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
|
import os, struct, mmap
class NotELFFileError(Exception):
pass
class ELFFile:
EI_NIDENT = 16
EI_CLASS = 4
EI_DATA = 5
EI_VERSION = 6
EI_OSABI = 7
EI_ABIVERSION = 8
E_MACHINE = 0x12
# possible values for EI_CLASS
ELFCLASSNONE = 0
ELFCLASS32 = 1
ELFCLASS64 = 2
# possible value for EI_VERSION
EV_CURRENT = 1
# possible values for EI_DATA
EI_DATA_NONE = 0
EI_DATA_LSB = 1
EI_DATA_MSB = 2
PT_INTERP = 3
def my_assert(self, expectation, result):
if not expectation == result:
#print "'%x','%x' %s" % (ord(expectation), ord(result), self.name)
raise NotELFFileError("%s is not an ELF" % self.name)
def __init__(self, name):
self.name = name
self.objdump_output = {}
# Context Manager functions to close the mmap explicitly
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.data.close()
def open(self):
with open(self.name, "rb") as f:
try:
self.data = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
except ValueError:
# This means the file is empty
raise NotELFFileError("%s is empty" % self.name)
# Check the file has the minimum number of ELF table entries
if len(self.data) < ELFFile.EI_NIDENT + 4:
raise NotELFFileError("%s is not an ELF" % self.name)
# ELF header
self.my_assert(self.data[0], 0x7f)
self.my_assert(self.data[1], ord('E'))
self.my_assert(self.data[2], ord('L'))
self.my_assert(self.data[3], ord('F'))
if self.data[ELFFile.EI_CLASS] == ELFFile.ELFCLASS32:
self.bits = 32
elif self.data[ELFFile.EI_CLASS] == ELFFile.ELFCLASS64:
self.bits = 64
else:
# Not 32-bit or 64.. lets assert
raise NotELFFileError("ELF but not 32 or 64 bit.")
self.my_assert(self.data[ELFFile.EI_VERSION], ELFFile.EV_CURRENT)
self.endian = self.data[ELFFile.EI_DATA]
if self.endian not in (ELFFile.EI_DATA_LSB, ELFFile.EI_DATA_MSB):
raise NotELFFileError("Unexpected EI_DATA %x" % self.endian)
def osAbi(self):
return self.data[ELFFile.EI_OSABI]
def abiVersion(self):
return self.data[ELFFile.EI_ABIVERSION]
def abiSize(self):
return self.bits
def isLittleEndian(self):
return self.endian == ELFFile.EI_DATA_LSB
def isBigEndian(self):
return self.endian == ELFFile.EI_DATA_MSB
def getStructEndian(self):
return {ELFFile.EI_DATA_LSB: "<",
ELFFile.EI_DATA_MSB: ">"}[self.endian]
def getShort(self, offset):
return struct.unpack_from(self.getStructEndian() + "H", self.data, offset)[0]
def getWord(self, offset):
return struct.unpack_from(self.getStructEndian() + "i", self.data, offset)[0]
def isDynamic(self):
"""
Return True if there is a .interp segment (therefore dynamically
linked), otherwise False (statically linked).
"""
offset = self.getWord(self.bits == 32 and 0x1C or 0x20)
size = self.getShort(self.bits == 32 and 0x2A or 0x36)
count = self.getShort(self.bits == 32 and 0x2C or 0x38)
for i in range(0, count):
p_type = self.getWord(offset + i * size)
if p_type == ELFFile.PT_INTERP:
return True
return False
def machine(self):
"""
We know the endian stored in self.endian and we
know the position
"""
return self.getShort(ELFFile.E_MACHINE)
def run_objdump(self, cmd, d):
import bb.process
import sys
if cmd in self.objdump_output:
return self.objdump_output[cmd]
objdump = d.getVar('OBJDUMP', True)
env = os.environ.copy()
env["LC_ALL"] = "C"
env["PATH"] = d.getVar('PATH', True)
try:
bb.note("%s %s %s" % (objdump, cmd, self.name))
self.objdump_output[cmd] = bb.process.run([objdump, cmd, self.name], env=env, shell=False)[0]
return self.objdump_output[cmd]
except Exception as e:
bb.note("%s %s %s failed: %s" % (objdump, cmd, self.name, e))
return ""
def elf_machine_to_string(machine):
"""
Return the name of a given ELF e_machine field or the hex value as a string
if it isn't recognised.
"""
try:
return {
0x02: "SPARC",
0x03: "x86",
0x08: "MIPS",
0x14: "PowerPC",
0x28: "ARM",
0x2A: "SuperH",
0x32: "IA-64",
0x3E: "x86-64",
0xB7: "AArch64"
}[machine]
except:
return "Unknown (%s)" % repr(machine)
if __name__ == "__main__":
import sys
with ELFFile(sys.argv[1]) as elf:
elf.open()
print(elf.isDynamic())
|
