xref: /freebsd/sys/net/bpf_buffer.c (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
1 /*-
2  * Copyright (c) 2007 Seccuris Inc.
3  * All rights reserved.
4  *
5  * This sofware was developed by Robert N. M. Watson under contract to
6  * Seccuris Inc.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * Copyright (c) 1990, 1991, 1993
30  *	The Regents of the University of California.  All rights reserved.
31  *
32  * This code is derived from the Stanford/CMU enet packet filter,
33  * (net/enet.c) distributed as part of 4.3BSD, and code contributed
34  * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
35  * Berkeley Laboratory.
36  *
37  * Redistribution and use in source and binary forms, with or without
38  * modification, are permitted provided that the following conditions
39  * are met:
40  * 1. Redistributions of source code must retain the above copyright
41  *    notice, this list of conditions and the following disclaimer.
42  * 2. Redistributions in binary form must reproduce the above copyright
43  *    notice, this list of conditions and the following disclaimer in the
44  *    documentation and/or other materials provided with the distribution.
45  * 4. Neither the name of the University nor the names of its contributors
46  *    may be used to endorse or promote products derived from this software
47  *    without specific prior written permission.
48  *
49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59  * SUCH DAMAGE.
60  *
61  *      @(#)bpf.c	8.4 (Berkeley) 1/9/95
62  */
63 
64 #include <sys/cdefs.h>
65 __FBSDID("$FreeBSD$");
66 
67 #include "opt_bpf.h"
68 
69 #include <sys/param.h>
70 #include <sys/malloc.h>
71 #include <sys/mbuf.h>
72 #include <sys/socket.h>
73 #include <sys/uio.h>
74 #include <sys/kernel.h>
75 #include <sys/sysctl.h>
76 
77 #include <net/if.h>
78 #include <net/bpf.h>
79 #include <net/bpf_buffer.h>
80 #include <net/bpf_jitter.h>
81 #include <net/bpfdesc.h>
82 
83 /*
84  * Implement historical kernel memory buffering model for BPF: two malloc(9)
85  * kernel buffers are hung off of the descriptor.  The size is fixed prior to
86  * attaching to an ifnet, ad cannot be changed after that.  read(2) simply
87  * copies the data to user space using uiomove(9).
88  */
89 
90 static int bpf_bufsize = 4096;
91 SYSCTL_INT(_net_bpf, OID_AUTO, bufsize, CTLFLAG_RW,
92     &bpf_bufsize, 0, "Maximum capture buffer size in bytes");
93 static int bpf_maxbufsize = BPF_MAXBUFSIZE;
94 SYSCTL_INT(_net_bpf, OID_AUTO, maxbufsize, CTLFLAG_RW,
95     &bpf_maxbufsize, 0, "Default capture buffer in bytes");
96 
97 void
98 bpf_buffer_alloc(struct bpf_d *d)
99 {
100 
101 	KASSERT(d->bd_fbuf == NULL, ("bpf_buffer_alloc: bd_fbuf != NULL"));
102 	KASSERT(d->bd_sbuf == NULL, ("bpf_buffer_alloc: bd_sbuf != NULL"));
103 	KASSERT(d->bd_hbuf == NULL, ("bpf_buffer_alloc: bd_hbuf != NULL"));
104 
105 	d->bd_fbuf = (caddr_t)malloc(d->bd_bufsize, M_BPF, M_WAITOK);
106 	d->bd_sbuf = (caddr_t)malloc(d->bd_bufsize, M_BPF, M_WAITOK);
107 	d->bd_hbuf = NULL;
108 	d->bd_slen = 0;
109 	d->bd_hlen = 0;
110 }
111 
112 /*
113  * Simple data copy to the current kernel buffer.
114  */
115 void
116 bpf_buffer_append_bytes(struct bpf_d *d, caddr_t buf, u_int offset,
117     void *src, u_int len)
118 {
119 	u_char *src_bytes;
120 
121 	src_bytes = (u_char *)src;
122 	bcopy(src_bytes, buf + offset, len);
123 }
124 
125 /*
126  * Scatter-gather data copy from an mbuf chain to the current kernel buffer.
127  */
128 void
129 bpf_buffer_append_mbuf(struct bpf_d *d, caddr_t buf, u_int offset, void *src,
130     u_int len)
131 {
132 	const struct mbuf *m;
133 	u_char *dst;
134 	u_int count;
135 
136 	m = (struct mbuf *)src;
137 	dst = (u_char *)buf + offset;
138 	while (len > 0) {
139 		if (m == NULL)
140 			panic("bpf_mcopy");
141 		count = min(m->m_len, len);
142 		bcopy(mtod(m, void *), dst, count);
143 		m = m->m_next;
144 		dst += count;
145 		len -= count;
146 	}
147 }
148 
149 /*
150  * Free BPF kernel buffers on device close.
151  */
152 void
153 bpf_buffer_free(struct bpf_d *d)
154 {
155 
156 	if (d->bd_sbuf != NULL)
157 		free(d->bd_sbuf, M_BPF);
158 	if (d->bd_hbuf != NULL)
159 		free(d->bd_hbuf, M_BPF);
160 	if (d->bd_fbuf != NULL)
161 		free(d->bd_fbuf, M_BPF);
162 
163 #ifdef INVARIANTS
164 	d->bd_sbuf = d->bd_hbuf = d->bd_fbuf = (caddr_t)~0;
165 #endif
166 }
167 
168 /*
169  * This is a historical initialization that occurs when the BPF descriptor is
170  * first opened.  It does not imply selection of a buffer mode, so we don't
171  * allocate buffers here.
172  */
173 void
174 bpf_buffer_init(struct bpf_d *d)
175 {
176 
177 	d->bd_bufsize = bpf_bufsize;
178 }
179 
180 /*
181  * Allocate or resize buffers.
182  */
183 int
184 bpf_buffer_ioctl_sblen(struct bpf_d *d, u_int *i)
185 {
186 	u_int size;
187 
188 	BPFD_LOCK(d);
189 	if (d->bd_bif != NULL) {
190 		BPFD_UNLOCK(d);
191 		return (EINVAL);
192 	}
193 	size = *i;
194 	if (size > bpf_maxbufsize)
195 		*i = size = bpf_maxbufsize;
196 	else if (size < BPF_MINBUFSIZE)
197 		*i = size = BPF_MINBUFSIZE;
198 	d->bd_bufsize = size;
199 	BPFD_UNLOCK(d);
200 	return (0);
201 }
202 
203 /*
204  * Copy buffer storage to user space in read().
205  */
206 int
207 bpf_buffer_uiomove(struct bpf_d *d, caddr_t buf, u_int len, struct uio *uio)
208 {
209 
210 	return (uiomove(buf, len, uio));
211 }
212