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
179
180
181
182
183
184
185
186
187
188
189
|
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, Alex Major
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/Debug.h>
#include <AK/Iterator.h>
#include <AK/Vector.h>
#include <LibCore/ArgsParser.h>
#include <LibMain/Main.h>
#include <errno_codes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <syscall.h>
#define SC_NARG 4
FlatPtr arg[SC_NARG];
char outbuf[BUFSIZ];
using Arguments = Vector<const char*>;
using ArgIter = Arguments::Iterator;
static FlatPtr parse_from(ArgIter&);
template<>
struct AK::Formatter<Syscall::Function> : Formatter<StringView> {
ErrorOr<void> format(FormatBuilder& builder, Syscall::Function function)
{
return Formatter<StringView>::format(builder, to_string(function));
}
};
ErrorOr<int> serenity_main(Main::Arguments arguments)
{
bool output_buffer = false;
bool list_syscalls = false;
Vector<const char*> syscall_arguments;
Core::ArgsParser args_parser;
args_parser.set_general_help(
"Enables you to do a direct syscall, even those that use a 'SC_*_params' buffer.\n"
"Arguments can be literal strings, numbers, the output buffer, or parameter buffers:\n"
" - Arguments that begin with a comma are stripped of the comma and treated as string arguments, for example ',0x0' or ',['.\n"
" - 'buf' is replaced by a pointer to the output buffer.\n"
" - Numbers can be written like 1234 or 0xDEADC0DE.\n"
" - Parameter buffer (e.g. SC_realpath_params) can be passed by wrapping them in '[' and ']'. Note that '[' and ']' must be separate arguments to syscall(1). Buffers can be used recursively.\n"
" - The first argument may also be any syscall function name. Run 'syscall -l' to see the list.\n"
" - Arguments that cannot be interpreted are treated as string arguments, for example 'Hello, friends!'.\n"
"\n"
"Full example: syscall -o realpath [ /usr/share/man/man2/getgid.md 1024 buf 1024 ]");
args_parser.add_option(list_syscalls, "List all existing syscalls, and exit", "list-syscalls", 'l');
args_parser.add_option(output_buffer, "Output the contents of the buffer (beware of stray zero bytes!)", "output-buffer", 'o');
args_parser.add_positional_argument(syscall_arguments, "Syscall arguments; see general help.", "syscall-arguments", Core::ArgsParser::Required::No);
args_parser.parse(arguments);
if (list_syscalls) {
outln("syscall list:");
for (int sc = 0; sc < Syscall::Function::__Count; ++sc) {
outln(" \033[33;1m{}\033[0m - {}", sc, static_cast<Syscall::Function>(sc));
}
exit(0);
}
if (syscall_arguments.is_empty()) {
args_parser.print_usage(stderr, arguments.argv[0]);
exit(1);
}
ArgIter iter = syscall_arguments.begin();
for (size_t i = 0; i < SC_NARG && !iter.is_end(); i++) {
arg[i] = parse_from(iter);
}
if (!iter.is_end()) {
warnln("Too many arguments (did you want to use '[ parameter buffers ]'?)");
return -1;
}
if (arg[0] > Syscall::Function::__Count) {
for (int sc = 0; sc < Syscall::Function::__Count; ++sc) {
if (Syscall::to_string((Syscall::Function)sc) == (char const*)arg[0]) {
arg[0] = sc;
break;
}
}
if (arg[0] > Syscall::Function::__Count) {
warnln("Invalid syscall entry {}", (char*)arg[0]);
return -1;
}
}
dbgln_if(SYSCALL_1_DEBUG, "Calling {} {:p} {:p} {:p}\n", arg[0], arg[1], arg[2], arg[3]);
int rc = syscall(arg[0], arg[1], arg[2], arg[3]);
if (output_buffer)
fwrite(outbuf, 1, sizeof(outbuf), stdout);
if (-rc >= 0 && -rc < EMAXERRNO) {
warnln("Syscall return: {} ({})", rc, strerror(-rc));
} else {
warnln("Syscall return: {} (?)", rc);
}
return 0;
}
static FlatPtr as_buf(Vector<FlatPtr> params_vec)
{
size_t params_size = sizeof(FlatPtr) * params_vec.size();
size_t buf_size = round_up_to_power_of_two(params_size + 1, PAGE_SIZE);
void* buf = mmap(nullptr, buf_size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, 0, 0);
if (buf == MAP_FAILED) {
fprintf(stderr, "Warning: Could not allocate buffer of size %zu (low memory?)\n", buf_size);
exit(1);
}
// It's probably good to ensure zero-initialization.
memset(buf, 0, buf_size);
memcpy(buf, params_vec.data(), params_size);
if constexpr (SYSCALL_1_DEBUG) {
StringBuilder builder;
builder.append("Prepared [");
for (size_t i = 0; i < params_vec.size(); ++i) {
builder.appendff(" {:p}", params_vec[i]);
}
builder.appendff(" ] at {:p}", (FlatPtr)buf);
dbgln("{}", builder.to_string());
}
// Leak the buffer here. We need to keep it until the special syscall happens,
// and we terminate immediately afterwards anyway.
return (FlatPtr)buf;
}
static FlatPtr parse_parameter_buffer(ArgIter& iter)
{
Vector<FlatPtr> params_vec;
while (!iter.is_end()) {
if (strcmp(*iter, "]") == 0) {
++iter;
return as_buf(params_vec);
}
params_vec.append(parse_from(iter));
}
fprintf(stderr, "Error: Unmatched '['?!\n");
exit(1);
VERIFY_NOT_REACHED();
}
static FlatPtr parse_from(ArgIter& iter)
{
const char* this_arg = *iter;
++iter;
// Is it a forced literal?
if (this_arg[0] == ',') {
this_arg += 1;
dbgln_if(SYSCALL_1_DEBUG, "Using (forced) string >>{}<< at {:p}", this_arg, (FlatPtr)this_arg);
return (FlatPtr)this_arg;
}
// Is it the output buffer?
if (strcmp(this_arg, "buf") == 0)
return (FlatPtr)outbuf;
// Is it a parameter buffer?
if (strcmp(this_arg, "[") == 0)
return parse_parameter_buffer(iter);
// Is it a number?
char* endptr = nullptr;
FlatPtr l = strtoul(this_arg, &endptr, 0);
if (*endptr == 0) {
return l;
}
// Then it must be a string:
if (strcmp(this_arg, "]") == 0)
fprintf(stderr, "Warning: Treating unmatched ']' as literal string\n");
dbgln_if(SYSCALL_1_DEBUG, "Using (detected) string >>{}<< at {:p}", this_arg, (FlatPtr)this_arg);
return (FlatPtr)this_arg;
}
|
