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2b778ceb | 1 | /* Copyright (C) 1999-2021 Free Software Foundation, Inc. |
591e1ffb UD |
2 | This file is part of the GNU C Library. |
3 | Contributed by Andreas Jaeger <aj@suse.de>, 1999 and | |
4 | Jakub Jelinek <jakub@redhat.com>, 1999. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
591e1ffb UD |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
591e1ffb | 15 | |
41bdb6e2 | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 17 | License along with the GNU C Library; if not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
591e1ffb UD |
19 | |
20 | /* This code is a heavily simplified version of the readelf program | |
21 | that's part of the current binutils development version. For architectures | |
22 | which need to handle both 32bit and 64bit ELF libraries, this file is | |
23 | included twice for each arch size. */ | |
24 | ||
dc95d158 AJ |
25 | /* check_ptr checks that a pointer is in the mmaped file and doesn't |
26 | point outside it. */ | |
a0f5c800 | 27 | #undef check_ptr |
dc95d158 AJ |
28 | #define check_ptr(ptr) \ |
29 | do \ | |
30 | { \ | |
31 | if ((void *)(ptr) < file_contents \ | |
32 | || (void *)(ptr) > (file_contents+file_length)) \ | |
33 | { \ | |
34 | error (0, 0, _("file %s is truncated\n"), file_name); \ | |
35 | return 1; \ | |
36 | } \ | |
37 | } \ | |
38 | while (0); | |
c98d82db | 39 | |
591e1ffb UD |
40 | /* Returns 0 if everything is ok, != 0 in case of error. */ |
41 | int | |
dc95d158 | 42 | process_elf_file (const char *file_name, const char *lib, int *flag, |
a986484f UD |
43 | unsigned int *osversion, char **soname, void *file_contents, |
44 | size_t file_length) | |
591e1ffb UD |
45 | { |
46 | int i; | |
47 | unsigned int j; | |
591e1ffb UD |
48 | unsigned int dynamic_addr; |
49 | size_t dynamic_size; | |
50 | char *program_interpreter; | |
c98d82db | 51 | |
591e1ffb UD |
52 | ElfW(Ehdr) *elf_header; |
53 | ElfW(Phdr) *elf_pheader, *segment; | |
54 | ElfW(Dyn) *dynamic_segment, *dyn_entry; | |
c98d82db | 55 | char *dynamic_strings; |
591e1ffb UD |
56 | |
57 | elf_header = (ElfW(Ehdr) *) file_contents; | |
a986484f | 58 | *osversion = 0; |
591e1ffb UD |
59 | |
60 | if (elf_header->e_ident [EI_CLASS] != ElfW (CLASS)) | |
61 | { | |
62 | if (opt_verbose) | |
63 | { | |
63fb40b3 | 64 | if (elf_header->e_ident [EI_CLASS] == ELFCLASS32) |
591e1ffb | 65 | error (0, 0, _("%s is a 32 bit ELF file.\n"), file_name); |
63fb40b3 | 66 | else if (elf_header->e_ident [EI_CLASS] == ELFCLASS64) |
591e1ffb UD |
67 | error (0, 0, _("%s is a 64 bit ELF file.\n"), file_name); |
68 | else | |
69 | error (0, 0, _("Unknown ELFCLASS in file %s.\n"), file_name); | |
70 | } | |
71 | return 1; | |
72 | } | |
73 | ||
74 | if (elf_header->e_type != ET_DYN) | |
75 | { | |
76 | error (0, 0, _("%s is not a shared object file (Type: %d).\n"), file_name, | |
77 | elf_header->e_type); | |
78 | return 1; | |
79 | } | |
c98d82db | 80 | |
591e1ffb UD |
81 | /* Get information from elf program header. */ |
82 | elf_pheader = (ElfW(Phdr) *) (elf_header->e_phoff + file_contents); | |
dc95d158 | 83 | check_ptr (elf_pheader); |
591e1ffb UD |
84 | |
85 | /* The library is an elf library, now search for soname and | |
86 | libc5/libc6. */ | |
87 | *flag = FLAG_ELF; | |
c98d82db | 88 | |
591e1ffb UD |
89 | dynamic_addr = 0; |
90 | dynamic_size = 0; | |
91 | program_interpreter = NULL; | |
92 | for (i = 0, segment = elf_pheader; | |
93 | i < elf_header->e_phnum; i++, segment++) | |
94 | { | |
dc95d158 AJ |
95 | check_ptr (segment); |
96 | ||
591e1ffb UD |
97 | switch (segment->p_type) |
98 | { | |
591e1ffb UD |
99 | case PT_DYNAMIC: |
100 | if (dynamic_addr) | |
101 | error (0, 0, _("more than one dynamic segment\n")); | |
102 | ||
103 | dynamic_addr = segment->p_offset; | |
104 | dynamic_size = segment->p_filesz; | |
105 | break; | |
a986484f | 106 | |
591e1ffb UD |
107 | case PT_INTERP: |
108 | program_interpreter = (char *) (file_contents + segment->p_offset); | |
dc95d158 | 109 | check_ptr (program_interpreter); |
591e1ffb UD |
110 | |
111 | /* Check if this is enough to classify the binary. */ | |
112 | for (j = 0; j < sizeof (interpreters) / sizeof (interpreters [0]); | |
113 | ++j) | |
114 | if (strcmp (program_interpreter, interpreters[j].soname) == 0) | |
115 | { | |
116 | *flag = interpreters[j].flag; | |
117 | break; | |
118 | } | |
119 | break; | |
a986484f UD |
120 | |
121 | case PT_NOTE: | |
0e508a6e | 122 | if (!*osversion && segment->p_filesz >= 32 && segment->p_align >= 4) |
a986484f UD |
123 | { |
124 | ElfW(Word) *abi_note = (ElfW(Word) *) (file_contents | |
125 | + segment->p_offset); | |
0e508a6e | 126 | ElfW(Addr) size = segment->p_filesz; |
8d81ce0c L |
127 | /* NB: Some PT_NOTE segment may have alignment value of 0 |
128 | or 1. gABI specifies that PT_NOTE segments should be | |
129 | aligned to 4 bytes in 32-bit objects and to 8 bytes in | |
130 | 64-bit objects. As a Linux extension, we also support | |
131 | 4 byte alignment in 64-bit objects. If p_align is less | |
132 | than 4, we treate alignment as 4 bytes since some note | |
133 | segments have 0 or 1 byte alignment. */ | |
134 | ElfW(Addr) align = segment->p_align; | |
135 | if (align < 4) | |
136 | align = 4; | |
137 | else if (align != 4 && align != 8) | |
138 | continue; | |
0e508a6e UD |
139 | |
140 | while (abi_note [0] != 4 || abi_note [1] != 16 | |
141 | || abi_note [2] != 1 | |
142 | || memcmp (abi_note + 3, "GNU", 4) != 0) | |
143 | { | |
8d81ce0c L |
144 | ElfW(Addr) note_size |
145 | = ELF_NOTE_NEXT_OFFSET (abi_note[0], abi_note[1], | |
146 | align); | |
0e508a6e UD |
147 | |
148 | if (size - 32 < note_size || note_size == 0) | |
149 | { | |
150 | size = 0; | |
151 | break; | |
152 | } | |
153 | size -= note_size; | |
154 | abi_note = (void *) abi_note + note_size; | |
155 | } | |
156 | ||
157 | if (size == 0) | |
158 | break; | |
159 | ||
34a5a146 JM |
160 | *osversion = ((abi_note [4] << 24) |
161 | | ((abi_note [5] & 0xff) << 16) | |
162 | | ((abi_note [6] & 0xff) << 8) | |
163 | | (abi_note [7] & 0xff)); | |
a986484f UD |
164 | } |
165 | break; | |
166 | ||
591e1ffb UD |
167 | default: |
168 | break; | |
169 | } | |
c98d82db | 170 | |
591e1ffb | 171 | } |
591e1ffb UD |
172 | |
173 | /* Now we can read the dynamic sections. */ | |
174 | if (dynamic_size == 0) | |
175 | return 1; | |
c98d82db | 176 | |
591e1ffb | 177 | dynamic_segment = (ElfW(Dyn) *) (file_contents + dynamic_addr); |
dc95d158 | 178 | check_ptr (dynamic_segment); |
591e1ffb UD |
179 | |
180 | /* Find the string table. */ | |
181 | dynamic_strings = NULL; | |
182 | for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL; | |
183 | ++dyn_entry) | |
184 | { | |
dc95d158 | 185 | check_ptr (dyn_entry); |
591e1ffb UD |
186 | if (dyn_entry->d_tag == DT_STRTAB) |
187 | { | |
58e8f5fd AS |
188 | /* Find the file offset of the segment containing the dynamic |
189 | string table. */ | |
190 | ElfW(Off) loadoff = -1; | |
191 | for (i = 0, segment = elf_pheader; | |
192 | i < elf_header->e_phnum; i++, segment++) | |
193 | { | |
194 | if (segment->p_type == PT_LOAD | |
195 | && dyn_entry->d_un.d_val >= segment->p_vaddr | |
196 | && (dyn_entry->d_un.d_val - segment->p_vaddr | |
197 | < segment->p_filesz)) | |
198 | { | |
199 | loadoff = segment->p_vaddr - segment->p_offset; | |
200 | break; | |
201 | } | |
202 | } | |
203 | if (loadoff == (ElfW(Off)) -1) | |
204 | { | |
205 | /* Very strange. */ | |
206 | loadoff = 0; | |
207 | } | |
208 | ||
209 | dynamic_strings = (char *) (file_contents + dyn_entry->d_un.d_val | |
210 | - loadoff); | |
dc95d158 | 211 | check_ptr (dynamic_strings); |
591e1ffb UD |
212 | break; |
213 | } | |
214 | } | |
215 | ||
216 | if (dynamic_strings == NULL) | |
217 | return 1; | |
218 | ||
219 | /* Now read the DT_NEEDED and DT_SONAME entries. */ | |
220 | for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL; | |
221 | ++dyn_entry) | |
222 | { | |
223 | if (dyn_entry->d_tag == DT_NEEDED || dyn_entry->d_tag == DT_SONAME) | |
224 | { | |
225 | char *name = dynamic_strings + dyn_entry->d_un.d_val; | |
dc95d158 | 226 | check_ptr (name); |
591e1ffb UD |
227 | |
228 | if (dyn_entry->d_tag == DT_NEEDED) | |
229 | { | |
c98d82db | 230 | |
591e1ffb UD |
231 | if (*flag == FLAG_ELF) |
232 | { | |
233 | /* Check if this is enough to classify the binary. */ | |
234 | for (j = 0; | |
235 | j < sizeof (known_libs) / sizeof (known_libs [0]); | |
236 | ++j) | |
237 | if (strcmp (name, known_libs [j].soname) == 0) | |
238 | { | |
239 | *flag = known_libs [j].flag; | |
240 | break; | |
241 | } | |
242 | } | |
243 | } | |
244 | ||
245 | else if (dyn_entry->d_tag == DT_SONAME) | |
246 | *soname = xstrdup (name); | |
c98d82db | 247 | |
591e1ffb UD |
248 | /* Do we have everything we need? */ |
249 | if (*soname && *flag != FLAG_ELF) | |
250 | return 0; | |
251 | } | |
252 | } | |
253 | ||
591e1ffb UD |
254 | return 0; |
255 | } |