_tag * 476 m_tag_next(struct mbuf *m, struct m_tag *t) 477 { 478 return SLIST_NEXT(t, m_tag_link); 479 } 480