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
167
168
169
170
171
172
173
174
175
176
177
178
|
/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "DebugSession.h"
#include <AK/Optional.h>
#include <stdlib.h>
DebugSession::DebugSession(int pid)
: m_debugee_pid(pid)
, m_executable(String::format("/proc/%d/exe", pid))
, m_elf(reinterpret_cast<u8*>(m_executable.data()), m_executable.size())
{
}
DebugSession::~DebugSession()
{
if (!m_is_debugee_dead) {
if (ptrace(PT_DETACH, m_debugee_pid, 0, 0) < 0) {
perror("PT_DETACH");
}
}
}
OwnPtr<DebugSession> DebugSession::exec_and_attach(const String& command)
{
int pid = fork();
if (!pid) {
if (ptrace(PT_TRACE_ME, 0, 0, 0) < 0) {
perror("PT_TRACE_ME");
exit(1);
}
auto parts = command.split(' ');
ASSERT(!parts.is_empty());
const char** args = (const char**)calloc(parts.size() + 1, sizeof(const char*));
for (size_t i = 0; i < parts.size(); i++) {
args[i] = parts[i].characters();
}
int rc = execvp(args[0], const_cast<char**>(args));
if (rc < 0) {
perror("execvp");
}
ASSERT_NOT_REACHED();
}
if (waitpid(pid, nullptr, WSTOPPED) != pid) {
perror("waitpid");
return nullptr;
}
if (ptrace(PT_ATTACH, pid, 0, 0) < 0) {
perror("PT_ATTACH");
return nullptr;
}
if (waitpid(pid, nullptr, WSTOPPED) != pid) {
perror("waitpid");
return nullptr;
}
if (ptrace(PT_CONTINUE, pid, 0, 0) < 0) {
perror("continue");
return nullptr;
}
// We want to continue until the exit from the 'execve' sycsall.
// This ensures that when we start debugging the process
// it executes the target image, and not the forked image of the tracing process.
// NOTE: we only need to do this when we are debugging a new process (i.e not attaching to a process that's already running!)
if (waitpid(pid, nullptr, WSTOPPED) != pid) {
perror("wait_pid");
return nullptr;
}
return make<DebugSession>(pid);
}
bool DebugSession::poke(u32* address, u32 data)
{
if (ptrace(PT_POKE, m_debugee_pid, (void*)address, data) < 0) {
perror("PT_POKE");
return false;
}
return true;
}
Optional<u32> DebugSession::peek(u32* address) const
{
Optional<u32> result;
int rc = ptrace(PT_PEEK, m_debugee_pid, (void*)address, 0);
if (errno == 0)
result = static_cast<u32>(rc);
return result;
}
bool DebugSession::insert_breakpoint(void* address)
{
// We insert a software breakpoint by
// patching the first byte of the instruction at 'address'
// with the breakpoint instruction (int3)
if (m_breakpoints.contains(address))
return false;
auto original_bytes = peek(reinterpret_cast<u32*>(address));
if (!original_bytes.has_value())
return false;
if (!poke(reinterpret_cast<u32*>(address), (original_bytes.value() & ~(uint32_t)0xff) | BREAKPOINT_INSTRUCTION))
return false;
m_breakpoints.set(address, { address, original_bytes.value() });
return true;
}
void DebugSession::remove_breakpoint(const BreakPoint& breakpoint)
{
ASSERT(m_breakpoints.contains(breakpoint.address));
poke(reinterpret_cast<u32*>(reinterpret_cast<char*>(breakpoint.address)), breakpoint.original_first_word);
m_breakpoints.remove(breakpoint.address);
}
PtraceRegisters DebugSession::get_registers() const
{
PtraceRegisters regs;
if (ptrace(PT_GETREGS, m_debugee_pid, ®s, 0) < 0) {
perror("PT_GETREGS");
ASSERT_NOT_REACHED();
}
return regs;
}
void DebugSession::set_registers(const PtraceRegisters& regs)
{
if (ptrace(PT_SETREGS, m_debugee_pid, reinterpret_cast<void*>(&const_cast<PtraceRegisters&>(regs)), 0) < 0) {
perror("PT_SETREGS");
ASSERT_NOT_REACHED();
}
}
Optional<DebugSession::BreakPoint> DebugSession::get_matching_breakpoint(const PtraceRegisters& regs) const
{
return m_breakpoints.get(reinterpret_cast<void*>(regs.eip - 1));
}
void DebugSession::continue_debugee()
{
if (ptrace(PT_CONTINUE, m_debugee_pid, 0, 0) < 0) {
perror("continue");
ASSERT_NOT_REACHED();
}
}
|
