1 | /* Copyright (C) 1999-2020 Free Software Foundation, Inc. |
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 |
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. |
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 |
14 | Lesser General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, see |
18 | <https://www.gnu.org/licenses/>. */ |
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 | |
25 | /* check_ptr checks that a pointer is in the mmaped file and doesn't |
26 | point outside it. */ |
27 | #undef check_ptr |
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); |
39 | |
40 | /* Returns 0 if everything is ok, != 0 in case of error. */ |
41 | int |
42 | process_elf_file (const char *file_name, const char *lib, int *flag, |
43 | unsigned int *osversion, char **soname, void *file_contents, |
44 | size_t file_length) |
45 | { |
46 | int i; |
47 | unsigned int j; |
48 | unsigned int dynamic_addr; |
49 | size_t dynamic_size; |
50 | char *program_interpreter; |
51 | |
52 | ElfW(Ehdr) *; |
53 | ElfW(Phdr) *, *segment; |
54 | ElfW(Dyn) *dynamic_segment, *dyn_entry; |
55 | char *dynamic_strings; |
56 | |
57 | elf_header = (ElfW(Ehdr) *) file_contents; |
58 | *osversion = 0; |
59 | |
60 | if (elf_header->e_ident [EI_CLASS] != ElfW (CLASS)) |
61 | { |
62 | if (opt_verbose) |
63 | { |
64 | if (elf_header->e_ident [EI_CLASS] == ELFCLASS32) |
65 | error (0, 0, _("%s is a 32 bit ELF file.\n" ), file_name); |
66 | else if (elf_header->e_ident [EI_CLASS] == ELFCLASS64) |
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 | } |
80 | |
81 | /* Get information from elf program header. */ |
82 | elf_pheader = (ElfW(Phdr) *) (elf_header->e_phoff + file_contents); |
83 | check_ptr (elf_pheader); |
84 | |
85 | /* The library is an elf library, now search for soname and |
86 | libc5/libc6. */ |
87 | *flag = FLAG_ELF; |
88 | |
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 | { |
95 | check_ptr (segment); |
96 | |
97 | switch (segment->p_type) |
98 | { |
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; |
106 | |
107 | case PT_INTERP: |
108 | program_interpreter = (char *) (file_contents + segment->p_offset); |
109 | check_ptr (program_interpreter); |
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; |
120 | |
121 | case PT_NOTE: |
122 | if (!*osversion && segment->p_filesz >= 32 && segment->p_align >= 4) |
123 | { |
124 | ElfW(Word) *abi_note = (ElfW(Word) *) (file_contents |
125 | + segment->p_offset); |
126 | ElfW(Addr) size = segment->p_filesz; |
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; |
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 | { |
144 | ElfW(Addr) note_size |
145 | = ELF_NOTE_NEXT_OFFSET (abi_note[0], abi_note[1], |
146 | align); |
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 | |
160 | *osversion = ((abi_note [4] << 24) |
161 | | ((abi_note [5] & 0xff) << 16) |
162 | | ((abi_note [6] & 0xff) << 8) |
163 | | (abi_note [7] & 0xff)); |
164 | } |
165 | break; |
166 | |
167 | default: |
168 | break; |
169 | } |
170 | |
171 | } |
172 | |
173 | /* Now we can read the dynamic sections. */ |
174 | if (dynamic_size == 0) |
175 | return 1; |
176 | |
177 | dynamic_segment = (ElfW(Dyn) *) (file_contents + dynamic_addr); |
178 | check_ptr (dynamic_segment); |
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 | { |
185 | check_ptr (dyn_entry); |
186 | if (dyn_entry->d_tag == DT_STRTAB) |
187 | { |
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); |
211 | check_ptr (dynamic_strings); |
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; |
226 | check_ptr (name); |
227 | |
228 | if (dyn_entry->d_tag == DT_NEEDED) |
229 | { |
230 | |
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); |
247 | |
248 | /* Do we have everything we need? */ |
249 | if (*soname && *flag != FLAG_ELF) |
250 | return 0; |
251 | } |
252 | } |
253 | |
254 | return 0; |
255 | } |
256 | |