1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD$
29 */
30
31 /*
32 * IPsec-specific mbuf routines.
33 */
34
35 #include "opt_ipsec.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/malloc.h>
40 #include <sys/mbuf.h>
41 #include <sys/socket.h>
42
43 #include <net/vnet.h>
44 #include <netinet/in.h>
45 #include <netipsec/ipsec.h>
46
47 /*
48 * Make space for a new header of length hlen at skip bytes
49 * into the packet. When doing this we allocate new mbufs only
50 * when absolutely necessary. The mbuf where the new header
51 * is to go is returned together with an offset into the mbuf.
52 * If NULL is returned then the mbuf chain may have been modified;
53 * the caller is assumed to always free the chain.
54 */
55 struct mbuf *
m_makespace(struct mbuf * m0,int skip,int hlen,int * off)56 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
57 {
58 struct mbuf *m;
59 unsigned remain;
60
61 IPSEC_ASSERT(m0 != NULL, ("null mbuf"));
62 IPSEC_ASSERT(hlen < MHLEN, ("hlen too big: %u", hlen));
63
64 for (m = m0; m && skip > m->m_len; m = m->m_next)
65 skip -= m->m_len;
66 if (m == NULL)
67 return (NULL);
68 /*
69 * At this point skip is the offset into the mbuf m
70 * where the new header should be placed. Figure out
71 * if there's space to insert the new header. If so,
72 * and copying the remainder makes sense then do so.
73 * Otherwise insert a new mbuf in the chain, splitting
74 * the contents of m as needed.
75 */
76 remain = m->m_len - skip; /* data to move */
77 if (remain > skip &&
78 hlen + max_linkhdr < M_LEADINGSPACE(m)) {
79 /*
80 * mbuf has enough free space at the beginning.
81 * XXX: which operation is the most heavy - copying of
82 * possible several hundred of bytes or allocation
83 * of new mbuf? We can remove max_linkhdr check
84 * here, but it is possible that this will lead
85 * to allocation of new mbuf in Layer 2 code.
86 */
87 m->m_data -= hlen;
88 bcopy(mtodo(m, hlen), mtod(m, caddr_t), skip);
89 m->m_len += hlen;
90 *off = skip;
91 } else if (hlen > M_TRAILINGSPACE(m)) {
92 struct mbuf *n0, *n, **np;
93 int todo, len, done, alloc;
94
95 n0 = NULL;
96 np = &n0;
97 alloc = 0;
98 done = 0;
99 todo = remain;
100 while (todo > 0) {
101 if (todo > MHLEN) {
102 n = m_getcl(M_NOWAIT, m->m_type, 0);
103 len = MCLBYTES;
104 }
105 else {
106 n = m_get(M_NOWAIT, m->m_type);
107 len = MHLEN;
108 }
109 if (n == NULL) {
110 m_freem(n0);
111 return NULL;
112 }
113 *np = n;
114 np = &n->m_next;
115 alloc++;
116 len = min(todo, len);
117 memcpy(n->m_data, mtod(m, char *) + skip + done, len);
118 n->m_len = len;
119 done += len;
120 todo -= len;
121 }
122
123 if (hlen <= M_TRAILINGSPACE(m) + remain) {
124 m->m_len = skip + hlen;
125 *off = skip;
126 if (n0 != NULL) {
127 *np = m->m_next;
128 m->m_next = n0;
129 }
130 }
131 else {
132 n = m_get(M_NOWAIT, m->m_type);
133 if (n == NULL) {
134 m_freem(n0);
135 return NULL;
136 }
137 alloc++;
138
139 if ((n->m_next = n0) == NULL)
140 np = &n->m_next;
141 n0 = n;
142
143 *np = m->m_next;
144 m->m_next = n0;
145
146 n->m_len = hlen;
147 m->m_len = skip;
148
149 m = n; /* header is at front ... */
150 *off = 0; /* ... of new mbuf */
151 }
152 IPSECSTAT_INC(ips_mbinserted);
153 } else {
154 /*
155 * Copy the remainder to the back of the mbuf
156 * so there's space to write the new header.
157 */
158 bcopy(mtod(m, caddr_t) + skip,
159 mtod(m, caddr_t) + skip + hlen, remain);
160 m->m_len += hlen;
161 *off = skip;
162 }
163 m0->m_pkthdr.len += hlen; /* adjust packet length */
164 return m;
165 }
166
167 /*
168 * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
169 * length is updated, and a pointer to the first byte of the padding
170 * (which is guaranteed to be all in one mbuf) is returned.
171 */
172 caddr_t
m_pad(struct mbuf * m,int n)173 m_pad(struct mbuf *m, int n)
174 {
175 struct mbuf *m0, *m1;
176 int len, pad;
177 caddr_t retval;
178
179 if (n <= 0) { /* No stupid arguments. */
180 DPRINTF(("%s: pad length invalid (%d)\n", __func__, n));
181 m_freem(m);
182 return NULL;
183 }
184
185 len = m->m_pkthdr.len;
186 pad = n;
187 m0 = m;
188
189 while (m0->m_len < len) {
190 len -= m0->m_len;
191 m0 = m0->m_next;
192 }
193
194 if (m0->m_len != len) {
195 DPRINTF(("%s: length mismatch (should be %d instead of %d)\n",
196 __func__, m->m_pkthdr.len,
197 m->m_pkthdr.len + m0->m_len - len));
198
199 m_freem(m);
200 return NULL;
201 }
202
203 /* Check for zero-length trailing mbufs, and find the last one. */
204 for (m1 = m0; m1->m_next; m1 = m1->m_next) {
205 if (m1->m_next->m_len != 0) {
206 DPRINTF(("%s: length mismatch (should be %d instead "
207 "of %d)\n", __func__,
208 m->m_pkthdr.len,
209 m->m_pkthdr.len + m1->m_next->m_len));
210
211 m_freem(m);
212 return NULL;
213 }
214
215 m0 = m1->m_next;
216 }
217
218 if (pad > M_TRAILINGSPACE(m0)) {
219 /* Add an mbuf to the chain. */
220 MGET(m1, M_NOWAIT, MT_DATA);
221 if (m1 == NULL) {
222 m_freem(m0);
223 DPRINTF(("%s: unable to get extra mbuf\n", __func__));
224 return NULL;
225 }
226
227 m0->m_next = m1;
228 m0 = m1;
229 m0->m_len = 0;
230 }
231
232 retval = m0->m_data + m0->m_len;
233 m0->m_len += pad;
234 m->m_pkthdr.len += pad;
235
236 return retval;
237 }
238
239 /*
240 * Remove hlen data at offset skip in the packet. This is used by
241 * the protocols strip protocol headers and associated data (e.g. IV,
242 * authenticator) on input.
243 */
244 int
m_striphdr(struct mbuf * m,int skip,int hlen)245 m_striphdr(struct mbuf *m, int skip, int hlen)
246 {
247 struct mbuf *m1;
248 int roff;
249
250 /* Find beginning of header */
251 m1 = m_getptr(m, skip, &roff);
252 if (m1 == NULL)
253 return (EINVAL);
254
255 /* Remove the header and associated data from the mbuf. */
256 if (roff == 0) {
257 /* The header was at the beginning of the mbuf */
258 IPSECSTAT_INC(ips_input_front);
259 m_adj(m1, hlen);
260 if (m1 != m)
261 m->m_pkthdr.len -= hlen;
262 } else if (roff + hlen >= m1->m_len) {
263 struct mbuf *mo;
264 int adjlen;
265
266 /*
267 * Part or all of the header is at the end of this mbuf,
268 * so first let's remove the remainder of the header from
269 * the beginning of the remainder of the mbuf chain, if any.
270 */
271 IPSECSTAT_INC(ips_input_end);
272 if (roff + hlen > m1->m_len) {
273 adjlen = roff + hlen - m1->m_len;
274
275 /* Adjust the next mbuf by the remainder */
276 m_adj(m1->m_next, adjlen);
277
278 /* The second mbuf is guaranteed not to have a pkthdr... */
279 m->m_pkthdr.len -= adjlen;
280 }
281
282 /* Now, let's unlink the mbuf chain for a second...*/
283 mo = m1->m_next;
284 m1->m_next = NULL;
285
286 /* ...and trim the end of the first part of the chain...sick */
287 adjlen = m1->m_len - roff;
288 m_adj(m1, -adjlen);
289 if (m1 != m)
290 m->m_pkthdr.len -= adjlen;
291
292 /* Finally, let's relink */
293 m1->m_next = mo;
294 } else {
295 /*
296 * The header lies in the "middle" of the mbuf; copy
297 * the remainder of the mbuf down over the header.
298 */
299 IPSECSTAT_INC(ips_input_middle);
300 bcopy(mtod(m1, u_char *) + roff + hlen,
301 mtod(m1, u_char *) + roff,
302 m1->m_len - (roff + hlen));
303 m1->m_len -= hlen;
304 m->m_pkthdr.len -= hlen;
305 }
306 return (0);
307 }
308
309 /*
310 * Diagnostic routine to check mbuf alignment as required by the
311 * crypto device drivers (that use DMA).
312 */
313 void
m_checkalignment(const char * where,struct mbuf * m0,int off,int len)314 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
315 {
316 int roff;
317 struct mbuf *m = m_getptr(m0, off, &roff);
318 caddr_t addr;
319
320 if (m == NULL)
321 return;
322 printf("%s (off %u len %u): ", where, off, len);
323 addr = mtod(m, caddr_t) + roff;
324 do {
325 int mlen;
326
327 if (((uintptr_t) addr) & 3) {
328 printf("addr misaligned %p,", addr);
329 break;
330 }
331 mlen = m->m_len;
332 if (mlen > len)
333 mlen = len;
334 len -= mlen;
335 if (len && (mlen & 3)) {
336 printf("len mismatch %u,", mlen);
337 break;
338 }
339 m = m->m_next;
340 addr = m ? mtod(m, caddr_t) : NULL;
341 } while (m && len > 0);
342 for (m = m0; m; m = m->m_next)
343 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
344 printf("\n");
345 }
346