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 static void
decode_bpf_stmt(const struct bpf_filter * filter)112 decode_bpf_stmt(const struct bpf_filter *filter)
113 {
114 #ifdef HAVE_LINUX_FILTER_H
115 tprints("BPF_STMT(");
116 decode_bpf_code(filter->code);
117 tprints(", ");
118 if (BPF_CLASS(filter->code) == BPF_RET) {
119 unsigned int action = SECCOMP_RET_ACTION & filter->k;
120 unsigned int data = filter->k & ~action;
121
122 printxval(seccomp_ret_action, action, "SECCOMP_RET_???");
123 if (data)
124 tprintf(" | %#x)", data);
125 else
126 tprints(")");
127 } else {
128 tprintf("%#x)", filter->k);
129 }
130 #else
131 tprintf("BPF_STMT(%#x, %#x)", filter->code, filter->k);
132 #endif /* HAVE_LINUX_FILTER_H */
133 }
134
135 static void
decode_bpf_jump(const struct bpf_filter * filter)136 decode_bpf_jump(const struct bpf_filter *filter)
137 {
138 #ifdef HAVE_LINUX_FILTER_H
139 tprints("BPF_JUMP(");
140 decode_bpf_code(filter->code);
141 tprintf(", %#x, %#x, %#x)",
142 filter->k, filter->jt, filter->jf);
143 #else
144 tprintf("BPF_JUMP(%#x, %#x, %#x, %#x)",
145 filter->code, filter->k, filter->jt, filter->jf);
146 #endif /* HAVE_LINUX_FILTER_H */
147 }
148
149 static void
decode_filter(const struct bpf_filter * filter)150 decode_filter(const struct bpf_filter *filter)
151 {
152 if (filter->jt || filter->jf)
153 decode_bpf_jump(filter);
154 else
155 decode_bpf_stmt(filter);
156 }
157
158 #endif /* HAVE_LINUX_FILTER_H */
159
160 #ifndef BPF_MAXINSNS
161 # define BPF_MAXINSNS 4096
162 #endif
163
164 static void
decode_fprog(struct tcb * tcp,unsigned short len,unsigned long addr)165 decode_fprog(struct tcb *tcp, unsigned short len, unsigned long addr)
166 {
167 if (!len || abbrev(tcp)) {
168 tprintf("{len = %u, filter = %#lx}", len, addr);
169 } else {
170 unsigned int i = 0;
171
172 tprints("[");
173 while (i < len && i < BPF_MAXINSNS) {
174 struct bpf_filter filter;
175
176 if (umove(tcp, addr, &filter) < 0)
177 break;
178 if (i)
179 tprints(", ");
180 decode_filter(&filter);
181
182 addr += sizeof(filter);
183 ++i;
184 }
185 if (i < len)
186 tprints("...");
187 tprints("]");
188 }
189 }
190
191 void
print_seccomp_filter(struct tcb * tcp,unsigned long addr)192 print_seccomp_filter(struct tcb *tcp, unsigned long addr)
193 {
194 if (addr) {
195 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
196 if (current_wordsize == 4) {
197 struct {
198 unsigned short len;
199 uint32_t filter;
200 } fprog;
201 if (umove(tcp, addr, &fprog) < 0)
202 tprintf("%#lx", addr);
203 else
204 decode_fprog(tcp, fprog.len, fprog.filter);
205 } else {
206 #endif
207 struct {
208 unsigned short len;
209 unsigned long filter;
210 } fprog;
211 if (umove(tcp, addr, &fprog) < 0)
212 tprintf("%#lx", addr);
213 else
214 decode_fprog(tcp, fprog.len, fprog.filter);
215 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
216 }
217 #endif
218 } else {
219 tprints("NULL");
220 }
221 }
222
223 static void
decode_seccomp_set_mode_strict(unsigned int flags,unsigned long addr)224 decode_seccomp_set_mode_strict(unsigned int flags, unsigned long addr)
225 {
226 tprintf("%u, ", flags);
227 if (addr)
228 tprintf("%#lx", addr);
229 else
230 tprints("NULL");
231 }
232
SYS_FUNC(seccomp)233 SYS_FUNC(seccomp)
234 {
235 if (entering(tcp)) {
236 unsigned int op = tcp->u_arg[0];
237
238 printxval(seccomp_ops, op, "SECCOMP_SET_MODE_???");
239 tprints(", ");
240
241 if (op == SECCOMP_SET_MODE_FILTER) {
242 printflags(seccomp_filter_flags, tcp->u_arg[1],
243 "SECCOMP_FILTER_FLAG_???");
244 tprints(", ");
245 print_seccomp_filter(tcp, tcp->u_arg[2]);
246 } else {
247 decode_seccomp_set_mode_strict(tcp->u_arg[1],
248 tcp->u_arg[2]);
249 }
250 }
251 return 0;
252 }
253