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
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/* Copyright (C) 1999-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Andreas Jaeger <aj@suse.de>, 1999 and
Jakub Jelinek <jakub@redhat.com>, 1999.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* This code is a heavily simplified version of the readelf program
that's part of the current binutils development version. For architectures
which need to handle both 32bit and 64bit ELF libraries, this file is
included twice for each arch size. */
/* check_ptr checks that a pointer is in the mmaped file and doesn't
point outside it. */
#undef check_ptr
#define check_ptr(ptr) \
do \
{ \
if ((void *)(ptr) < file_contents \
|| (void *)(ptr) > (file_contents+file_length)) \
{ \
error (0, 0, _("file %s is truncated\n"), file_name); \
return 1; \
} \
} \
while (0);
/* Returns 0 if everything is ok, != 0 in case of error. */
int
process_elf_file (const char *file_name, const char *lib, int *flag,
unsigned int *osversion, char **soname, void *file_contents,
size_t file_length)
{
int i;
unsigned int j;
ElfW(Addr) loadaddr;
unsigned int dynamic_addr;
size_t dynamic_size;
char *program_interpreter;
ElfW(Ehdr) *elf_header;
ElfW(Phdr) *elf_pheader, *segment;
ElfW(Dyn) *dynamic_segment, *dyn_entry;
char *dynamic_strings;
elf_header = (ElfW(Ehdr) *) file_contents;
*osversion = 0;
if (elf_header->e_ident [EI_CLASS] != ElfW (CLASS))
{
if (opt_verbose)
{
if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
error (0, 0, _("%s is a 32 bit ELF file.\n"), file_name);
else if (elf_header->e_ident [EI_CLASS] == ELFCLASS64)
error (0, 0, _("%s is a 64 bit ELF file.\n"), file_name);
else
error (0, 0, _("Unknown ELFCLASS in file %s.\n"), file_name);
}
return 1;
}
if (elf_header->e_type != ET_DYN)
{
error (0, 0, _("%s is not a shared object file (Type: %d).\n"), file_name,
elf_header->e_type);
return 1;
}
/* Get information from elf program header. */
elf_pheader = (ElfW(Phdr) *) (elf_header->e_phoff + file_contents);
check_ptr (elf_pheader);
/* The library is an elf library, now search for soname and
libc5/libc6. */
*flag = FLAG_ELF;
loadaddr = -1;
dynamic_addr = 0;
dynamic_size = 0;
program_interpreter = NULL;
for (i = 0, segment = elf_pheader;
i < elf_header->e_phnum; i++, segment++)
{
check_ptr (segment);
switch (segment->p_type)
{
case PT_LOAD:
if (loadaddr == (ElfW(Addr)) -1)
loadaddr = segment->p_vaddr - segment->p_offset;
break;
case PT_DYNAMIC:
if (dynamic_addr)
error (0, 0, _("more than one dynamic segment\n"));
dynamic_addr = segment->p_offset;
dynamic_size = segment->p_filesz;
break;
case PT_INTERP:
program_interpreter = (char *) (file_contents + segment->p_offset);
check_ptr (program_interpreter);
/* Check if this is enough to classify the binary. */
for (j = 0; j < sizeof (interpreters) / sizeof (interpreters [0]);
++j)
if (strcmp (program_interpreter, interpreters[j].soname) == 0)
{
*flag = interpreters[j].flag;
break;
}
break;
case PT_NOTE:
if (!*osversion && segment->p_filesz >= 32 && segment->p_align >= 4)
{
ElfW(Word) *abi_note = (ElfW(Word) *) (file_contents
+ segment->p_offset);
ElfW(Addr) size = segment->p_filesz;
while (abi_note [0] != 4 || abi_note [1] != 16
|| abi_note [2] != 1
|| memcmp (abi_note + 3, "GNU", 4) != 0)
{
#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
ElfW(Addr) note_size = 3 * sizeof (ElfW(Word))
+ ROUND (abi_note[0])
+ ROUND (abi_note[1]);
if (size - 32 < note_size || note_size == 0)
{
size = 0;
break;
}
size -= note_size;
abi_note = (void *) abi_note + note_size;
}
if (size == 0)
break;
*osversion = (abi_note [4] << 24) |
((abi_note [5] & 0xff) << 16) |
((abi_note [6] & 0xff) << 8) |
(abi_note [7] & 0xff);
}
break;
default:
break;
}
}
if (loadaddr == (ElfW(Addr)) -1)
{
/* Very strange. */
loadaddr = 0;
}
/* Now we can read the dynamic sections. */
if (dynamic_size == 0)
return 1;
dynamic_segment = (ElfW(Dyn) *) (file_contents + dynamic_addr);
check_ptr (dynamic_segment);
/* Find the string table. */
dynamic_strings = NULL;
for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL;
++dyn_entry)
{
check_ptr (dyn_entry);
if (dyn_entry->d_tag == DT_STRTAB)
{
dynamic_strings = (char *) (file_contents + dyn_entry->d_un.d_val - loadaddr);
check_ptr (dynamic_strings);
break;
}
}
if (dynamic_strings == NULL)
return 1;
/* Now read the DT_NEEDED and DT_SONAME entries. */
for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL;
++dyn_entry)
{
if (dyn_entry->d_tag == DT_NEEDED || dyn_entry->d_tag == DT_SONAME)
{
char *name = dynamic_strings + dyn_entry->d_un.d_val;
check_ptr (name);
if (dyn_entry->d_tag == DT_NEEDED)
{
if (*flag == FLAG_ELF)
{
/* Check if this is enough to classify the binary. */
for (j = 0;
j < sizeof (known_libs) / sizeof (known_libs [0]);
++j)
if (strcmp (name, known_libs [j].soname) == 0)
{
*flag = known_libs [j].flag;
break;
}
}
}
else if (dyn_entry->d_tag == DT_SONAME)
*soname = xstrdup (name);
/* Do we have everything we need? */
if (*soname && *flag != FLAG_ELF)
return 0;
}
}
return 0;
}
|
