1 /*-
2 * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: releng/7.4/sys/netipsec/ipsec_mbuf.c 201233 2009-12-29 23:27:15Z bz $
27 */
28
29 /*
30 * IPsec-specific mbuf routines.
31 */
32
33 #include "opt_param.h"
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/mbuf.h>
38 #include <sys/socket.h>
39
40 #include <net/route.h>
41 #include <netinet/in.h>
42
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 *
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 (hlen > M_TRAILINGSPACE(m)) {
76 struct mbuf *n0, *n, **np;
77 int todo, len, done, alloc;
78
79 n0 = NULL;
80 np = &n0;
81 alloc = 0;
82 done = 0;
83 todo = remain;
84 while (todo > 0) {
85 if (todo > MHLEN) {
86 n = m_getcl(M_DONTWAIT, m->m_type, 0);
87 len = MCLBYTES;
88 }
89 else {
90 n = m_get(M_DONTWAIT, m->m_type);
91 len = MHLEN;
92 }
93 if (n == NULL) {
94 m_freem(n0);
95 return NULL;
96 }
97 *np = n;
98 np = &n->m_next;
99 alloc++;
100 len = min(todo, len);
101 memcpy(n->m_data, mtod(m, char *) + skip + done, len);
102 n->m_len = len;
103 done += len;
104 todo -= len;
105 }
106
107 if (hlen <= M_TRAILINGSPACE(m) + remain) {
108 m->m_len = skip + hlen;
109 *off = skip;
110 if (n0 != NULL) {
111 *np = m->m_next;
112 m->m_next = n0;
113 }
114 }
115 else {
116 n = m_get(M_DONTWAIT, m->m_type);
117 if (n == NULL) {
118 m_freem(n0);
119 return NULL;
120 }
121 alloc++;
122
123 if ((n->m_next = n0) == NULL)
124 np = &n->m_next;
125 n0 = n;
126
127 *np = m->m_next;
128 m->m_next = n0;
129
130 n->m_len = hlen;
131 m->m_len = skip;
132
133 m = n; /* header is at front ... */
134 *off = 0; /* ... of new mbuf */
135 }
136 ipsec4stat.ips_mbinserted++;
137 } else {
138 /*
139 * Copy the remainder to the back of the mbuf
140 * so there's space to write the new header.
141 */
142 bcopy(mtod(m, caddr_t) + skip,
143 mtod(m, caddr_t) + skip + hlen, remain);
144 m->m_len += hlen;
145 *off = skip;
146 }
147 m0->m_pkthdr.len += hlen; /* adjust packet length */
148 return m;
149 }
150
151 /*
152 * m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
153 * length is updated, and a pointer to the first byte of the padding
154 * (which is guaranteed to be all in one mbuf) is returned.
155 */
156 caddr_t
157 m_pad(struct mbuf *m, int n)
158 {
159 register struct mbuf *m0, *m1;
160 register int len, pad;
161 caddr_t retval;
162
163 if (n <= 0) { /* No stupid arguments. */
164 DPRINTF(("%s: pad length invalid (%d)\n", __func__, n));
165 m_freem(m);
166 return NULL;
167 }
168
169 len = m->m_pkthdr.len;
170 pad = n;
171 m0 = m;
172
173 while (m0->m_len < len) {
174 len -= m0->m_len;
175 m0 = m0->m_next;
176 }
177
178 if (m0->m_len != len) {
179 DPRINTF(("%s: length mismatch (should be %d instead of %d)\n",
180 __func__, m->m_pkthdr.len,
181 m->m_pkthdr.len + m0->m_len - len));
182
183 m_freem(m);
184 return NULL;
185 }
186
187 /* Check for zero-length trailing mbufs, and find the last one. */
188 for (m1 = m0; m1->m_next; m1 = m1->m_next) {
189 if (m1->m_next->m_len != 0) {
190 DPRINTF(("%s: length mismatch (should be %d instead "
191 "of %d)\n", __func__,
192 m->m_pkthdr.len,
193 m->m_pkthdr.len + m1->m_next->m_len));
194
195 m_freem(m);
196 return NULL;
197 }
198
199 m0 = m1->m_next;
200 }
201
202 if (pad > M_TRAILINGSPACE(m0)) {
203 /* Add an mbuf to the chain. */
204 MGET(m1, M_DONTWAIT, MT_DATA);
205 if (m1 == 0) {
206 m_freem(m0);
207 DPRINTF(("%s: unable to get extra mbuf\n", __func__));
208 return NULL;
209 }
210
211 m0->m_next = m1;
212 m0 = m1;
213 m0->m_len = 0;
214 }
215
216 retval = m0->m_data + m0->m_len;
217 m0->m_len += pad;
218 m->m_pkthdr.len += pad;
219
220 return retval;
221 }
222
223 /*
224 * Remove hlen data at offset skip in the packet. This is used by
225 * the protocols strip protocol headers and associated data (e.g. IV,
226 * authenticator) on input.
227 */
228 int
229 m_striphdr(struct mbuf *m, int skip, int hlen)
230 {
231 struct mbuf *m1;
232 int roff;
233
234 /* Find beginning of header */
235 m1 = m_getptr(m, skip, &roff);
236 if (m1 == NULL)
237 return (EINVAL);
238
239 /* Remove the header and associated data from the mbuf. */
240 if (roff == 0) {
241 /* The header was at the beginning of the mbuf */
242 ipsec4stat.ips_input_front++;
243 m_adj(m1, hlen);
244 if ((m1->m_flags & M_PKTHDR) == 0)
245 m->m_pkthdr.len -= hlen;
246 } else if (roff + hlen >= m1->m_len) {
247 struct mbuf *mo;
248
249 /*
250 * Part or all of the header is at the end of this mbuf,
251 * so first let's remove the remainder of the header from
252 * the beginning of the remainder of the mbuf chain, if any.
253 */
254 ipsec4stat.ips_input_end++;
255 if (roff + hlen > m1->m_len) {
256 /* Adjust the next mbuf by the remainder */
257 m_adj(m1->m_next, roff + hlen - m1->m_len);
258
259 /* The second mbuf is guaranteed not to have a pkthdr... */
260 m->m_pkthdr.len -= (roff + hlen - m1->m_len);
261 }
262
263 /* Now, let's unlink the mbuf chain for a second...*/
264 mo = m1->m_next;
265 m1->m_next = NULL;
266
267 /* ...and trim the end of the first part of the chain...sick */
268 m_adj(m1, -(m1->m_len - roff));
269 if ((m1->m_flags & M_PKTHDR) == 0)
270 m->m_pkthdr.len -= (m1->m_len - roff);
271
272 /* Finally, let's relink */
273 m1->m_next = mo;
274 } else {
275 /*
276 * The header lies in the "middle" of the mbuf; copy
277 * the remainder of the mbuf down over the header.
278 */
279 ipsec4stat.ips_input_middle++;
280 bcopy(mtod(m1, u_char *) + roff + hlen,
281 mtod(m1, u_char *) + roff,
282 m1->m_len - (roff + hlen));
283 m1->m_len -= hlen;
284 m->m_pkthdr.len -= hlen;
285 }
286 return (0);
287 }
288
289 /*
290 * Diagnostic routine to check mbuf alignment as required by the
291 * crypto device drivers (that use DMA).
292 */
293 void
294 m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
295 {
296 int roff;
297 struct mbuf *m = m_getptr(m0, off, &roff);
298 caddr_t addr;
299
300 if (m == NULL)
301 return;
302 printf("%s (off %u len %u): ", where, off, len);
303 addr = mtod(m, caddr_t) + roff;
304 do {
305 int mlen;
306
307 if (((uintptr_t) addr) & 3) {
308 printf("addr misaligned %p,", addr);
309 break;
310 }
311 mlen = m->m_len;
312 if (mlen > len)
313 mlen = len;
314 len -= mlen;
315 if (len && (mlen & 3)) {
316 printf("len mismatch %u,", mlen);
317 break;
318 }
319 m = m->m_next;
320 addr = m ? mtod(m, caddr_t) : NULL;
321 } while (m && len > 0);
322 for (m = m0; m; m = m->m_next)
323 printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
324 printf("\n");
325 }
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