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 */
53struct mbuf *
54m_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 */
167caddr_t
168m_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 */
239int
240m_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 */
308void
309m_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