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 */
55struct mbuf *
56m_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 */
172caddr_t
173m_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 */
244int
245m_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 */
313void
314m_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