1 /*
2 * Decoder of socket filter programs.
3 *
4 * Copyright (c) 2017 Dmitry V. Levin <ldv@altlinux.org>
5 * Copyright (c) 2017-2018 The strace developers.
6 * All rights reserved.
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 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include "defs.h"
32
33 #include "bpf_filter.h"
34
35 #include <linux/filter.h>
36 #include "xlat/skf_ad.h"
37 #include "xlat/skf_off.h"
38
39 static bool
print_sock_filter_k(const struct bpf_filter_block * const fp)40 print_sock_filter_k(const struct bpf_filter_block *const fp)
41 {
42 if (BPF_CLASS(fp->code) == BPF_LD && BPF_MODE(fp->code) == BPF_ABS) {
43 if (fp->k >= (unsigned int) SKF_AD_OFF) {
44 print_xlat32(SKF_AD_OFF);
45 tprints("+");
46 printxval(skf_ad, fp->k - (unsigned int) SKF_AD_OFF,
47 "SKF_AD_???");
48 return true;
49 } else if (fp->k >= (unsigned int) SKF_NET_OFF) {
50 print_xlat32(SKF_NET_OFF);
51 tprintf("+%u", fp->k - (unsigned int) SKF_NET_OFF);
52 return true;
53 } else if (fp->k >= (unsigned int) SKF_LL_OFF) {
54 print_xlat32(SKF_LL_OFF);
55 tprintf("+%u", fp->k - (unsigned int) SKF_LL_OFF);
56 return true;
57 }
58 }
59
60 return false;
61 }
62
63 void
print_sock_fprog(struct tcb * const tcp,const kernel_ulong_t addr,const unsigned short len)64 print_sock_fprog(struct tcb *const tcp, const kernel_ulong_t addr,
65 const unsigned short len)
66 {
67 print_bpf_fprog(tcp, addr, len, print_sock_filter_k);
68 }
69
70 void
decode_sock_fprog(struct tcb * const tcp,const kernel_ulong_t addr)71 decode_sock_fprog(struct tcb *const tcp, const kernel_ulong_t addr)
72 {
73 decode_bpf_fprog(tcp, addr, print_sock_filter_k);
74 }
75