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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
#!/usr/bin/env python
#
# Copyright (C) 2018 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
A tool to extract kernel information from a kernel image.
"""
import argparse
import subprocess
import sys
import re
CONFIG_PREFIX = b'IKCFG_ST'
GZIP_HEADER = b'\037\213\010'
COMPRESSION_ALGO = (
(["gzip", "-d"], GZIP_HEADER),
(["xz", "-d"], b'\3757zXZ\000'),
(["bzip2", "-d"], b'BZh'),
(["lz4", "-d", "-l"], b'\002\041\114\030'),
# These are not supported in the build system yet.
# (["unlzma"], b'\135\0\0\0'),
# (["lzop", "-d"], b'\211\114\132'),
)
# "Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
# LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n";
LINUX_BANNER_PREFIX = b'Linux version '
LINUX_BANNER_REGEX = LINUX_BANNER_PREFIX + \
r'([0-9]+[.][0-9]+[.][0-9]+).* \(.*@.*\) \(.*\) .*\n'
def get_version(input_bytes, start_idx):
null_idx = input_bytes.find('\x00', start_idx)
if null_idx < 0:
return None
try:
linux_banner = input_bytes[start_idx:null_idx].decode()
except UnicodeDecodeError:
return None
mo = re.match(LINUX_BANNER_REGEX, linux_banner)
if mo:
return mo.group(1)
return None
def dump_version(input_bytes):
idx = 0
while True:
idx = input_bytes.find(LINUX_BANNER_PREFIX, idx)
if idx < 0:
return None
version = get_version(input_bytes, idx)
if version:
return version
idx += len(LINUX_BANNER_PREFIX)
def dump_configs(input_bytes):
"""
Dump kernel configuration from input_bytes. This can be done when
CONFIG_IKCONFIG is enabled, which is a requirement on Treble devices.
The kernel configuration is archived in GZip format right after the magic
string 'IKCFG_ST' in the built kernel.
"""
# Search for magic string + GZip header
idx = input_bytes.find(CONFIG_PREFIX + GZIP_HEADER)
if idx < 0:
return None
# Seek to the start of the archive
idx += len(CONFIG_PREFIX)
sp = subprocess.Popen(["gzip", "-d", "-c"], stdin=subprocess.PIPE,
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
o, _ = sp.communicate(input=input_bytes[idx:])
if sp.returncode == 1: # error
return None
# success or trailing garbage warning
assert sp.returncode in (0, 2), sp.returncode
return o
def try_decompress_bytes(cmd, input_bytes):
sp = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
o, _ = sp.communicate(input=input_bytes)
# ignore errors
return o
def try_decompress(cmd, search_bytes, input_bytes):
idx = 0
while True:
idx = input_bytes.find(search_bytes, idx)
if idx < 0:
raise StopIteration()
yield try_decompress_bytes(cmd, input_bytes[idx:])
idx += 1
def decompress_dump(func, input_bytes):
"""
Run func(input_bytes) first; and if that fails (returns value evaluates to
False), then try different decompression algorithm before running func.
"""
o = func(input_bytes)
if o:
return o
for cmd, search_bytes in COMPRESSION_ALGO:
for decompressed in try_decompress(cmd, search_bytes, input_bytes):
if decompressed:
o = decompress_dump(func, decompressed)
if o:
return o
# Force decompress the whole file even if header doesn't match
decompressed = try_decompress_bytes(cmd, input_bytes)
if decompressed:
o = decompress_dump(func, decompressed)
if o:
return o
def main():
parser = argparse.ArgumentParser(
formatter_class=argparse.RawTextHelpFormatter,
description=__doc__ +
"\nThese algorithms are tried when decompressing the image:\n " +
" ".join(tup[0][0] for tup in COMPRESSION_ALGO))
parser.add_argument('--input',
help='Input kernel image. If not specified, use stdin',
metavar='FILE',
type=argparse.FileType('rb'),
default=sys.stdin)
parser.add_argument('--output-configs',
help='If specified, write configs. Use stdout if no file '
'is specified.',
metavar='FILE',
nargs='?',
type=argparse.FileType('wb'),
const=sys.stdout)
parser.add_argument('--output-version',
help='If specified, write version. Use stdout if no file '
'is specified.',
metavar='FILE',
nargs='?',
type=argparse.FileType('wb'),
const=sys.stdout)
parser.add_argument('--tools',
help='Decompression tools to use. If not specified, PATH '
'is searched.',
metavar='ALGORITHM:EXECUTABLE',
nargs='*')
args = parser.parse_args()
tools = {pair[0]: pair[1]
for pair in (token.split(':') for token in args.tools or [])}
for cmd, _ in COMPRESSION_ALGO:
if cmd[0] in tools:
cmd[0] = tools[cmd[0]]
input_bytes = args.input.read()
ret = 0
if args.output_configs is not None:
o = decompress_dump(dump_configs, input_bytes)
if o:
args.output_configs.write(o)
else:
sys.stderr.write(
"Cannot extract kernel configs in {}".format(args.input.name))
ret = 1
if args.output_version is not None:
o = decompress_dump(dump_version, input_bytes)
if o:
args.output_version.write(o)
else:
sys.stderr.write(
"Cannot extract kernel versions in {}".format(args.input.name))
ret = 1
return ret
if __name__ == '__main__':
exit(main())
|
