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("$FreeBSD$"); 65 66 /*#define PULLDOWN_DEBUG*/ 67 68 #include "opt_mac.h" 69 70 #include <sys/param.h> 71 #include <sys/systm.h> 72 #include <sys/kernel.h> 73 #include <sys/lock.h> 74 #include <sys/mac.h> 75 #include <sys/malloc.h> 76 #include <sys/mbuf.h> 77 #include <sys/mutex.h> 78 79 static MALLOC_DEFINE(M_PACKET_TAGS, MBUF_TAG_MEM_NAME, 80 "packet-attached information"); 81 82 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ 83 static struct mbuf *m_dup1(struct mbuf *, int, int, int); 84 85 /* 86 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 87 * packet chain before "off" is kept untouched. 88 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 89 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 90 * 91 * on error return (NULL return value), original "m" will be freed. 92 * 93 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 94 */ 95 struct mbuf * 96 m_pulldown(struct mbuf *m, int off, int len, int *offp) 97 { 98 struct mbuf *n, *o; 99 int hlen, tlen, olen; 100 int writable; 101 102 /* check invalid arguments. */ 103 if (m == NULL) 104 panic("m == NULL in m_pulldown()"); 105 if (len > MCLBYTES) { 106 m_freem(m); 107 return NULL; /* impossible */ 108 } 109 110 #ifdef PULLDOWN_DEBUG 111 { 112 struct mbuf *t; 113 printf("before:"); 114 for (t = m; t; t = t->m_next) 115 printf(" %d", t->m_len); 116 printf("\n"); 117 } 118 #endif 119 n = m; 120 while (n != NULL && off > 0) { 121 if (n->m_len > off) 122 break; 123 off -= n->m_len; 124 n = n->m_next; 125 } 126 /* be sure to point non-empty mbuf */ 127 while (n != NULL && n->m_len == 0) 128 n = n->m_next; 129 if (!n) { 130 m_freem(m); 131 return NULL; /* mbuf chain too short */ 132 } 133 134 /* 135 * XXX: This code is flawed because it considers a "writable" mbuf 136 * data region to require all of the following: 137 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 138 * mbuf, it is still not considered "writable." 139 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 140 * EXT_CLUSTER. Anything else makes it non-writable. 141 * (iii) M_WRITABLE() must evaluate true. 142 * Ideally, the requirement should only be (iii). 143 * 144 * If we're writable, we're sure we're writable, because the ref. count 145 * cannot increase from 1, as that would require posession of mbuf 146 * n by someone else (which is impossible). However, if we're _not_ 147 * writable, we may eventually become writable )if the ref. count drops 148 * to 1), but we'll fail to notice it unless we re-evaluate 149 * M_WRITABLE(). For now, we only evaluate once at the beginning and 150 * live with this. 151 */ 152 /* 153 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 154 * then we're not "writable," according to this code. 155 */ 156 writable = 0; 157 if ((n->m_flags & M_EXT) == 0 || 158 (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n))) 159 writable = 1; 160 161 /* 162 * the target data is on <n, off>. 163 * if we got enough data on the mbuf "n", we're done. 164 */ 165 if ((off == 0 || offp) && len <= n->m_len - off && writable) 166 goto ok; 167 168 /* 169 * when len <= n->m_len - off and off != 0, it is a special case. 170 * len bytes from <n, off> sits in single mbuf, but the caller does 171 * not like the starting position (off). 172 * chop the current mbuf into two pieces, set off to 0. 173 */ 174 if (len <= n->m_len - off) { 175 o = m_dup1(n, off, n->m_len - off, M_DONTWAIT); 176 if (o == NULL) { 177 m_freem(m); 178 return NULL; /* ENOBUFS */ 179 } 180 n->m_len = off; 181 o->m_next = n->m_next; 182 n->m_next = o; 183 n = n->m_next; 184 off = 0; 185 goto ok; 186 } 187 188 /* 189 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 190 * and construct contiguous mbuf with m_len == len. 191 * note that hlen + tlen == len, and tlen > 0. 192 */ 193 hlen = n->m_len - off; 194 tlen = len - hlen; 195 196 /* 197 * ensure that we have enough trailing data on mbuf chain. 198 * if not, we can do nothing about the chain. 199 */ 200 olen = 0; 201 for (o = n->m_next; o != NULL; o = o->m_next) 202 olen += o->m_len; 203 if (hlen + olen < len) { 204 m_freem(m); 205 return NULL; /* mbuf chain too short */ 206 } 207 208 /* 209 * easy cases first. 210 * we need to use m_copydata() to get data from <n->m_next, 0>. 211 */ 212 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 213 && writable) { 214 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 215 n->m_len += tlen; 216 m_adj(n->m_next, tlen); 217 goto ok; 218 } 219 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 220 && writable) { 221 n->m_next->m_data -= hlen; 222 n->m_next->m_len += hlen; 223 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 224 n->m_len -= hlen; 225 n = n->m_next; 226 off = 0; 227 goto ok; 228 } 229 230 /* 231 * now, we need to do the hard way. don't m_copy as there's no room 232 * on both end. 233 */ 234 if (len > MLEN) 235 o = m_getcl(M_DONTWAIT, m->m_type, 0); 236 else 237 o = m_get(M_DONTWAIT, m->m_type); 238 if (!o) { 239 m_freem(m); 240 return NULL; /* ENOBUFS */ 241 } 242 /* get hlen from <n, off> into <o, 0> */ 243 o->m_len = hlen; 244 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 245 n->m_len -= hlen; 246 /* get tlen from <n->m_next, 0> into <o, hlen> */ 247 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 248 o->m_len += tlen; 249 m_adj(n->m_next, tlen); 250 o->m_next = n->m_next; 251 n->m_next = o; 252 n = o; 253 off = 0; 254 255 ok: 256 #ifdef PULLDOWN_DEBUG 257 { 258 struct mbuf *t; 259 printf("after:"); 260 for (t = m; t; t = t->m_next) 261 printf("%c%d", t == n ? '*' : ' ', t->m_len); 262 printf(" (off=%d)\n", off); 263 } 264 #endif 265 if (offp) 266 *offp = off; 267 return n; 268 } 269 270 static struct mbuf * 271 m_dup1(struct mbuf *m, int off, int len, int wait) 272 { 273 struct mbuf *n; 274 int copyhdr; 275 276 if (len > MCLBYTES) 277 return NULL; 278 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) 279 copyhdr = 1; 280 else 281 copyhdr = 0; 282 if (len >= MINCLSIZE) { 283 if (copyhdr == 1) 284 n = m_getcl(wait, m->m_type, M_PKTHDR); 285 else 286 n = m_getcl(wait, m->m_type, 0); 287 } else { 288 if (copyhdr == 1) 289 n = m_gethdr(wait, m->m_type); 290 else 291 n = m_get(wait, m->m_type); 292 } 293 if (!n) 294 return NULL; /* ENOBUFS */ 295 296 if (copyhdr && !m_dup_pkthdr(n, m, wait)) { 297 m_free(n); 298 return NULL; 299 } 300 m_copydata(m, off, len, mtod(n, caddr_t)); 301 n->m_len = len; 302 return n; 303 } 304 305 /* Free a packet tag. */ 306 void 307 m_tag_free_default(struct m_tag *t) 308 { 309 #ifdef MAC 310 if (t->m_tag_id == PACKET_TAG_MACLABEL) 311 mac_destroy_mbuf_tag(t); 312 #endif 313 free(t, M_PACKET_TAGS); 314 } 315 316 /* Get a packet tag structure along with specified data following. */ 317 struct m_tag * 318 m_tag_alloc(u_int32_t cookie, int type, int len, int wait) 319 { 320 struct m_tag *t; 321 322 MBUF_CHECKSLEEP(wait); 323 if (len < 0) 324 return NULL; 325 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait); 326 if (t == NULL) 327 return NULL; 328 m_tag_setup(t, cookie, type, len); 329 t->m_tag_free = m_tag_free_default; 330 return t; 331 } 332 333 /* Unlink and free a packet tag. */ 334 void 335 m_tag_delete(struct mbuf *m, struct m_tag *t) 336 { 337 338 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); 339 m_tag_unlink(m, t); 340 m_tag_free(t); 341 } 342 343 /* Unlink and free a packet tag chain, starting from given tag. */ 344 void 345 m_tag_delete_chain(struct mbuf *m, struct m_tag *t) 346 { 347 struct m_tag *p, *q; 348 349 KASSERT(m, ("m_tag_delete_chain: null mbuf")); 350 if (t != NULL) 351 p = t; 352 else 353 p = SLIST_FIRST(&m->m_pkthdr.tags); 354 if (p == NULL) 355 return; 356 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) 357 m_tag_delete(m, q); 358 m_tag_delete(m, p); 359 } 360 361 /* 362 * Strip off all tags that would normally vanish when 363 * passing through a network interface. Only persistent 364 * tags will exist after this; these are expected to remain 365 * so long as the mbuf chain exists, regardless of the 366 * path the mbufs take. 367 */ 368 void 369 m_tag_delete_nonpersistent(struct mbuf *m) 370 { 371 struct m_tag *p, *q; 372 373 SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q) 374 if ((p->m_tag_id & MTAG_PERSISTENT) == 0) 375 m_tag_delete(m, p); 376 } 377 378 /* Find a tag, starting from a given position. */ 379 struct m_tag * 380 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t) 381 { 382 struct m_tag *p; 383 384 KASSERT(m, ("m_tag_locate: null mbuf")); 385 if (t == NULL) 386 p = SLIST_FIRST(&m->m_pkthdr.tags); 387 else 388 p = SLIST_NEXT(t, m_tag_link); 389 while (p != NULL) { 390 if (p->m_tag_cookie == cookie && p->m_tag_id == type) 391 return p; 392 p = SLIST_NEXT(p, m_tag_link); 393 } 394 return NULL; 395 } 396 397 /* Copy a single tag. */ 398 struct m_tag * 399 m_tag_copy(struct m_tag *t, int how) 400 { 401 struct m_tag *p; 402 403 MBUF_CHECKSLEEP(how); 404 KASSERT(t, ("m_tag_copy: null tag")); 405 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); 406 if (p == NULL) 407 return (NULL); 408 #ifdef MAC 409 /* 410 * XXXMAC: we should probably pass off the initialization, and 411 * copying here? can we hide that PACKET_TAG_MACLABEL is 412 * special from the mbuf code? 413 */ 414 if (t->m_tag_id == PACKET_TAG_MACLABEL) { 415 if (mac_init_mbuf_tag(p, how) != 0) { 416 m_tag_free(p); 417 return (NULL); 418 } 419 mac_copy_mbuf_tag(t, p); 420 } else 421 #endif 422 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ 423 return p; 424 } 425 426 /* 427 * Copy two tag chains. The destination mbuf (to) loses any attached 428 * tags even if the operation fails. This should not be a problem, as 429 * m_tag_copy_chain() is typically called with a newly-allocated 430 * destination mbuf. 431 */ 432 int 433 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how) 434 { 435 struct m_tag *p, *t, *tprev = NULL; 436 437 MBUF_CHECKSLEEP(how); 438 KASSERT(to && from, 439 ("m_tag_copy_chain: null argument, to %p from %p", to, from)); 440 m_tag_delete_chain(to, NULL); 441 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) { 442 t = m_tag_copy(p, how); 443 if (t == NULL) { 444 m_tag_delete_chain(to, NULL); 445 return 0; 446 } 447 if (tprev == NULL) 448 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link); 449 else 450 SLIST_INSERT_AFTER(tprev, t, m_tag_link); 451 tprev = t; 452 } 453 return 1; 454 } 455