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 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information"); 80 81 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */ 82 static struct mbuf *m_dup1(struct mbuf *, int, int, int); 83 84 /* 85 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 86 * packet chain before "off" is kept untouched. 87 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 88 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 89 * 90 * on error return (NULL return value), original "m" will be freed. 91 * 92 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 93 */ 94 struct mbuf * 95 m_pulldown(struct mbuf *m, int off, int len, int *offp) 96 { 97 struct mbuf *n, *o; 98 int hlen, tlen, olen; 99 int writable; 100 101 /* check invalid arguments. */ 102 if (m == NULL) 103 panic("m == NULL in m_pulldown()"); 104 if (len > MCLBYTES) { 105 m_freem(m); 106 return NULL; /* impossible */ 107 } 108 109 #ifdef PULLDOWN_DEBUG 110 { 111 struct mbuf *t; 112 printf("before:"); 113 for (t = m; t; t = t->m_next) 114 printf(" %d", t->m_len); 115 printf("\n"); 116 } 117 #endif 118 n = m; 119 while (n != NULL && off > 0) { 120 if (n->m_len > off) 121 break; 122 off -= n->m_len; 123 n = n->m_next; 124 } 125 /* be sure to point non-empty mbuf */ 126 while (n != NULL && n->m_len == 0) 127 n = n->m_next; 128 if (!n) { 129 m_freem(m); 130 return NULL; /* mbuf chain too short */ 131 } 132 133 /* 134 * XXX: This code is flawed because it considers a "writable" mbuf 135 * data region to require all of the following: 136 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 137 * mbuf, it is still not considered "writable." 138 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 139 * EXT_CLUSTER. Anything else makes it non-writable. 140 * (iii) M_WRITABLE() must evaluate true. 141 * Ideally, the requirement should only be (iii). 142 * 143 * If we're writable, we're sure we're writable, because the ref. count 144 * cannot increase from 1, as that would require posession of mbuf 145 * n by someone else (which is impossible). However, if we're _not_ 146 * writable, we may eventually become writable )if the ref. count drops 147 * to 1), but we'll fail to notice it unless we re-evaluate 148 * M_WRITABLE(). For now, we only evaluate once at the beginning and 149 * live with this. 150 */ 151 /* 152 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 153 * then we're not "writable," according to this code. 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 && writable) 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_DONTWAIT); 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) { 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 MGET(o, M_DONTWAIT, m->m_type); 234 if (o && len > MLEN) { 235 MCLGET(o, M_DONTWAIT); 236 if ((o->m_flags & M_EXT) == 0) { 237 m_free(o); 238 o = NULL; 239 } 240 } 241 if (!o) { 242 m_freem(m); 243 return NULL; /* ENOBUFS */ 244 } 245 /* get hlen from <n, off> into <o, 0> */ 246 o->m_len = hlen; 247 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 248 n->m_len -= hlen; 249 /* get tlen from <n->m_next, 0> into <o, hlen> */ 250 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 251 o->m_len += tlen; 252 m_adj(n->m_next, tlen); 253 o->m_next = n->m_next; 254 n->m_next = o; 255 n = o; 256 off = 0; 257 258 ok: 259 #ifdef PULLDOWN_DEBUG 260 { 261 struct mbuf *t; 262 printf("after:"); 263 for (t = m; t; t = t->m_next) 264 printf("%c%d", t == n ? '*' : ' ', t->m_len); 265 printf(" (off=%d)\n", off); 266 } 267 #endif 268 if (offp) 269 *offp = off; 270 return n; 271 } 272 273 static struct mbuf * 274 m_dup1(struct mbuf *m, int off, int len, int wait) 275 { 276 struct mbuf *n; 277 int l; 278 int copyhdr; 279 280 if (len > MCLBYTES) 281 return NULL; 282 if (off == 0 && (m->m_flags & M_PKTHDR) != 0) { 283 copyhdr = 1; 284 MGETHDR(n, wait, m->m_type); 285 l = MHLEN; 286 } else { 287 copyhdr = 0; 288 MGET(n, wait, m->m_type); 289 l = MLEN; 290 } 291 if (n && len > l) { 292 MCLGET(n, wait); 293 if ((n->m_flags & M_EXT) == 0) { 294 m_free(n); 295 n = NULL; 296 } 297 } 298 if (!n) 299 return NULL; 300 301 if (copyhdr && !m_dup_pkthdr(n, m, wait)) { 302 m_free(n); 303 return NULL; 304 } 305 m_copydata(m, off, len, mtod(n, caddr_t)); 306 n->m_len = len; 307 return n; 308 } 309 310 /* Free a packet tag. */ 311 static void 312 _m_tag_free(struct m_tag *t) 313 { 314 #ifdef MAC 315 if (t->m_tag_id == PACKET_TAG_MACLABEL) 316 mac_destroy_mbuf_tag(t); 317 #endif 318 free(t, M_PACKET_TAGS); 319 } 320 321 /* Get a packet tag structure along with specified data following. */ 322 struct m_tag * 323 m_tag_alloc(u_int32_t cookie, int type, int len, int wait) 324 { 325 struct m_tag *t; 326 327 if (len < 0) 328 return NULL; 329 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait); 330 if (t == NULL) 331 return NULL; 332 m_tag_setup(t, cookie, type, len); 333 t->m_tag_free = _m_tag_free; 334 return t; 335 } 336 337 /* Unlink and free a packet tag. */ 338 void 339 m_tag_delete(struct mbuf *m, struct m_tag *t) 340 { 341 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t)); 342 m_tag_unlink(m, t); 343 m_tag_free(t); 344 } 345 346 /* Unlink and free a packet tag chain, starting from given tag. */ 347 void 348 m_tag_delete_chain(struct mbuf *m, struct m_tag *t) 349 { 350 struct m_tag *p, *q; 351 352 KASSERT(m, ("m_tag_delete_chain: null mbuf")); 353 if (t != NULL) 354 p = t; 355 else 356 p = SLIST_FIRST(&m->m_pkthdr.tags); 357 if (p == NULL) 358 return; 359 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL) 360 m_tag_delete(m, q); 361 m_tag_delete(m, p); 362 } 363 364 /* 365 * Strip off all tags that would normally vanish when 366 * passing through a network interface. Only persistent 367 * tags will exist after this; these are expected to remain 368 * so long as the mbuf chain exists, regardless of the 369 * path the mbufs take. 370 */ 371 void 372 m_tag_delete_nonpersistent(struct mbuf *m) 373 { 374 struct m_tag *p, *q; 375 376 SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q) 377 if ((p->m_tag_id & MTAG_PERSISTENT) == 0) 378 m_tag_delete(m, p); 379 } 380 381 /* Find a tag, starting from a given position. */ 382 struct m_tag * 383 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t) 384 { 385 struct m_tag *p; 386 387 KASSERT(m, ("m_tag_locate: null mbuf")); 388 if (t == NULL) 389 p = SLIST_FIRST(&m->m_pkthdr.tags); 390 else 391 p = SLIST_NEXT(t, m_tag_link); 392 while (p != NULL) { 393 if (p->m_tag_cookie == cookie && p->m_tag_id == type) 394 return p; 395 p = SLIST_NEXT(p, m_tag_link); 396 } 397 return NULL; 398 } 399 400 /* Copy a single tag. */ 401 struct m_tag * 402 m_tag_copy(struct m_tag *t, int how) 403 { 404 struct m_tag *p; 405 406 KASSERT(t, ("m_tag_copy: null tag")); 407 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how); 408 if (p == NULL) 409 return (NULL); 410 #ifdef MAC 411 /* 412 * XXXMAC: we should probably pass off the initialization, and 413 * copying here? can we hide that PACKET_TAG_MACLABEL is 414 * special from the mbuf code? 415 */ 416 if (t->m_tag_id == PACKET_TAG_MACLABEL) { 417 if (mac_init_mbuf_tag(p, how) != 0) { 418 m_tag_free(p); 419 return (NULL); 420 } 421 mac_copy_mbuf_tag(t, p); 422 } else 423 #endif 424 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */ 425 return p; 426 } 427 428 /* 429 * Copy two tag chains. The destination mbuf (to) loses any attached 430 * tags even if the operation fails. This should not be a problem, as 431 * m_tag_copy_chain() is typically called with a newly-allocated 432 * destination mbuf. 433 */ 434 int 435 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how) 436 { 437 struct m_tag *p, *t, *tprev = NULL; 438 439 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