1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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
29 /*
30 * IPsec-specific mbuf routines.
31 */
32
33 #include "opt_ipsec.h"
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/socket.h>
40
41 #include <net/vnet.h>
42 #include <netinet/in.h>
43 #include <netipsec/ipsec.h>
44
45 /*
46 * Make space for a new header of length hlen at skip bytes
47 * into the packet. When doing this we allocate new mbufs only
48 * when absolutely necessary. The mbuf where the new header
49 * is to go is returned together with an offset into the mbuf.
50 * If NULL is returned then the mbuf chain may have been modified;
51 * the caller is assumed to always free the chain.
52 */
53 struct mbuf *
m_makespace(struct mbuf * m0,int skip,int hlen,int * off)54 m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
55 {
56 struct mbuf *m;
57 unsigned remain;
58
59 IPSEC_ASSERT(m0 != NULL, ("null mbuf"));
60 IPSEC_ASSERT(hlen < MHLEN, ("hlen too big: %u", hlen));
61
62 for (m = m0; m && skip > m->m_len; m = m->m_next)
63 skip -= m->m_len;
64 if (m == NULL)
65 return (NULL);
66 /*
67 * At this point skip is the offset into the mbuf m
68 * where the new header should be placed. Figure out
69 * if there's space to insert the new header. If so,
70 * and copying the remainder makes sense then do so.
71 * Otherwise insert a new mbuf in the chain, splitting
72 * the contents of m as needed.
73 */
74 remain = m->m_len - skip; /* data to move */
75 if (remain > skip &&
76 hlen + max_linkhdr < M_LEADINGSPACE(m)) {
77 /*
78 * mbuf has enough free space at the beginning.
79 * XXX: which operation is the most heavy - copying of
80 * possible several hundred of bytes or allocation
81 * of new mbuf? We can remove max_linkhdr check
82 * here, but it is possible that this will lead
83 * to allocation of new mbuf in Layer 2 code.
84 */
85 m->m_data -= hlen;
86 bcopy(mtodo(m, hlen), mtod(m, caddr_t), skip);
87 m->m_len += hlen;
88 *off = skip;
89 } else if (hlen > M_TRAILINGSPACE(m)) {
90 struct mbuf *n0, *n, **np;
91 int todo, len, done;
92
93 n0 = NULL;
94 np = &n0;
95 done = 0;
96 todo = remain;
97 while (todo > 0) {
98 if (todo > MHLEN) {
99 n = m_getcl(M_NOWAIT, m->m_type, 0);
100 len = MCLBYTES;
101 }
102 else {
103 n = m_get(M_NOWAIT, m->m_type);
104 len = MHLEN;
105 }
106 if (n == NULL) {
107 m_freem(n0);
108 return NULL;
109 }
110 *np = n;
111 np = &n->m_next;
112 len = min(todo, len);
113 memcpy(n->m_data, mtod(m, char *) + skip + done, len);
114 n->m_len = len;
115 done += len;
116 todo -= len;
117 }
118
119 if (hlen <= M_TRAILINGSPACE(m) + remain) {
120 m->m_len = skip + hlen;
121 *off = skip;
122 if (n0 != NULL) {
123 *np = m->m_next;
124 m->m_next = n0;
125 }
126 }
127 else {
128 n = m_get(M_NOWAIT, m->m_type);
129 if (n == NULL) {
130 m_freem(n0);
131 return NULL;
132 }
133
134 if ((n->m_next = n0) == NULL)
135 np = &n->m_next;
136 n0 = n;
137
138 *np = m->m_next;
139 m->m_next = n0;
140
141 n->m_len = hlen;
142 m->m_len = skip;
143
144 m = n; /* header is at front ... */
145 *off = 0; /* ... of new mbuf */
146 }
147 IPSECSTAT_INC(ips_mbinserted);
148 } else {
149 /*
150 * Copy the remainder to the back of the mbuf
151 * so there's space to write the new header.
152 */
153 bcopy(mtod(m, caddr_t) + skip,
154 mtod(m, caddr_t) + skip + hlen, remain);
155 m->m_len += hlen;
156 *off = skip;
157 }
158 m0->m_pkthdr.len += hlen; /* adjust packet length */
159 return m;
160 }
161
162 /*
163 * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
164 * length is updated, and a pointer to the first byte of the padding
165 * (which is guaranteed to be all in one mbuf) is returned.
166 */
167 caddr_t
m_pad(struct mbuf * m,int n)168 m_pad(struct mbuf *m, int n)
169 {
170 struct mbuf *m0, *m1;
171 int len, pad;
172 caddr_t retval;
173
174 if (n <= 0) { /* No stupid arguments. */
175 DPRINTF(("%s: pad length invalid (%d)\n", __func__, n));
176 m_freem(m);
177 return NULL;
178 }
179
180 len = m->m_pkthdr.len;
181 pad = n;
182 m0 = m;
183
184 while (m0->m_len < len) {
185 len -= m0->m_len;
186 m0 = m0->m_next;
187 }
188
189 if (m0->m_len != len) {
190 DPRINTF(("%s: length mismatch (should be %d instead of %d)\n",
191 __func__, m->m_pkthdr.len,
192 m->m_pkthdr.len + m0->m_len - len));
193
194 m_freem(m);
195 return NULL;
196 }
197
198 /* Check for zero-length trailing mbufs, and find the last one. */
199 for (m1 = m0; m1->m_next; m1 = m1->m_next) {
200 if (m1->m_next->m_len != 0) {
201 DPRINTF(("%s: length mismatch (should be %d instead "
202 "of %d)\n", __func__,
203 m->m_pkthdr.len,
204 m->m_pkthdr.len + m1->m_next->m_len));
205
206 m_freem(m);
207 return NULL;
208 }
209
210 m0 = m1->m_next;
211 }
212
213 if (pad > M_TRAILINGSPACE(m0)) {
214 /* Add an mbuf to the chain. */
215 MGET(m1, M_NOWAIT, MT_DATA);
216 if (m1 == NULL) {
217 m_freem(m0);
218 DPRINTF(("%s: unable to get extra mbuf\n", __func__));
219 return NULL;
220 }
221
222 m0->m_next = m1;
223 m0 = m1;
224 m0->m_len = 0;
225 }
226
227 retval = m0->m_data + m0->m_len;
228 m0->m_len += pad;
229 m->m_pkthdr.len += pad;
230
231 return retval;
232 }
233
234 /*
235 * Remove hlen data at offset skip in the packet. This is used by
236 * the protocols strip protocol headers and associated data (e.g. IV,
237 * authenticator) on input.
238 */
239 int
m_striphdr(struct mbuf * m,int skip,int hlen)240 m_striphdr(struct mbuf *m, int skip, int hlen)
241 {
242 struct mbuf *m1;
243 int roff;
244
245 /* Find beginning of header */
246 m1 = m_getptr(m, skip, &roff);
247 if (m1 == NULL)
248 return (EINVAL);
249
250 /* Remove the header and associated data from the mbuf. */
251 if (roff == 0) {
252 /* The header was at the beginning of the mbuf */
253 IPSECSTAT_INC(ips_input_front);
254 m_adj(m1, hlen);
255 if (m1 != m)
256 m->m_pkthdr.len -= hlen;
257 } else if (roff + hlen >= m1->m_len) {
258 struct mbuf *mo;
259 int adjlen;
260
261 /*
262 * Part or all of the header is at the end of this mbuf,
263 * so first let's remove the remainder of the header from
264 * the beginning of the remainder of the mbuf chain, if any.
265 */
266 IPSECSTAT_INC(ips_input_end);
267 if (roff + hlen > m1->m_len) {
268 adjlen = roff + hlen - m1->m_len;
269
270 /* Adjust the next mbuf by the remainder */
271 m_adj(m1->m_next, adjlen);
272
273 /* The second mbuf is guaranteed not to have a pkthdr... */
274 m->m_pkthdr.len -= adjlen;
275 }
276
277 /* Now, let's unlink the mbuf chain for a second...*/
278 mo = m1->m_next;
279 m1->m_next = NULL;
280
281 /* ...and trim the end of the first part of the chain...sick */
282 adjlen = m1->m_len - roff;
283 m_adj(m1, -adjlen);
284 if (m1 != m)
285 m->m_pkthdr.len -= adjlen;
286
287 /* Finally, let's relink */
288 m1->m_next = mo;
289 } else {
290 /*
291 * The header lies in the "middle" of the mbuf; copy
292 * the remainder of the mbuf down over the header.
293 */
294 IPSECSTAT_INC(ips_input_middle);
295 bcopy(mtod(m1, u_char *) + roff + hlen,
296 mtod(m1, u_char *) + roff,
297 m1->m_len - (roff + hlen));
298 m1->m_len -= hlen;
299 m->m_pkthdr.len -= hlen;
300 }
301 return (0);
302 }
303
304 /*
305 * Diagnostic routine to check mbuf alignment as required by the
306 * crypto device drivers (that use DMA).
307 */
308 void
m_checkalignment(const char * where,struct mbuf * m0,int off,int len)309 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
310 {
311 int roff;
312 struct mbuf *m = m_getptr(m0, off, &roff);
313 caddr_t addr;
314
315 if (m == NULL)
316 return;
317 printf("%s (off %u len %u): ", where, off, len);
318 addr = mtod(m, caddr_t) + roff;
319 do {
320 int mlen;
321
322 if (((uintptr_t) addr) & 3) {
323 printf("addr misaligned %p,", addr);
324 break;
325 }
326 mlen = m->m_len;
327 if (mlen > len)
328 mlen = len;
329 len -= mlen;
330 if (len && (mlen & 3)) {
331 printf("len mismatch %u,", mlen);
332 break;
333 }
334 m = m->m_next;
335 addr = m ? mtod(m, caddr_t) : NULL;
336 } while (m && len > 0);
337 for (m = m0; m; m = m->m_next)
338 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
339 printf("\n");
340 }
341