1 : // Copyright (c) 2006, 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 : // file_id.cc: Return a unique identifier for a file
31 : //
32 : // See file_id.h for documentation
33 : //
34 :
35 : #include "common/linux/file_id.h"
36 :
37 : #include <arpa/inet.h>
38 : #include <assert.h>
39 : #include <elf.h>
40 : #include <fcntl.h>
41 : #if defined(__ANDROID__)
42 : #include "client/linux/android_link.h"
43 : #else
44 : #include <link.h>
45 : #endif
46 : #include <stdio.h>
47 : #include <string.h>
48 : #include <sys/mman.h>
49 : #include <sys/stat.h>
50 : #include <unistd.h>
51 :
52 : #include <algorithm>
53 :
54 : #include "common/linux/linux_libc_support.h"
55 : #include "common/linux/linux_syscall_support.h"
56 :
57 : namespace google_breakpad {
58 :
59 124 : FileID::FileID(const char* path) {
60 124 : strncpy(path_, path, sizeof(path_));
61 124 : }
62 :
63 : struct ElfClass32 {
64 : typedef Elf32_Ehdr Ehdr;
65 : typedef Elf32_Shdr Shdr;
66 : static const int kClass = ELFCLASS32;
67 : };
68 :
69 : struct ElfClass64 {
70 : typedef Elf64_Ehdr Ehdr;
71 : typedef Elf64_Shdr Shdr;
72 : static const int kClass = ELFCLASS64;
73 : };
74 :
75 : // These three functions are also used inside the crashed process, so be safe
76 : // and use the syscall/libc wrappers instead of direct syscalls or libc.
77 : template<typename ElfClass>
78 124 : static void FindElfClassTextSection(const char *elf_base,
79 : const void **text_start,
80 : int *text_size) {
81 : typedef typename ElfClass::Ehdr Ehdr;
82 : typedef typename ElfClass::Shdr Shdr;
83 :
84 124 : assert(elf_base);
85 124 : assert(text_start);
86 124 : assert(text_size);
87 :
88 124 : assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
89 :
90 124 : const char* text_section_name = ".text";
91 124 : int name_len = my_strlen(text_section_name);
92 :
93 124 : const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
94 124 : assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
95 :
96 : const Shdr* sections =
97 124 : reinterpret_cast<const Shdr*>(elf_base + elf_header->e_shoff);
98 124 : const Shdr* string_section = sections + elf_header->e_shstrndx;
99 :
100 124 : const Shdr* text_section = NULL;
101 1586 : for (int i = 0; i < elf_header->e_shnum; ++i) {
102 1586 : if (sections[i].sh_type == SHT_PROGBITS) {
103 : const char* section_name = (char*)(elf_base +
104 : string_section->sh_offset +
105 482 : sections[i].sh_name);
106 482 : if (!my_strncmp(section_name, text_section_name, name_len)) {
107 124 : text_section = §ions[i];
108 124 : break;
109 : }
110 : }
111 : }
112 124 : if (text_section != NULL && text_section->sh_size > 0) {
113 124 : *text_start = elf_base + text_section->sh_offset;
114 124 : *text_size = text_section->sh_size;
115 : }
116 124 : }
117 :
118 124 : static bool FindElfTextSection(const void *elf_mapped_base,
119 : const void **text_start,
120 : int *text_size) {
121 124 : assert(elf_mapped_base);
122 124 : assert(text_start);
123 124 : assert(text_size);
124 :
125 : const char* elf_base =
126 124 : static_cast<const char*>(elf_mapped_base);
127 : const ElfW(Ehdr)* elf_header =
128 124 : reinterpret_cast<const ElfW(Ehdr)*>(elf_base);
129 124 : if (my_strncmp(elf_base, ELFMAG, SELFMAG) != 0)
130 0 : return false;
131 :
132 124 : if (elf_header->e_ident[EI_CLASS] == ELFCLASS32) {
133 124 : FindElfClassTextSection<ElfClass32>(elf_base, text_start, text_size);
134 0 : } else if (elf_header->e_ident[EI_CLASS] == ELFCLASS64) {
135 0 : FindElfClassTextSection<ElfClass64>(elf_base, text_start, text_size);
136 : } else {
137 0 : return false;
138 : }
139 :
140 124 : return true;
141 : }
142 :
143 : // static
144 124 : bool FileID::ElfFileIdentifierFromMappedFile(void* base,
145 : uint8_t identifier[kMDGUIDSize])
146 : {
147 124 : const void* text_section = NULL;
148 124 : int text_size = 0;
149 124 : bool success = false;
150 124 : if (FindElfTextSection(base, &text_section, &text_size) && (text_size > 0)) {
151 124 : my_memset(identifier, 0, kMDGUIDSize);
152 124 : const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section);
153 124 : const uint8_t* ptr_end = ptr + std::min(text_size, 4096);
154 31831 : while (ptr < ptr_end) {
155 536911 : for (unsigned i = 0; i < kMDGUIDSize; i++)
156 505328 : identifier[i] ^= ptr[i];
157 31583 : ptr += kMDGUIDSize;
158 : }
159 124 : success = true;
160 : }
161 124 : return success;
162 : }
163 :
164 0 : bool FileID::ElfFileIdentifier(uint8_t identifier[kMDGUIDSize]) {
165 0 : int fd = open(path_, O_RDONLY);
166 0 : if (fd < 0)
167 0 : return false;
168 : struct stat st;
169 0 : if (fstat(fd, &st) != 0) {
170 0 : close(fd);
171 0 : return false;
172 : }
173 : void* base = mmap(NULL, st.st_size,
174 0 : PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
175 0 : close(fd);
176 0 : if (base == MAP_FAILED)
177 0 : return false;
178 :
179 0 : bool success = ElfFileIdentifierFromMappedFile(base, identifier);
180 0 : munmap(base, st.st_size);
181 0 : return success;
182 : }
183 :
184 : // static
185 124 : void FileID::ConvertIdentifierToString(const uint8_t identifier[kMDGUIDSize],
186 : char* buffer, int buffer_length) {
187 : uint8_t identifier_swapped[kMDGUIDSize];
188 :
189 : // Endian-ness swap to match dump processor expectation.
190 124 : memcpy(identifier_swapped, identifier, kMDGUIDSize);
191 124 : uint32_t* data1 = reinterpret_cast<uint32_t*>(identifier_swapped);
192 124 : *data1 = htonl(*data1);
193 124 : uint16_t* data2 = reinterpret_cast<uint16_t*>(identifier_swapped + 4);
194 124 : *data2 = htons(*data2);
195 124 : uint16_t* data3 = reinterpret_cast<uint16_t*>(identifier_swapped + 6);
196 124 : *data3 = htons(*data3);
197 :
198 124 : int buffer_idx = 0;
199 2108 : for (unsigned int idx = 0;
200 : (buffer_idx < buffer_length) && (idx < kMDGUIDSize);
201 : ++idx) {
202 1984 : int hi = (identifier_swapped[idx] >> 4) & 0x0F;
203 1984 : int lo = (identifier_swapped[idx]) & 0x0F;
204 :
205 1984 : if (idx == 4 || idx == 6 || idx == 8 || idx == 10)
206 496 : buffer[buffer_idx++] = '-';
207 :
208 1984 : buffer[buffer_idx++] = (hi >= 10) ? 'A' + hi - 10 : '0' + hi;
209 1984 : buffer[buffer_idx++] = (lo >= 10) ? 'A' + lo - 10 : '0' + lo;
210 : }
211 :
212 : // NULL terminate
213 124 : buffer[(buffer_idx < buffer_length) ? buffer_idx : buffer_idx - 1] = 0;
214 124 : }
215 :
216 : } // namespace google_breakpad
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