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 | 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 | assert(elf_base); |
52 | assert(section_start); |
53 | assert(section_size); |
54 | |
55 | assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0); |
56 | |
57 | const Ehdr* = reinterpret_cast<const Ehdr*>(elf_base); |
58 | assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass); |
59 | |
60 | if (elf_header->e_shoff == 0) { |
61 | *section_start = NULL; |
62 | *section_size = 0; |
63 | return; |
64 | } |
65 | |
66 | const Shdr* sections = |
67 | GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff); |
68 | const Shdr* section_names = sections + elf_header->e_shstrndx; |
69 | const char* names = |
70 | GetOffset<ElfClass, char>(elf_header, section_names->sh_offset); |
71 | const char* names_end = names + section_names->sh_size; |
72 | |
73 | const Shdr* section = |
74 | FindElfSectionByName<ElfClass>(section_name, section_type, |
75 | sections, names, names_end, |
76 | elf_header->e_shnum); |
77 | |
78 | if (section != NULL && section->sh_size > 0) { |
79 | *section_start = elf_base + section->sh_offset; |
80 | *section_size = section->sh_size; |
81 | } |
82 | } |
83 | |
84 | template<typename ElfClass> |
85 | void FindElfClassSegment(const char* elf_base, |
86 | typename ElfClass::Word segment_type, |
87 | wasteful_vector<ElfSegment>* segments) { |
88 | typedef typename ElfClass::Ehdr Ehdr; |
89 | typedef typename ElfClass::Phdr Phdr; |
90 | |
91 | assert(elf_base); |
92 | assert(segments); |
93 | |
94 | assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0); |
95 | |
96 | const Ehdr* = reinterpret_cast<const Ehdr*>(elf_base); |
97 | assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass); |
98 | |
99 | const Phdr* phdrs = |
100 | GetOffset<ElfClass, Phdr>(elf_header, elf_header->e_phoff); |
101 | |
102 | for (int i = 0; i < elf_header->e_phnum; ++i) { |
103 | if (phdrs[i].p_type == segment_type) { |
104 | ElfSegment seg = {}; |
105 | seg.start = elf_base + phdrs[i].p_offset; |
106 | seg.size = phdrs[i].p_filesz; |
107 | segments->push_back(seg); |
108 | } |
109 | } |
110 | } |
111 | |
112 | } // namespace |
113 | |
114 | bool IsValidElf(const void* elf_base) { |
115 | return my_strncmp(reinterpret_cast<const char*>(elf_base), |
116 | ELFMAG, SELFMAG) == 0; |
117 | } |
118 | |
119 | int ElfClass(const void* elf_base) { |
120 | const ElfW(Ehdr)* = |
121 | reinterpret_cast<const ElfW(Ehdr)*>(elf_base); |
122 | |
123 | return elf_header->e_ident[EI_CLASS]; |
124 | } |
125 | |
126 | bool FindElfSection(const void* elf_mapped_base, |
127 | const char* section_name, |
128 | uint32_t section_type, |
129 | const void** section_start, |
130 | size_t* section_size) { |
131 | assert(elf_mapped_base); |
132 | assert(section_start); |
133 | assert(section_size); |
134 | |
135 | *section_start = NULL; |
136 | *section_size = 0; |
137 | |
138 | if (!IsValidElf(elf_mapped_base)) |
139 | return false; |
140 | |
141 | int cls = ElfClass(elf_mapped_base); |
142 | const char* elf_base = |
143 | static_cast<const char*>(elf_mapped_base); |
144 | |
145 | if (cls == ELFCLASS32) { |
146 | FindElfClassSection<ElfClass32>(elf_base, section_name, section_type, |
147 | section_start, section_size); |
148 | return *section_start != NULL; |
149 | } else if (cls == ELFCLASS64) { |
150 | FindElfClassSection<ElfClass64>(elf_base, section_name, section_type, |
151 | section_start, section_size); |
152 | return *section_start != NULL; |
153 | } |
154 | |
155 | return false; |
156 | } |
157 | |
158 | bool FindElfSegments(const void* elf_mapped_base, |
159 | uint32_t segment_type, |
160 | wasteful_vector<ElfSegment>* segments) { |
161 | assert(elf_mapped_base); |
162 | assert(segments); |
163 | |
164 | if (!IsValidElf(elf_mapped_base)) |
165 | return false; |
166 | |
167 | int cls = ElfClass(elf_mapped_base); |
168 | const char* elf_base = |
169 | static_cast<const char*>(elf_mapped_base); |
170 | |
171 | if (cls == ELFCLASS32) { |
172 | FindElfClassSegment<ElfClass32>(elf_base, segment_type, segments); |
173 | return true; |
174 | } else if (cls == ELFCLASS64) { |
175 | FindElfClassSegment<ElfClass64>(elf_base, segment_type, segments); |
176 | return true; |
177 | } |
178 | |
179 | return false; |
180 | } |
181 | |
182 | template <typename ElfClass> |
183 | bool FindElfSoNameFromDynamicSection(const void* section_start, |
184 | size_t section_size, |
185 | const void* dynstr_start, |
186 | size_t dynstr_size, |
187 | char* soname, |
188 | size_t soname_size) { |
189 | typedef typename ElfClass::Dyn Dyn; |
190 | |
191 | auto* dynamic = static_cast<const Dyn*>(section_start); |
192 | size_t dcount = section_size / sizeof(Dyn); |
193 | for (const Dyn* dyn = dynamic; dyn < dynamic + dcount; ++dyn) { |
194 | if (dyn->d_tag == DT_SONAME) { |
195 | const char* dynstr = static_cast<const char*>(dynstr_start); |
196 | if (dyn->d_un.d_val >= dynstr_size) { |
197 | // Beyond the end of the dynstr section |
198 | return false; |
199 | } |
200 | const char* str = dynstr + dyn->d_un.d_val; |
201 | const size_t maxsize = dynstr_size - dyn->d_un.d_val; |
202 | my_strlcpy(soname, str, maxsize < soname_size ? maxsize : soname_size); |
203 | return true; |
204 | } |
205 | } |
206 | |
207 | return false; |
208 | } |
209 | |
210 | bool ElfFileSoNameFromMappedFile(const void* elf_base, |
211 | char* soname, |
212 | size_t soname_size) { |
213 | if (!IsValidElf(elf_base)) { |
214 | // Not ELF |
215 | return false; |
216 | } |
217 | |
218 | const void* segment_start; |
219 | size_t segment_size; |
220 | if (!FindElfSection(elf_base, ".dynamic" , SHT_DYNAMIC, &segment_start, |
221 | &segment_size)) { |
222 | // No dynamic section |
223 | return false; |
224 | } |
225 | |
226 | const void* dynstr_start; |
227 | size_t dynstr_size; |
228 | if (!FindElfSection(elf_base, ".dynstr" , SHT_STRTAB, &dynstr_start, |
229 | &dynstr_size)) { |
230 | // No dynstr section |
231 | return false; |
232 | } |
233 | |
234 | int cls = ElfClass(elf_base); |
235 | return cls == ELFCLASS32 ? FindElfSoNameFromDynamicSection<ElfClass32>( |
236 | segment_start, segment_size, dynstr_start, |
237 | dynstr_size, soname, soname_size) |
238 | : FindElfSoNameFromDynamicSection<ElfClass64>( |
239 | segment_start, segment_size, dynstr_start, |
240 | dynstr_size, soname, soname_size); |
241 | } |
242 | |
243 | } // namespace google_breakpad |
244 | |