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
235
236
237
238
239
240
241
242
243
|
// Copyright (c) 2012, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// 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
// OWNER 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 "common/linux/elfutils.h"
#include <assert.h>
#include <string.h>
#include "common/linux/linux_libc_support.h"
#include "common/linux/elfutils-inl.h"
namespace google_breakpad {
namespace {
template<typename ElfClass>
void FindElfClassSection(const char* elf_base,
const char* section_name,
typename ElfClass::Word section_type,
const void** section_start,
size_t* section_size) {
typedef typename ElfClass::Ehdr Ehdr;
typedef typename ElfClass::Shdr Shdr;
assert(elf_base);
assert(section_start);
assert(section_size);
assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
if (elf_header->e_shoff == 0) {
*section_start = NULL;
*section_size = 0;
return;
}
const Shdr* sections =
GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff);
const Shdr* section_names = sections + elf_header->e_shstrndx;
const char* names =
GetOffset<ElfClass, char>(elf_header, section_names->sh_offset);
const char* names_end = names + section_names->sh_size;
const Shdr* section =
FindElfSectionByName<ElfClass>(section_name, section_type,
sections, names, names_end,
elf_header->e_shnum);
if (section != NULL && section->sh_size > 0) {
*section_start = elf_base + section->sh_offset;
*section_size = section->sh_size;
}
}
template<typename ElfClass>
void FindElfClassSegment(const char* elf_base,
typename ElfClass::Word segment_type,
wasteful_vector<ElfSegment>* segments) {
typedef typename ElfClass::Ehdr Ehdr;
typedef typename ElfClass::Phdr Phdr;
assert(elf_base);
assert(segments);
assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
const Phdr* phdrs =
GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff);
for (int i = 0; i < elf_header->e_phnum; ++i) {
if (phdrs[i].p_type == segment_type) {
ElfSegment seg = {};
seg.start = elf_base + phdrs[i].p_offset;
seg.size = phdrs[i].p_filesz;
segments->push_back(seg);
}
}
}
} // namespace
bool IsValidElf(const void* elf_base) {
return my_strncmp(reinterpret_cast<const char*>(elf_base),
ELFMAG, SELFMAG) == 0;
}
int ElfClass(const void* elf_base) {
const ElfW(Ehdr)* elf_header =
reinterpret_cast<const ElfW(Ehdr)*>(elf_base);
return elf_header->e_ident[EI_CLASS];
}
bool FindElfSection(const void* elf_mapped_base,
const char* section_name,
uint32_t section_type,
const void** section_start,
size_t* section_size) {
assert(elf_mapped_base);
assert(section_start);
assert(section_size);
*section_start = NULL;
*section_size = 0;
if (!IsValidElf(elf_mapped_base))
return false;
int cls = ElfClass(elf_mapped_base);
const char* elf_base =
static_cast<const char*>(elf_mapped_base);
if (cls == ELFCLASS32) {
FindElfClassSection<ElfClass32>(elf_base, section_name, section_type,
section_start, section_size);
return *section_start != NULL;
} else if (cls == ELFCLASS64) {
FindElfClassSection<ElfClass64>(elf_base, section_name, section_type,
section_start, section_size);
return *section_start != NULL;
}
return false;
}
bool FindElfSegments(const void* elf_mapped_base,
uint32_t segment_type,
wasteful_vector<ElfSegment>* segments) {
assert(elf_mapped_base);
assert(segments);
if (!IsValidElf(elf_mapped_base))
return false;
int cls = ElfClass(elf_mapped_base);
const char* elf_base =
static_cast<const char*>(elf_mapped_base);
if (cls == ELFCLASS32) {
FindElfClassSegment<ElfClass32>(elf_base, segment_type, segments);
return true;
} else if (cls == ELFCLASS64) {
FindElfClassSegment<ElfClass64>(elf_base, segment_type, segments);
return true;
}
return false;
}
template <typename ElfClass>
bool FindElfSoNameFromDynamicSection(const void* section_start,
size_t section_size,
const void* dynstr_start,
size_t dynstr_size,
char* soname,
size_t soname_size) {
typedef typename ElfClass::Dyn Dyn;
auto* dynamic = static_cast<const Dyn*>(section_start);
size_t dcount = section_size / sizeof(Dyn);
for (const Dyn* dyn = dynamic; dyn < dynamic + dcount; ++dyn) {
if (dyn->d_tag == DT_SONAME) {
const char* dynstr = static_cast<const char*>(dynstr_start);
if (dyn->d_un.d_val >= dynstr_size) {
// Beyond the end of the dynstr section
return false;
}
const char* str = dynstr + dyn->d_un.d_val;
const size_t maxsize = dynstr_size - dyn->d_un.d_val;
my_strlcpy(soname, str, maxsize < soname_size ? maxsize : soname_size);
return true;
}
}
return false;
}
bool ElfFileSoNameFromMappedFile(const void* elf_base,
char* soname,
size_t soname_size) {
if (!IsValidElf(elf_base)) {
// Not ELF
return false;
}
const void* segment_start;
size_t segment_size;
if (!FindElfSection(elf_base, ".dynamic", SHT_DYNAMIC, &segment_start,
&segment_size)) {
// No dynamic section
return false;
}
const void* dynstr_start;
size_t dynstr_size;
if (!FindElfSection(elf_base, ".dynstr", SHT_STRTAB, &dynstr_start,
&dynstr_size)) {
// No dynstr section
return false;
}
int cls = ElfClass(elf_base);
return cls == ELFCLASS32 ? FindElfSoNameFromDynamicSection<ElfClass32>(
segment_start, segment_size, dynstr_start,
dynstr_size, soname, soname_size)
: FindElfSoNameFromDynamicSection<ElfClass64>(
segment_start, segment_size, dynstr_start,
dynstr_size, soname, soname_size);
}
} // namespace google_breakpad
|
