1 /* $NetBSD: ipsec_mbuf.c,v 1.6 2005/02/26 22:45:13 perry Exp $ */
2 /*-
3 * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD: /repoman/r/ncvs/src/sys/netipsec/ipsec_mbuf.c,v 1.5.2.2 2003/03/28 20:32:53 sam Exp $
28 */
29
30 #include <sys/cdefs.h>
31 __KERNEL_RCSID(0, "$NetBSD: ipsec_mbuf.c,v 1.6 2005/02/26 22:45:13 perry Exp $");
32
33 /*
34 * IPsec-specific mbuf routines.
35 */
36
37 #ifdef __FreeBSD__
38 #include "opt_param.h"
39 #endif
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/mbuf.h>
44 #include <sys/socket.h>
45
46 #include <net/route.h>
47 #include <netinet/in.h>
48
49 #include <netipsec/ipsec.h>
50 #include <netipsec/ipsec_var.h>
51
52 #include <netipsec/ipsec_osdep.h>
53 #include <net/net_osdep.h>
54
55 extern struct mbuf *m_getptr(struct mbuf *, int, int *);
56
57 /*
58 * Create a writable copy of the mbuf chain. While doing this
59 * we compact the chain with a goal of producing a chain with
60 * at most two mbufs. The second mbuf in this chain is likely
61 * to be a cluster. The primary purpose of this work is to create
62 * a writable packet for encryption, compression, etc. The
63 * secondary goal is to linearize the data so the data can be
64 * passed to crypto hardware in the most efficient manner possible.
65 */
66 struct mbuf *
67 m_clone(struct mbuf *m0)
68 {
69 struct mbuf *m, *mprev;
70 struct mbuf *n, *mfirst, *mlast;
71 int len, off;
72
73 IPSEC_ASSERT(m0 != NULL, ("m_clone: null mbuf"));
74
75 mprev = NULL;
76 for (m = m0; m != NULL; m = mprev->m_next) {
77 /*
78 * Regular mbufs are ignored unless there's a cluster
79 * in front of it that we can use to coalesce. We do
80 * the latter mainly so later clusters can be coalesced
81 * also w/o having to handle them specially (i.e. convert
82 * mbuf+cluster -> cluster). This optimization is heavily
83 * influenced by the assumption that we're running over
84 * Ethernet where MCLBYTES is large enough that the max
85 * packet size will permit lots of coalescing into a
86 * single cluster. This in turn permits efficient
87 * crypto operations, especially when using hardware.
88 */
89 if ((m->m_flags & M_EXT) == 0) {
90 if (mprev && (mprev->m_flags & M_EXT) &&
91 m->m_len <= M_TRAILINGSPACE(mprev)) {
92 /* XXX: this ignores mbuf types */
93 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
94 mtod(m, caddr_t), m->m_len);
95 mprev->m_len += m->m_len;
96 mprev->m_next = m->m_next; /* unlink from chain */
97 m_free(m); /* reclaim mbuf */
98 newipsecstat.ips_mbcoalesced++;
99 } else {
100 mprev = m;
101 }
102 continue;
103 }
104 /*
105 * Writable mbufs are left alone (for now). Note
106 * that for 4.x systems it's not possible to identify
107 * whether or not mbufs with external buffers are
108 * writable unless they use clusters.
109 */
110 if (M_EXT_WRITABLE(m)) {
111 mprev = m;
112 continue;
113 }
114
115 /*
116 * Not writable, replace with a copy or coalesce with
117 * the previous mbuf if possible (since we have to copy
118 * it anyway, we try to reduce the number of mbufs and
119 * clusters so that future work is easier).
120 */
121 IPSEC_ASSERT(m->m_flags & M_EXT,
122 ("m_clone: m_flags 0x%x", m->m_flags));
123 /* NB: we only coalesce into a cluster or larger */
124 if (mprev != NULL && (mprev->m_flags & M_EXT) &&
125 m->m_len <= M_TRAILINGSPACE(mprev)) {
126 /* XXX: this ignores mbuf types */
127 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
128 mtod(m, caddr_t), m->m_len);
129 mprev->m_len += m->m_len;
130 mprev->m_next = m->m_next; /* unlink from chain */
131 m_free(m); /* reclaim mbuf */
132 newipsecstat.ips_clcoalesced++;
133 continue;
134 }
135
136 /*
137 * Allocate new space to hold the copy...
138 */
139 /* XXX why can M_PKTHDR be set past the first mbuf? */
140 if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
141 /*
142 * NB: if a packet header is present we must
143 * allocate the mbuf separately from any cluster
144 * because M_MOVE_PKTHDR will smash the data
145 * pointer and drop the M_EXT marker.
146 */
147 MGETHDR(n, M_DONTWAIT, m->m_type);
148 if (n == NULL) {
149 m_freem(m0);
150 return (NULL);
151 }
152 M_MOVE_PKTHDR(n, m);
153 MCLGET(n, M_DONTWAIT);
154 if ((n->m_flags & M_EXT) == 0) {
155 m_free(n);
156 m_freem(m0);
157 return (NULL);
158 }
159 } else {
160 n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
161 if (n == NULL) {
162 m_freem(m0);
163 return (NULL);
164 }
165 }
166 /*
167 * ... and copy the data. We deal with jumbo mbufs
168 * (i.e. m_len > MCLBYTES) by splitting them into
169 * clusters. We could just malloc a buffer and make
170 * it external but too many device drivers don't know
171 * how to break up the non-contiguous memory when
172 * doing DMA.
173 */
174 len = m->m_len;
175 off = 0;
176 mfirst = n;
177 mlast = NULL;
178 for (;;) {
179 int cc = min(len, MCLBYTES);
180 memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
181 n->m_len = cc;
182 if (mlast != NULL)
183 mlast->m_next = n;
184 mlast = n;
185 newipsecstat.ips_clcopied++;
186
187 len -= cc;
188 if (len <= 0)
189 break;
190 off += cc;
191
192 n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
193 if (n == NULL) {
194 m_freem(mfirst);
195 m_freem(m0);
196 return (NULL);
197 }
198 }
199 n->m_next = m->m_next;
200 if (mprev == NULL)
201 m0 = mfirst; /* new head of chain */
202 else
203 mprev->m_next = mfirst; /* replace old mbuf */
204 m_free(m); /* release old mbuf */
205 mprev = mfirst;
206 }
207 return (m0);
208 }
209
210 /*
211 * Make space for a new header of length hlen at skip bytes
212 * into the packet. When doing this we allocate new mbufs only
213 * when absolutely necessary. The mbuf where the new header
214 * is to go is returned together with an offset into the mbuf.
215 * If NULL is returned then the mbuf chain may have been modified;
216 * the caller is assumed to always free the chain.
217 */
218 struct mbuf *
219 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
220 {
221 struct mbuf *m;
222 unsigned remain;
223
224 IPSEC_ASSERT(m0 != NULL, ("m_dmakespace: null mbuf"));
225 IPSEC_ASSERT(hlen < MHLEN, ("m_makespace: hlen too big: %u", hlen));
226
227 for (m = m0; m && skip > m->m_len; m = m->m_next)
228 skip -= m->m_len;
229 if (m == NULL)
230 return (NULL);
231 /*
232 * At this point skip is the offset into the mbuf m
233 * where the new header should be placed. Figure out
234 * if there's space to insert the new header. If so,
235 * and copying the remainder makese sense then do so.
236 * Otherwise insert a new mbuf in the chain, splitting
237 * the contents of m as needed.
238 */
239 remain = m->m_len - skip; /* data to move */
240 if (hlen > M_TRAILINGSPACE(m)) {
241 struct mbuf *n;
242
243 /* XXX code doesn't handle clusters XXX */
244 IPSEC_ASSERT(remain < MLEN,
245 ("m_makespace: remainder too big: %u", remain));
246 /*
247 * Not enough space in m, split the contents
248 * of m, inserting new mbufs as required.
249 *
250 * NB: this ignores mbuf types.
251 */
252 MGET(n, M_DONTWAIT, MT_DATA);
253 if (n == NULL)
254 return (NULL);
255 n->m_next = m->m_next; /* splice new mbuf */
256 m->m_next = n;
257 newipsecstat.ips_mbinserted++;
258 if (hlen <= M_TRAILINGSPACE(m) + remain) {
259 /*
260 * New header fits in the old mbuf if we copy
261 * the remainder; just do the copy to the new
262 * mbuf and we're good to go.
263 */
264 memcpy(mtod(n, caddr_t),
265 mtod(m, caddr_t) + skip, remain);
266 n->m_len = remain;
267 m->m_len = skip + hlen;
268 *off = skip;
269 } else {
270 /*
271 * No space in the old mbuf for the new header.
272 * Make space in the new mbuf and check the
273 * remainder'd data fits too. If not then we
274 * must allocate an additional mbuf (yech).
275 */
276 n->m_len = 0;
277 if (remain + hlen > M_TRAILINGSPACE(n)) {
278 struct mbuf *n2;
279
280 MGET(n2, M_DONTWAIT, MT_DATA);
281 /* NB: new mbuf is on chain, let caller free */
282 if (n2 == NULL)
283 return (NULL);
284 n2->m_len = 0;
285 memcpy(mtod(n2, caddr_t),
286 mtod(m, caddr_t) + skip, remain);
287 n2->m_len = remain;
288 /* splice in second mbuf */
289 n2->m_next = n->m_next;
290 n->m_next = n2;
291 newipsecstat.ips_mbinserted++;
292 } else {
293 memcpy(mtod(n, caddr_t) + hlen,
294 mtod(m, caddr_t) + skip, remain);
295 n->m_len += remain;
296 }
297 m->m_len -= remain;
298 n->m_len += hlen;
299 m = n; /* header is at front ... */
300 *off = 0; /* ... of new mbuf */
301 }
302 } else {
303 /*
304 * Copy the remainder to the back of the mbuf
305 * so there's space to write the new header.
306 */
307 /* XXX can this be memcpy? does it handle overlap? */
308 ovbcopy(mtod(m, caddr_t) + skip,
309 mtod(m, caddr_t) + skip + hlen, remain);
310 m->m_len += hlen;
311 *off = skip;
312 }
313 m0->m_pkthdr.len += hlen; /* adjust packet length */
314 return m;
315 }
316
317 /*
318 * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
319 * length is updated, and a pointer to the first byte of the padding
320 * (which is guaranteed to be all in one mbuf) is returned.
321 */
322 caddr_t
323 m_pad(struct mbuf *m, int n)
324 {
325 register struct mbuf *m0, *m1;
326 register int len, pad;
327 caddr_t retval;
328
329 if (n <= 0) { /* No stupid arguments. */
330 DPRINTF(("m_pad: pad length invalid (%d)\n", n));
331 m_freem(m);
332 return NULL;
333 }
334
335 len = m->m_pkthdr.len;
336 pad = n;
337 m0 = m;
338
339 while (m0->m_len < len) {
340 IPSEC_ASSERT(m0->m_next != NULL, ("m_pad: m0 null, len %u m_len %u", len, m0->m_len));/*XXX*/
341 len -= m0->m_len;
342 m0 = m0->m_next;
343 }
344
345 if (m0->m_len != len) {
346 DPRINTF(("m_pad: length mismatch (should be %d instead of %d)\n",
347 m->m_pkthdr.len, m->m_pkthdr.len + m0->m_len - len));
348
349 m_freem(m);
350 return NULL;
351 }
352
353 /* Check for zero-length trailing mbufs, and find the last one. */
354 for (m1 = m0; m1->m_next; m1 = m1->m_next) {
355 if (m1->m_next->m_len != 0) {
356 DPRINTF(("m_pad: length mismatch (should be %d "
357 "instead of %d)\n",
358 m->m_pkthdr.len,
359 m->m_pkthdr.len + m1->m_next->m_len));
360
361 m_freem(m);
362 return NULL;
363 }
364
365 m0 = m1->m_next;
366 }
367
368 if (pad > M_TRAILINGSPACE(m0)) {
369 /* Add an mbuf to the chain. */
370 MGET(m1, M_DONTWAIT, MT_DATA);
371 if (m1 == 0) {
372 m_freem(m0);
373 DPRINTF(("m_pad: unable to get extra mbuf\n"));
374 return NULL;
375 }
376
377 m0->m_next = m1;
378 m0 = m1;
379 m0->m_len = 0;
380 }
381
382 retval = m0->m_data + m0->m_len;
383 m0->m_len += pad;
384 m->m_pkthdr.len += pad;
385
386 return retval;
387 }
388
389 /*
390 * Remove hlen data at offset skip in the packet. This is used by
391 * the protocols strip protocol headers and associated data (e.g. IV,
392 * authenticator) on input.
393 */
394 int
395 m_striphdr(struct mbuf *m, int skip, int hlen)
396 {
397 struct mbuf *m1;
398 int roff;
399
400 /* Find beginning of header */
401 m1 = m_getptr(m, skip, &roff);
402 if (m1 == NULL)
403 return (EINVAL);
404
405 /* Remove the header and associated data from the mbuf. */
406 if (roff == 0) {
407 /* The header was at the beginning of the mbuf */
408 newipsecstat.ips_input_front++;
409 m_adj(m1, hlen);
410 if ((m1->m_flags & M_PKTHDR) == 0)
411 m->m_pkthdr.len -= hlen;
412 } else if (roff + hlen >= m1->m_len) {
413 struct mbuf *mo;
414
415 /*
416 * Part or all of the header is at the end of this mbuf,
417 * so first let's remove the remainder of the header from
418 * the beginning of the remainder of the mbuf chain, if any.
419 */
420 newipsecstat.ips_input_end++;
421 if (roff + hlen > m1->m_len) {
422 /* Adjust the next mbuf by the remainder */
423 m_adj(m1->m_next, roff + hlen - m1->m_len);
424
425 /* The second mbuf is guaranteed not to have a pkthdr... */
426 m->m_pkthdr.len -= (roff + hlen - m1->m_len);
427 }
428
429 /* Now, let's unlink the mbuf chain for a second...*/
430 mo = m1->m_next;
431 m1->m_next = NULL;
432
433 /* ...and trim the end of the first part of the chain...sick */
434 m_adj(m1, -(m1->m_len - roff));
435 if ((m1->m_flags & M_PKTHDR) == 0)
436 m->m_pkthdr.len -= (m1->m_len - roff);
437
438 /* Finally, let's relink */
439 m1->m_next = mo;
440 } else {
441 /*
442 * The header lies in the "middle" of the mbuf; copy
443 * the remainder of the mbuf down over the header.
444 */
445 newipsecstat.ips_input_middle++;
446 ovbcopy(mtod(m1, u_char *) + roff + hlen,
447 mtod(m1, u_char *) + roff,
448 m1->m_len - (roff + hlen));
449 m1->m_len -= hlen;
450 m->m_pkthdr.len -= hlen;
451 }
452 return (0);
453 }
454
455 /*
456 * Diagnostic routine to check mbuf alignment as required by the
457 * crypto device drivers (that use DMA).
458 */
459 void
460 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
461 {
462 int roff;
463 struct mbuf *m = m_getptr(m0, off, &roff);
464 caddr_t addr;
465
466 if (m == NULL)
467 return;
468 printf("%s (off %u len %u): ", where, off, len);
469 addr = mtod(m, caddr_t) + roff;
470 do {
471 int mlen;
472
473 if (((uintptr_t) addr) & 3) {
474 printf("addr misaligned %p,", addr);
475 break;
476 }
477 mlen = m->m_len;
478 if (mlen > len)
479 mlen = len;
480 len -= mlen;
481 if (len && (mlen & 3)) {
482 printf("len mismatch %u,", mlen);
483 break;
484 }
485 m = m->m_next;
486 addr = m ? mtod(m, caddr_t) : NULL;
487 } while (m && len > 0);
488 for (m = m0; m; m = m->m_next)
489 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
490 printf("\n");
491 }
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