1 /* $FreeBSD$ */ 2 /* $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $ */ 3 /* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */ 4 5 /* 6 * Copyright (C) 1999 WIDE Project. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the project nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 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. All advertising materials mentioning features or use of this software 47 * must display the following acknowledgement: 48 * This product includes software developed by the University of 49 * California, Berkeley and its contributors. 50 * 4. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95 67 */ 68 69 /*#define PULLDOWN_DEBUG*/ 70 71 #include "opt_mac.h" 72 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/kernel.h> 76 #include <sys/lock.h> 77 #include <sys/mac.h> 78 #include <sys/malloc.h> 79 #include <sys/mbuf.h> 80 #include <sys/mutex.h> 81 82 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information"); 83 84 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ 85 static struct mbuf *m_dup1(struct mbuf *, int, int, int); 86 87 /* 88 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 89 * packet chain before "off" is kept untouched. 90 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 91 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 92 * 93 * on error return (NULL return value), original "m" will be freed. 94 * 95 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 96 */ 97 struct mbuf * 98 m_pulldown(struct mbuf *m, int off, int len, int *offp) 99 { 100 struct mbuf *n, *o; 101 int hlen, tlen, olen; 102 int writable; 103 104 /* check invalid arguments. */ 105 if (m == NULL) 106 panic("m == NULL in m_pulldown()"); 107 if (len > MCLBYTES) { 108 m_freem(m); 109 return NULL; /* impossible */ 110 } 111 112 #ifdef PULLDOWN_DEBUG 113 { 114 struct mbuf *t; 115 printf("before:"); 116 for (t = m; t; t = t->m_next) 117 printf(" %d", t->m_len); 118 printf("\n"); 119 } 120 #endif 121 n = m; 122 while (n != NULL && off > 0) { 123 if (n->m_len > off) 124 break; 125 off -= n->m_len; 126 n = n->m_next; 127 } 128 /* be sure to point non-empty mbuf */ 129 while (n != NULL && n->m_len == 0) 130 n = n->m_next; 131 if (!n) { 132 m_freem(m); 133 return NULL; /* mbuf chain too short */ 134 } 135 136 /* 137 * XXX: This code is flawed because it considers a "writable" mbuf 138 * data region to require all of the following: 139 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 140 * mbuf, it is still not considered "writable." 141 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 142 * EXT_CLUSTER. Anything else makes it non-writable. 143 * (iii) M_WRITABLE() must evaluate true. 144 * Ideally, the requirement should only be (iii). 145 * 146 * If we're writable, we're sure we're writable, because the ref. count 147 * cannot increase from 1, as that would require posession of mbuf 148 * n by someone else (which is impossible). However, if we're _not_ 149 * writable, we may eventually become writable )if the ref. count drops 150 * to 1), but we'll fail to notice it unless we re-evaluate 151 * M_WRITABLE(). For now, we only evaluate once at the beginning and 152 * live with this. 153 */ 154 /* 155 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 156 * then we're not "writable," according to this code. 157 */ 158 writable = 0; 159 if ((n->m_flags & M_EXT) == 0 || 160 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) 161 writable = 1; 162 163 /* 164 * the target data is on <n, off>. 165 * if we got enough data on the mbuf "n", we're done. 166 */ 167 if ((off == 0 || offp) && len <= n->m_len - off && writable) 168 goto ok; 169 170 /* 171 * when len <= n->m_len - off and off != 0, it is a special case. 172 * len bytes from <n, off> sits in single mbuf, but the caller does 173 * not like the starting position (off). 174 * chop the current mbuf into two pieces, set off to 0. 175 */ 176 if (len <= n->m_len - off) { 177 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT); 178 if (o == NULL) { 179 m_freem(m); 180 return NULL; /* ENOBUFS */ 181 } 182 n->m_len = off; 183 o->m_next = n->m_next; 184 n->m_next = o; 185 n = n->m_next; 186 off = 0; 187 goto ok; 188 } 189 190 /* 191 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 192 * and construct contiguous mbuf with m_len == len. 193 * note that hlen + tlen == len, and tlen > 0. 194 */ 195 hlen = n->m_len - off; 196 tlen = len - hlen; 197 198 /* 199 * ensure that we have enough trailing data on mbuf chain. 200 * if not, we can do nothing about the chain. 201 */ 202 olen = 0; 203 for (o = n->m_next; o != NULL; o = o->m_next) 204 olen += o->m_len; 205 if (hlen + olen < len) { 206 m_freem(m); 207 return NULL; /* mbuf chain too short */ 208 } 209 210 /* 211 * easy cases first. 212 * we need to use m_copydata() to get data from <n->m_next, 0>. 213 */ 214 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 215 && writable) { 216 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 217 n->m_len += tlen; 218 m_adj(n->m_next, tlen); 219 goto ok; 220 } 221 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 222 && writable) { 223 n->m_next->m_data -= hlen; 224 n->m_next->m_len += hlen; 225 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 226 n->m_len -= hlen; 227 n = n->m_next; 228 off = 0; 229 goto ok; 230 } 231 232 /* 233 * now, we need to do the hard way. don't m_copy as there's no room 234 * on both end. 235 */ 236 MGET(o, M_DONTWAIT, m->m_type); 237 if (o && len > MLEN) { 238 MCLGET(o, M_DONTWAIT); 239 if ((o->m_flags & M_EXT) == 0) { 240 m_free(o); 241 o = NULL; 242 } 243 } 244 if (!o) { 245 m_freem(m); 246 return NULL; /* ENOBUFS */ 247 } 248 /* get hlen from <n, off> into <o, 0> */ 249 o->m_len = hlen; 250 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 251 n->m_len -= hlen; 252 /* get tlen from <n->m_next, 0> into <o, hlen> */ 253 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 254 o->m_len += tlen; 255 m_adj(n->m_next, tlen); 256 o->m_next = n->m_next; 257 n->m_next = o; 258 n = o; 259 off = 0; 260 261 ok: 262 #ifdef PULLDOWN_DEBUG 263 { 264 struct mbuf *t; 265 printf("after:"); 266 for (t = m; t; t = t->m_next) 267 printf("%c%d", t == n ? '*' : ' ', t->m_len); 268 printf(" (off=%d)\n", off); 269 } 270 #endif 271 if (offp) 272 *offp = off; 273 return n; 274 } 275 276 static struct mbuf * 277 m_dup1(struct mbuf *m, int off, int len, int wait) 278 { 279 struct mbuf *n; 280 int l; 281 int copyhdr; 282 283 if (len > MCLBYTES) 284 return NULL; 285 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) { 286 copyhdr = 1; 287 MGETHDR(n, wait, m->m_type); 288 l = MHLEN; 289 } else { 290 copyhdr = 0; 291 MGET(n, wait, m->m_type); 292 l = MLEN; 293 } 294 if (n && len > l) { 295 MCLGET(n, wait); 296 if ((n->m_flags & M_EXT) == 0) { 297 m_free(n); 298 n = NULL; 299 } 300 } 301 if (!n) 302 return NULL; 303 304 if (copyhdr && !m_dup_pkthdr(n, m, wait)) { 305 m_free(n); 306 return NULL; 307 } 308 m_copydata(m, off, len, mtod(n, caddr_t)); 309 return n; 310 } 311 312 /* Get a packet tag structure along with specified data following. */ 313 struct m_tag * 314 m_tag_alloc(u_int32_t cookie, int type, int len, int wait) 315 { 316 struct m_tag *t; 317 318 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 t->m_tag_id = type; 324 t->m_tag_len = len; 325 t->m_tag_cookie = cookie; 326 return t; 327 } 328 329 /* Free a packet tag. */ 330 void 331 m_tag_free(struct m_tag *t) 332 { 333 #ifdef MAC 334 if (t->m_tag_id == PACKET_TAG_MACLABEL) 335 mac_destroy_mbuf_tag(t); 336 #endif 337 free(t, M_PACKET_TAGS); 338 } 339 340 /* Prepend a packet tag. */ 341 void 342 m_tag_prepend(struct mbuf *m, struct m_tag *t) 343 { 344 KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t)); 345 SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link); 346 } 347 348 /* Unlink a packet tag. */ 349 void 350 m_tag_unlink(struct mbuf *m, struct m_tag *t) 351 { 352 KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t)); 353 SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link); 354 } 355 356 /* Unlink and free a packet tag. */ 357 void 358 m_tag_delete(struct mbuf *m, struct m_tag *t) 359 { 360 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); 361 m_tag_unlink(m, t); 362 m_tag_free(t); 363 } 364 365 /* Unlink and free a packet tag chain, starting from given tag. */ 366 void 367 m_tag_delete_chain(struct mbuf *m, struct m_tag *t) 368 { 369 struct m_tag *p, *q; 370 371 KASSERT(m, ("m_tag_delete_chain: null mbuf")); 372 if (t != NULL) 373 p = t; 374 else 375 p = SLIST_FIRST(&m->m_pkthdr.tags); 376 if (p == NULL) 377 return; 378 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) 379 m_tag_delete(m, q); 380 m_tag_delete(m, p); 381 } 382 383 /* Find a tag, starting from a given position. */ 384 struct m_tag * 385 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t) 386 { 387 struct m_tag *p; 388 389 KASSERT(m, ("m_tag_locate: null mbuf")); 390 if (t == NULL) 391 p = SLIST_FIRST(&m->m_pkthdr.tags); 392 else 393 p = SLIST_NEXT(t, m_tag_link); 394 while (p != NULL) { 395 if (p->m_tag_cookie == cookie && p->m_tag_id == type) 396 return p; 397 p = SLIST_NEXT(p, m_tag_link); 398 } 399 return NULL; 400 } 401 402 /* Copy a single tag. */ 403 struct m_tag * 404 m_tag_copy(struct m_tag *t, int how) 405 { 406 struct m_tag *p; 407 408 KASSERT(t, ("m_tag_copy: null tag")); 409 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); 410 if (p == NULL) 411 return (NULL); 412 #ifdef MAC 413 /* 414 * XXXMAC: we should probably pass off the initialization, and 415 * copying here? can we hide that PACKET_TAG_MACLABEL is 416 * special from the mbuf code? 417 */ 418 if (t->m_tag_id == PACKET_TAG_MACLABEL) { 419 if (mac_init_mbuf_tag(p, how) != 0) { 420 m_tag_free(p); 421 return (NULL); 422 } 423 mac_copy_mbuf_tag(t, p); 424 } else 425 #endif 426 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ 427 return p; 428 } 429 430 /* 431 * Copy two tag chains. The destination mbuf (to) loses any attached 432 * tags even if the operation fails. This should not be a problem, as 433 * m_tag_copy_chain() is typically called with a newly-allocated 434 * destination mbuf. 435 */ 436 int 437 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how) 438 { 439 struct m_tag *p, *t, *tprev = NULL; 440 441 KASSERT(to && from, 442 ("m_tag_copy_chain: null argument, to %p from %p", to, from)); 443 m_tag_delete_chain(to, NULL); 444 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) { 445 t = m_tag_copy(p, how); 446 if (t == NULL) { 447 m_tag_delete_chain(to, NULL); 448 return 0; 449 } 450 if (tprev == NULL) 451 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link); 452 else 453 SLIST_INSERT_AFTER(tprev, t, m_tag_link); 454 tprev = t; 455 } 456 return 1; 457 } 458 459 /* Initialize tags on an mbuf. */ 460 void 461 m_tag_init(struct mbuf *m) 462 { 463 SLIST_INIT(&m->m_pkthdr.tags); 464 } 465 466 /* Get first tag in chain. */ 467 struct m_tag * 468 m_tag_first(struct mbuf *m) 469 { 470 return SLIST_FIRST(&m->m_pkthdr.tags); 471 } 472 473 /* Get next tag in chain. */ 474 struct m_tag * 475 m_tag_next(struct mbuf *m, struct m_tag *t) 476 { 477 return SLIST_NEXT(t, m_tag_link); 478 } 479