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 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published
8 by the Free Software Foundation; version 2 of the License, or
9 (at your option) any later version.
10
11 This program 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
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, see <https://www.gnu.org/licenses/>. */
18
19/* The code in this file and in readelflib is a heavily simplified
20 version of the readelf program that's part of the current binutils
21 development version. Besides the simplification, it has also been
22 modified to read some other file formats. */
23
24#include <a.out.h>
25#include <elf.h>
26#include <error.h>
27#include <libintl.h>
28#include <link.h>
29#include <stdio.h>
30#include <string.h>
31#include <unistd.h>
32#include <sys/mman.h>
33#include <sys/param.h>
34#include <sys/stat.h>
35#include <gnu/lib-names.h>
36
37#include <ldconfig.h>
38
39#define Elf32_CLASS ELFCLASS32
40#define Elf64_CLASS ELFCLASS64
41
42struct known_names
43{
44 const char *soname;
45 int flag;
46};
47
48static struct known_names interpreters[] =
49{
50 { "/lib/" LD_SO, FLAG_ELF_LIBC6 },
51#ifdef SYSDEP_KNOWN_INTERPRETER_NAMES
52 SYSDEP_KNOWN_INTERPRETER_NAMES
53#endif
54};
55
56static struct known_names known_libs[] =
57{
58 { LIBC_SO, FLAG_ELF_LIBC6 },
59 { LIBM_SO, FLAG_ELF_LIBC6 },
60#ifdef SYSDEP_KNOWN_LIBRARY_NAMES
61 SYSDEP_KNOWN_LIBRARY_NAMES
62#endif
63};
64
65
66/* Check if string corresponds to a GDB Python file. */
67static bool
68is_gdb_python_file (const char *name)
69{
70 size_t len = strlen (name);
71 return len > 7 && strcmp (name + len - 7, "-gdb.py") == 0;
72}
73
74/* Returns 0 if everything is ok, != 0 in case of error. */
75int
76process_file (const char *real_file_name, const char *file_name,
77 const char *lib, int *flag, unsigned int *osversion,
78 char **soname, int is_link, struct stat64 *stat_buf)
79{
80 FILE *file;
81 struct stat64 statbuf;
82 void *file_contents;
83 int ret;
84 ElfW(Ehdr) *elf_header;
85 struct exec *aout_header;
86
87 ret = 0;
88 *flag = FLAG_ANY;
89 *soname = NULL;
90
91 file = fopen (real_file_name, "rb");
92 if (file == NULL)
93 {
94 /* No error for stale symlink. */
95 if (is_link && strstr (file_name, ".so") != NULL)
96 return 1;
97 error (0, 0, _("Input file %s not found.\n"), file_name);
98 return 1;
99 }
100
101 if (fstat64 (fileno (file), &statbuf) < 0)
102 {
103 error (0, 0, _("Cannot fstat file %s.\n"), file_name);
104 fclose (file);
105 return 1;
106 }
107
108 /* Check that the file is large enough so that we can access the
109 information. We're only checking the size of the headers here. */
110 if ((size_t) statbuf.st_size < sizeof (struct exec)
111 || (size_t) statbuf.st_size < sizeof (ElfW(Ehdr)))
112 {
113 if (statbuf.st_size == 0)
114 error (0, 0, _("File %s is empty, not checked."), file_name);
115 else
116 {
117 char buf[SELFMAG];
118 size_t n = MIN (statbuf.st_size, SELFMAG);
119 if (fread (buf, n, 1, file) == 1 && memcmp (buf, ELFMAG, n) == 0)
120 error (0, 0, _("File %s is too small, not checked."), file_name);
121 }
122 fclose (file);
123 return 1;
124 }
125
126 file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
127 fileno (file), 0);
128 if (file_contents == MAP_FAILED)
129 {
130 error (0, 0, _("Cannot mmap file %s.\n"), file_name);
131 fclose (file);
132 return 1;
133 }
134
135 /* First check if this is an aout file. */
136 aout_header = (struct exec *) file_contents;
137 if (N_MAGIC (*aout_header) == ZMAGIC
138#ifdef QMAGIC /* Linuxism. */
139 || N_MAGIC (*aout_header) == QMAGIC
140#endif
141 )
142 {
143 /* Aout files don't have a soname, just return the name
144 including the major number. */
145 char *copy, *major, *dot;
146 copy = xstrdup (lib);
147 major = strstr (copy, ".so.");
148 if (major)
149 {
150 dot = strstr (major + 4, ".");
151 if (dot)
152 *dot = '\0';
153 }
154 *soname = copy;
155 *flag = FLAG_LIBC4;
156 goto done;
157 }
158
159 elf_header = (ElfW(Ehdr) *) file_contents;
160 if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
161 {
162 /* The file is neither ELF nor aout. Check if it's a linker
163 script, like libc.so - otherwise complain. Only search the
164 beginning of the file. */
165 size_t len = MIN (statbuf.st_size, 512);
166 if (memmem (file_contents, len, "GROUP", 5) == NULL
167 && memmem (file_contents, len, "GNU ld script", 13) == NULL
168 && !is_gdb_python_file (file_name))
169 error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
170 file_name);
171 ret = 1;
172 }
173 /* Libraries have to be shared object files. */
174 else if (elf_header->e_type != ET_DYN)
175 ret = 1;
176 else if (process_elf_file (file_name, lib, flag, osversion, soname,
177 file_contents, statbuf.st_size))
178 ret = 1;
179
180 done:
181 /* Clean up allocated memory and resources. */
182 munmap (file_contents, statbuf.st_size);
183 fclose (file);
184
185 *stat_buf = statbuf;
186 return ret;
187}
188
189/* Returns made up soname if lib doesn't have explicit DT_SONAME. */
190
191char *
192implicit_soname (const char *lib, int flag)
193{
194 char *soname = xstrdup (lib);
195
196 if ((flag & FLAG_TYPE_MASK) != FLAG_LIBC4)
197 return soname;
198
199 /* Aout files don't have a soname, just return the name
200 including the major number. */
201 char *major = strstr (soname, ".so.");
202 if (major)
203 {
204 char *dot = strstr (major + 4, ".");
205 if (dot)
206 *dot = '\0';
207 }
208 return soname;
209}
210
211/* Get architecture specific version of process_elf_file. */
212#include <readelflib.c>
213