1/* Copyright (C) 1999-2019 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 <http://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) \
29do \
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. */
41int
42process_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 ElfW(Addr) loadaddr;
49 unsigned int dynamic_addr;
50 size_t dynamic_size;
51 char *program_interpreter;
52
53 ElfW(Ehdr) *elf_header;
54 ElfW(Phdr) *elf_pheader, *segment;
55 ElfW(Dyn) *dynamic_segment, *dyn_entry;
56 char *dynamic_strings;
57
58 elf_header = (ElfW(Ehdr) *) file_contents;
59 *osversion = 0;
60
61 if (elf_header->e_ident [EI_CLASS] != ElfW (CLASS))
62 {
63 if (opt_verbose)
64 {
65 if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
66 error (0, 0, _("%s is a 32 bit ELF file.\n"), file_name);
67 else if (elf_header->e_ident [EI_CLASS] == ELFCLASS64)
68 error (0, 0, _("%s is a 64 bit ELF file.\n"), file_name);
69 else
70 error (0, 0, _("Unknown ELFCLASS in file %s.\n"), file_name);
71 }
72 return 1;
73 }
74
75 if (elf_header->e_type != ET_DYN)
76 {
77 error (0, 0, _("%s is not a shared object file (Type: %d).\n"), file_name,
78 elf_header->e_type);
79 return 1;
80 }
81
82 /* Get information from elf program header. */
83 elf_pheader = (ElfW(Phdr) *) (elf_header->e_phoff + file_contents);
84 check_ptr (elf_pheader);
85
86 /* The library is an elf library, now search for soname and
87 libc5/libc6. */
88 *flag = FLAG_ELF;
89
90 loadaddr = -1;
91 dynamic_addr = 0;
92 dynamic_size = 0;
93 program_interpreter = NULL;
94 for (i = 0, segment = elf_pheader;
95 i < elf_header->e_phnum; i++, segment++)
96 {
97 check_ptr (segment);
98
99 switch (segment->p_type)
100 {
101 case PT_LOAD:
102 if (loadaddr == (ElfW(Addr)) -1)
103 loadaddr = segment->p_vaddr - segment->p_offset;
104 break;
105
106 case PT_DYNAMIC:
107 if (dynamic_addr)
108 error (0, 0, _("more than one dynamic segment\n"));
109
110 dynamic_addr = segment->p_offset;
111 dynamic_size = segment->p_filesz;
112 break;
113
114 case PT_INTERP:
115 program_interpreter = (char *) (file_contents + segment->p_offset);
116 check_ptr (program_interpreter);
117
118 /* Check if this is enough to classify the binary. */
119 for (j = 0; j < sizeof (interpreters) / sizeof (interpreters [0]);
120 ++j)
121 if (strcmp (program_interpreter, interpreters[j].soname) == 0)
122 {
123 *flag = interpreters[j].flag;
124 break;
125 }
126 break;
127
128 case PT_NOTE:
129 if (!*osversion && segment->p_filesz >= 32 && segment->p_align >= 4)
130 {
131 ElfW(Word) *abi_note = (ElfW(Word) *) (file_contents
132 + segment->p_offset);
133 ElfW(Addr) size = segment->p_filesz;
134 /* NB: Some PT_NOTE segment may have alignment value of 0
135 or 1. gABI specifies that PT_NOTE segments should be
136 aligned to 4 bytes in 32-bit objects and to 8 bytes in
137 64-bit objects. As a Linux extension, we also support
138 4 byte alignment in 64-bit objects. If p_align is less
139 than 4, we treate alignment as 4 bytes since some note
140 segments have 0 or 1 byte alignment. */
141 ElfW(Addr) align = segment->p_align;
142 if (align < 4)
143 align = 4;
144 else if (align != 4 && align != 8)
145 continue;
146
147 while (abi_note [0] != 4 || abi_note [1] != 16
148 || abi_note [2] != 1
149 || memcmp (abi_note + 3, "GNU", 4) != 0)
150 {
151 ElfW(Addr) note_size
152 = ELF_NOTE_NEXT_OFFSET (abi_note[0], abi_note[1],
153 align);
154
155 if (size - 32 < note_size || note_size == 0)
156 {
157 size = 0;
158 break;
159 }
160 size -= note_size;
161 abi_note = (void *) abi_note + note_size;
162 }
163
164 if (size == 0)
165 break;
166
167 *osversion = (abi_note [4] << 24) |
168 ((abi_note [5] & 0xff) << 16) |
169 ((abi_note [6] & 0xff) << 8) |
170 (abi_note [7] & 0xff);
171 }
172 break;
173
174 default:
175 break;
176 }
177
178 }
179 if (loadaddr == (ElfW(Addr)) -1)
180 {
181 /* Very strange. */
182 loadaddr = 0;
183 }
184
185 /* Now we can read the dynamic sections. */
186 if (dynamic_size == 0)
187 return 1;
188
189 dynamic_segment = (ElfW(Dyn) *) (file_contents + dynamic_addr);
190 check_ptr (dynamic_segment);
191
192 /* Find the string table. */
193 dynamic_strings = NULL;
194 for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL;
195 ++dyn_entry)
196 {
197 check_ptr (dyn_entry);
198 if (dyn_entry->d_tag == DT_STRTAB)
199 {
200 dynamic_strings = (char *) (file_contents + dyn_entry->d_un.d_val - loadaddr);
201 check_ptr (dynamic_strings);
202 break;
203 }
204 }
205
206 if (dynamic_strings == NULL)
207 return 1;
208
209 /* Now read the DT_NEEDED and DT_SONAME entries. */
210 for (dyn_entry = dynamic_segment; dyn_entry->d_tag != DT_NULL;
211 ++dyn_entry)
212 {
213 if (dyn_entry->d_tag == DT_NEEDED || dyn_entry->d_tag == DT_SONAME)
214 {
215 char *name = dynamic_strings + dyn_entry->d_un.d_val;
216 check_ptr (name);
217
218 if (dyn_entry->d_tag == DT_NEEDED)
219 {
220
221 if (*flag == FLAG_ELF)
222 {
223 /* Check if this is enough to classify the binary. */
224 for (j = 0;
225 j < sizeof (known_libs) / sizeof (known_libs [0]);
226 ++j)
227 if (strcmp (name, known_libs [j].soname) == 0)
228 {
229 *flag = known_libs [j].flag;
230 break;
231 }
232 }
233 }
234
235 else if (dyn_entry->d_tag == DT_SONAME)
236 *soname = xstrdup (name);
237
238 /* Do we have everything we need? */
239 if (*soname && *flag != FLAG_ELF)
240 return 0;
241 }
242 }
243
244 return 0;
245}
246