1 /*
2 * Copyright (c) 2015 Dmitry V. Levin <ldv@altlinux.org>
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 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include "defs.h"
29
30 #ifdef HAVE_LINUX_SECCOMP_H
31 # include <linux/seccomp.h>
32 #endif
33 #include "xlat/seccomp_ops.h"
34 #include "xlat/seccomp_filter_flags.h"
35
36 #ifdef HAVE_LINUX_FILTER_H
37 # include <linux/filter.h>
38 # include "xlat/bpf_class.h"
39 # include "xlat/bpf_miscop.h"
40 # include "xlat/bpf_mode.h"
41 # include "xlat/bpf_op_alu.h"
42 # include "xlat/bpf_op_jmp.h"
43 # include "xlat/bpf_rval.h"
44 # include "xlat/bpf_size.h"
45 # include "xlat/bpf_src.h"
46
47 # ifndef SECCOMP_RET_ACTION
48 # define SECCOMP_RET_ACTION 0x7fff0000U
49 # endif
50 # include "xlat/seccomp_ret_action.h"
51 #endif
52
53 struct bpf_filter {
54 uint16_t code;
55 uint8_t jt;
56 uint8_t jf;
57 uint32_t k;
58 };
59
60 #ifdef HAVE_LINUX_FILTER_H
61
62 static void
decode_bpf_code(uint16_t code)63 decode_bpf_code(uint16_t code)
64 {
65 uint16_t i = code & ~BPF_CLASS(code);
66
67 printxval(bpf_class, BPF_CLASS(code), "BPF_???");
68 switch (BPF_CLASS(code)) {
69 case BPF_LD:
70 case BPF_LDX:
71 tprints("|");
72 printxval(bpf_size, BPF_SIZE(code), "BPF_???");
73 tprints("|");
74 printxval(bpf_mode, BPF_MODE(code), "BPF_???");
75 break;
76 case BPF_ST:
77 case BPF_STX:
78 if (i)
79 tprintf("|%#x /* %s */", i, "BPF_???");
80 break;
81 case BPF_ALU:
82 tprints("|");
83 printxval(bpf_src, BPF_SRC(code), "BPF_???");
84 tprints("|");
85 printxval(bpf_op_alu, BPF_OP(code), "BPF_???");
86 break;
87 case BPF_JMP:
88 tprints("|");
89 printxval(bpf_src, BPF_SRC(code), "BPF_???");
90 tprints("|");
91 printxval(bpf_op_jmp, BPF_OP(code), "BPF_???");
92 break;
93 case BPF_RET:
94 tprints("|");
95 printxval(bpf_rval, BPF_RVAL(code), "BPF_???");
96 i &= ~BPF_RVAL(code);
97 if (i)
98 tprintf("|%#x /* %s */", i, "BPF_???");
99 break;
100 case BPF_MISC:
101 tprints("|");
102 printxval(bpf_miscop, BPF_MISCOP(code), "BPF_???");
103 i &= ~BPF_MISCOP(code);
104 if (i)
105 tprintf("|%#x /* %s */", i, "BPF_???");
106 break;
107 }
108
109 }
110
111 #endif /* HAVE_LINUX_FILTER_H */
112
113 static void
decode_bpf_stmt(const struct bpf_filter * filter)114 decode_bpf_stmt(const struct bpf_filter *filter)
115 {
116 #ifdef HAVE_LINUX_FILTER_H
117 tprints("BPF_STMT(");
118 decode_bpf_code(filter->code);
119 tprints(", ");
120 if (BPF_CLASS(filter->code) == BPF_RET) {
121 unsigned int action = SECCOMP_RET_ACTION & filter->k;
122 unsigned int data = filter->k & ~action;
123
124 printxval(seccomp_ret_action, action, "SECCOMP_RET_???");
125 if (data)
126 tprintf("|%#x)", data);
127 else
128 tprints(")");
129 } else {
130 tprintf("%#x)", filter->k);
131 }
132 #else
133 tprintf("BPF_STMT(%#x, %#x)", filter->code, filter->k);
134 #endif /* HAVE_LINUX_FILTER_H */
135 }
136
137 static void
decode_bpf_jump(const struct bpf_filter * filter)138 decode_bpf_jump(const struct bpf_filter *filter)
139 {
140 #ifdef HAVE_LINUX_FILTER_H
141 tprints("BPF_JUMP(");
142 decode_bpf_code(filter->code);
143 tprintf(", %#x, %#x, %#x)",
144 filter->k, filter->jt, filter->jf);
145 #else
146 tprintf("BPF_JUMP(%#x, %#x, %#x, %#x)",
147 filter->code, filter->k, filter->jt, filter->jf);
148 #endif /* HAVE_LINUX_FILTER_H */
149 }
150
151 #ifndef BPF_MAXINSNS
152 # define BPF_MAXINSNS 4096
153 #endif
154
155 static bool
print_bpf_filter(struct tcb * tcp,void * elem_buf,size_t elem_size,void * data)156 print_bpf_filter(struct tcb *tcp, void *elem_buf, size_t elem_size, void *data)
157 {
158 const struct bpf_filter *filter = elem_buf;
159 unsigned int *pn = data;
160
161 if ((*pn)++ >= BPF_MAXINSNS) {
162 tprints("...");
163 return false;
164 }
165
166 if (filter->jt || filter->jf)
167 decode_bpf_jump(filter);
168 else
169 decode_bpf_stmt(filter);
170
171 return true;
172 }
173
174 void
print_seccomp_fprog(struct tcb * const tcp,const kernel_ulong_t addr,const unsigned short len)175 print_seccomp_fprog(struct tcb *const tcp, const kernel_ulong_t addr,
176 const unsigned short len)
177 {
178 if (abbrev(tcp)) {
179 printaddr(addr);
180 } else {
181 unsigned int insns = 0;
182 struct bpf_filter filter;
183
184 print_array(tcp, addr, len, &filter, sizeof(filter),
185 umoven_or_printaddr, print_bpf_filter, &insns);
186 }
187 }
188
189 #include "seccomp_fprog.h"
190
191 void
print_seccomp_filter(struct tcb * const tcp,const kernel_ulong_t addr)192 print_seccomp_filter(struct tcb *const tcp, const kernel_ulong_t addr)
193 {
194 struct seccomp_fprog fprog;
195
196 if (fetch_seccomp_fprog(tcp, addr, &fprog)) {
197 tprintf("{len=%hu, filter=", fprog.len);
198 print_seccomp_fprog(tcp, fprog.filter, fprog.len);
199 tprints("}");
200 }
201 }
202
203 static void
decode_seccomp_set_mode_strict(const unsigned int flags,const kernel_ulong_t addr)204 decode_seccomp_set_mode_strict(const unsigned int flags,
205 const kernel_ulong_t addr)
206 {
207 tprintf("%u, ", flags);
208 printaddr(addr);
209 }
210
SYS_FUNC(seccomp)211 SYS_FUNC(seccomp)
212 {
213 unsigned int op = tcp->u_arg[0];
214
215 printxval(seccomp_ops, op, "SECCOMP_SET_MODE_???");
216 tprints(", ");
217
218 if (op == SECCOMP_SET_MODE_FILTER) {
219 printflags(seccomp_filter_flags, tcp->u_arg[1],
220 "SECCOMP_FILTER_FLAG_???");
221 tprints(", ");
222 print_seccomp_filter(tcp, tcp->u_arg[2]);
223 } else {
224 decode_seccomp_set_mode_strict(tcp->u_arg[1],
225 tcp->u_arg[2]);
226 }
227
228 return RVAL_DECODED;
229 }
230