Line data Source code
1 : // Copyright (c) 2012, Google Inc.
2 : // All rights reserved.
3 : //
4 : // Redistribution and use in source and binary forms, with or without
5 : // modification, are permitted provided that the following conditions are
6 : // met:
7 : //
8 : // * Redistributions of source code must retain the above copyright
9 : // notice, this list of conditions and the following disclaimer.
10 : // * Redistributions in binary form must reproduce the above
11 : // copyright notice, this list of conditions and the following disclaimer
12 : // in the documentation and/or other materials provided with the
13 : // distribution.
14 : // * Neither the name of Google Inc. nor the names of its
15 : // contributors may be used to endorse or promote products derived from
16 : // this software without specific prior written permission.
17 : //
18 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 :
30 : #include "common/linux/elfutils.h"
31 :
32 : #include <assert.h>
33 : #include <string.h>
34 :
35 : #include "common/linux/linux_libc_support.h"
36 : #include "common/linux/elfutils-inl.h"
37 :
38 : namespace google_breakpad {
39 :
40 : namespace {
41 :
42 : template<typename ElfClass>
43 0 : void FindElfClassSection(const char *elf_base,
44 : const char *section_name,
45 : typename ElfClass::Word section_type,
46 : const void **section_start,
47 : size_t *section_size) {
48 : typedef typename ElfClass::Ehdr Ehdr;
49 : typedef typename ElfClass::Shdr Shdr;
50 :
51 0 : assert(elf_base);
52 0 : assert(section_start);
53 0 : assert(section_size);
54 :
55 0 : assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
56 :
57 0 : const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
58 0 : assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
59 :
60 : const Shdr* sections =
61 0 : GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff);
62 0 : const Shdr* section_names = sections + elf_header->e_shstrndx;
63 : const char* names =
64 0 : GetOffset<ElfClass, char>(elf_header, section_names->sh_offset);
65 0 : const char *names_end = names + section_names->sh_size;
66 :
67 : const Shdr* section =
68 0 : FindElfSectionByName<ElfClass>(section_name, section_type,
69 : sections, names, names_end,
70 0 : elf_header->e_shnum);
71 :
72 0 : if (section != NULL && section->sh_size > 0) {
73 0 : *section_start = elf_base + section->sh_offset;
74 0 : *section_size = section->sh_size;
75 : }
76 0 : }
77 :
78 : template<typename ElfClass>
79 0 : void FindElfClassSegment(const char *elf_base,
80 : typename ElfClass::Word segment_type,
81 : const void **segment_start,
82 : size_t *segment_size) {
83 : typedef typename ElfClass::Ehdr Ehdr;
84 : typedef typename ElfClass::Phdr Phdr;
85 :
86 0 : assert(elf_base);
87 0 : assert(segment_start);
88 0 : assert(segment_size);
89 :
90 0 : assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
91 :
92 0 : const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
93 0 : assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
94 :
95 : const Phdr* phdrs =
96 0 : GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff);
97 :
98 0 : for (int i = 0; i < elf_header->e_phnum; ++i) {
99 0 : if (phdrs[i].p_type == segment_type) {
100 0 : *segment_start = elf_base + phdrs[i].p_offset;
101 0 : *segment_size = phdrs[i].p_filesz;
102 0 : return;
103 : }
104 : }
105 : }
106 :
107 : } // namespace
108 :
109 0 : bool IsValidElf(const void* elf_base) {
110 0 : return my_strncmp(reinterpret_cast<const char*>(elf_base),
111 0 : ELFMAG, SELFMAG) == 0;
112 : }
113 :
114 0 : int ElfClass(const void* elf_base) {
115 : const ElfW(Ehdr)* elf_header =
116 0 : reinterpret_cast<const ElfW(Ehdr)*>(elf_base);
117 :
118 0 : return elf_header->e_ident[EI_CLASS];
119 : }
120 :
121 0 : bool FindElfSection(const void *elf_mapped_base,
122 : const char *section_name,
123 : uint32_t section_type,
124 : const void **section_start,
125 : size_t *section_size,
126 : int *elfclass) {
127 0 : assert(elf_mapped_base);
128 0 : assert(section_start);
129 0 : assert(section_size);
130 :
131 0 : *section_start = NULL;
132 0 : *section_size = 0;
133 :
134 0 : if (!IsValidElf(elf_mapped_base))
135 0 : return false;
136 :
137 0 : int cls = ElfClass(elf_mapped_base);
138 0 : if (elfclass) {
139 0 : *elfclass = cls;
140 : }
141 :
142 : const char* elf_base =
143 0 : static_cast<const char*>(elf_mapped_base);
144 :
145 0 : if (cls == ELFCLASS32) {
146 : FindElfClassSection<ElfClass32>(elf_base, section_name, section_type,
147 0 : section_start, section_size);
148 0 : return *section_start != NULL;
149 0 : } else if (cls == ELFCLASS64) {
150 : FindElfClassSection<ElfClass64>(elf_base, section_name, section_type,
151 0 : section_start, section_size);
152 0 : return *section_start != NULL;
153 : }
154 :
155 0 : return false;
156 : }
157 :
158 0 : bool FindElfSegment(const void *elf_mapped_base,
159 : uint32_t segment_type,
160 : const void **segment_start,
161 : size_t *segment_size,
162 : int *elfclass) {
163 0 : assert(elf_mapped_base);
164 0 : assert(segment_start);
165 0 : assert(segment_size);
166 :
167 0 : *segment_start = NULL;
168 0 : *segment_size = 0;
169 :
170 0 : if (!IsValidElf(elf_mapped_base))
171 0 : return false;
172 :
173 0 : int cls = ElfClass(elf_mapped_base);
174 0 : if (elfclass) {
175 0 : *elfclass = cls;
176 : }
177 :
178 : const char* elf_base =
179 0 : static_cast<const char*>(elf_mapped_base);
180 :
181 0 : if (cls == ELFCLASS32) {
182 : FindElfClassSegment<ElfClass32>(elf_base, segment_type,
183 0 : segment_start, segment_size);
184 0 : return *segment_start != NULL;
185 0 : } else if (cls == ELFCLASS64) {
186 : FindElfClassSegment<ElfClass64>(elf_base, segment_type,
187 0 : segment_start, segment_size);
188 0 : return *segment_start != NULL;
189 : }
190 :
191 0 : return false;
192 : }
193 :
194 : } // namespace google_breakpad
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