1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
|
// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/390223051): Remove C-library calls to fix the errors.
#pragma allow_unsafe_libc_calls
#endif
#include "sandbox/linux/bpf_dsl/dump_bpf.h"
#include <inttypes.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string>
#include "base/strings/stringprintf.h"
#include "sandbox/linux/bpf_dsl/codegen.h"
#include "sandbox/linux/bpf_dsl/seccomp_macros.h"
#include "sandbox/linux/bpf_dsl/trap_registry.h"
#include "sandbox/linux/system_headers/linux_filter.h"
#include "sandbox/linux/system_headers/linux_seccomp.h"
namespace sandbox {
namespace bpf_dsl {
namespace {
const char* AluOpToken(uint32_t code) {
switch (BPF_OP(code)) {
case BPF_ADD:
return "+";
case BPF_SUB:
return "-";
case BPF_MUL:
return "*";
case BPF_DIV:
return "/";
case BPF_MOD:
return "%";
case BPF_OR:
return "|";
case BPF_XOR:
return "^";
case BPF_AND:
return "&";
case BPF_LSH:
return "<<";
case BPF_RSH:
return ">>";
default:
return "???";
}
}
const char* JmpOpToken(uint32_t code) {
switch (BPF_OP(code)) {
case BPF_JSET:
return "&";
case BPF_JEQ:
return "==";
case BPF_JGE:
return ">=";
default:
return "???";
}
}
const char* DataOffsetName(size_t off) {
switch (off) {
case SECCOMP_NR_IDX:
return "System call number";
case SECCOMP_ARCH_IDX:
return "Architecture";
case SECCOMP_IP_LSB_IDX:
return "Instruction pointer (LSB)";
case SECCOMP_IP_MSB_IDX:
return "Instruction pointer (MSB)";
default:
return "???";
}
}
void AppendInstruction(std::string* dst, size_t pc, const sock_filter& insn) {
base::StringAppendF(dst, "%3zu) ", pc);
switch (BPF_CLASS(insn.code)) {
case BPF_LD:
if (insn.code == BPF_LD + BPF_W + BPF_ABS) {
base::StringAppendF(dst, "LOAD %" PRIu32 " // ", insn.k);
size_t maybe_argno =
(insn.k - offsetof(struct arch_seccomp_data, args)) /
sizeof(uint64_t);
if (maybe_argno < 6 && insn.k == SECCOMP_ARG_LSB_IDX(maybe_argno)) {
base::StringAppendF(dst, "Argument %zu (LSB)\n", maybe_argno);
} else if (maybe_argno < 6 &&
insn.k == SECCOMP_ARG_MSB_IDX(maybe_argno)) {
base::StringAppendF(dst, "Argument %zu (MSB)\n", maybe_argno);
} else {
base::StringAppendF(dst, "%s\n", DataOffsetName(insn.k));
}
} else {
base::StringAppendF(dst, "Load ???\n");
}
break;
case BPF_JMP:
if (BPF_OP(insn.code) == BPF_JA) {
base::StringAppendF(dst, "JMP %zu\n", pc + insn.k + 1);
} else {
base::StringAppendF(
dst, "if A %s 0x%" PRIx32 "; then JMP %zu else JMP %zu\n",
JmpOpToken(insn.code), insn.k, pc + insn.jt + 1, pc + insn.jf + 1);
}
break;
case BPF_RET:
base::StringAppendF(dst, "RET 0x%" PRIx32 " // ", insn.k);
if ((insn.k & SECCOMP_RET_ACTION) == SECCOMP_RET_TRAP) {
base::StringAppendF(dst, "Trap #%" PRIu32 "\n",
insn.k & SECCOMP_RET_DATA);
} else if ((insn.k & SECCOMP_RET_ACTION) == SECCOMP_RET_ERRNO) {
base::StringAppendF(dst, "errno = %" PRIu32 "\n",
insn.k & SECCOMP_RET_DATA);
} else if ((insn.k & SECCOMP_RET_ACTION) == SECCOMP_RET_TRACE) {
base::StringAppendF(dst, "Trace #%" PRIu32 "\n",
insn.k & SECCOMP_RET_DATA);
} else if (insn.k == SECCOMP_RET_USER_NOTIF) {
base::StringAppendF(dst, "UserNotif\n");
} else if (insn.k == SECCOMP_RET_ALLOW) {
base::StringAppendF(dst, "Allowed\n");
} else if (insn.k == SECCOMP_RET_KILL) {
base::StringAppendF(dst, "Kill\n");
} else {
base::StringAppendF(dst, "???\n");
}
break;
case BPF_ALU:
if (BPF_OP(insn.code) == BPF_NEG) {
base::StringAppendF(dst, "A := -A\n");
} else {
base::StringAppendF(dst, "A := A %s 0x%" PRIx32 "\n",
AluOpToken(insn.code), insn.k);
}
break;
default:
base::StringAppendF(dst, "???\n");
break;
}
}
} // namespace
void DumpBPF::PrintProgram(const CodeGen::Program& program) {
fputs(StringPrintProgram(program).c_str(), stderr);
}
std::string DumpBPF::StringPrintProgram(const CodeGen::Program& program) {
std::string res;
for (size_t i = 0; i < program.size(); i++) {
AppendInstruction(&res, i + 1, program[i]);
}
return res;
}
} // namespace bpf_dsl
} // namespace sandbox
|
