1/* Create an ELF file with all the DT_* flags set.
2   Copyright (C) 2011 Red Hat, Inc.
3   This file is part of elfutils.
4   Written by Marek Polacek <mpolacek@redhat.com>, 2011.
5
6   This file is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3 of the License, or
9   (at your option) any later version.
10
11   elfutils is distributed in the hope that it will be useful, but
12   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 <http://www.gnu.org/licenses/>.  */
18
19#ifdef HAVE_CONFIG_H
20# include <config.h>
21#endif
22
23#include ELFUTILS_HEADER(ebl)
24#include <elf.h>
25#include <gelf.h>
26#include <fcntl.h>
27#include <libelf.h>
28#include <stdio.h>
29#include <stdio_ext.h>
30#include <stdint.h>
31#include <stdbool.h>
32#include <stdlib.h>
33#include <string.h>
34#include <unistd.h>
35
36
37int
38main (void)
39{
40  static const char fname[] = "testfile-alldts";
41  struct Ebl_Strtab *shst;
42  struct Ebl_Strent *dynscn;
43  struct Ebl_Strent *shstrtabse;
44  const Elf32_Sword dtflags[] =
45    {
46      DT_NULL, DT_NEEDED, DT_PLTRELSZ, DT_PLTGOT,
47      DT_HASH, DT_STRTAB, DT_SYMTAB, DT_RELA,
48      DT_RELASZ, DT_RELAENT, DT_STRSZ, DT_SYMENT,
49      DT_INIT, DT_FINI, DT_SONAME, DT_RPATH,
50      DT_SYMBOLIC, DT_REL, DT_RELSZ, DT_RELENT,
51      DT_PLTREL, DT_DEBUG, DT_TEXTREL, DT_JMPREL,
52      DT_BIND_NOW, DT_INIT_ARRAY, DT_FINI_ARRAY,
53      DT_INIT_ARRAYSZ, DT_FINI_ARRAYSZ, DT_RUNPATH,
54      DT_FLAGS, DT_ENCODING, DT_PREINIT_ARRAY,
55      DT_PREINIT_ARRAYSZ, DT_VERSYM, DT_GNU_PRELINKED,
56      DT_GNU_CONFLICTSZ, DT_GNU_LIBLISTSZ, DT_CHECKSUM,
57      DT_PLTPADSZ, DT_MOVEENT, DT_MOVESZ, DT_FEATURE_1,
58      DT_POSFLAG_1, DT_SYMINSZ, DT_SYMINENT, DT_GNU_HASH,
59      DT_TLSDESC_PLT, DT_TLSDESC_GOT, DT_GNU_CONFLICT,
60      DT_GNU_LIBLIST, DT_CONFIG, DT_DEPAUDIT, DT_AUDIT,
61      DT_PLTPAD, DT_MOVETAB, DT_SYMINFO, DT_RELACOUNT,
62      DT_RELCOUNT, DT_FLAGS_1, DT_VERDEF, DT_VERDEFNUM,
63      DT_VERNEED, DT_VERNEEDNUM, DT_AUXILIARY, DT_FILTER
64    };
65  const int ndtflags = sizeof (dtflags) / sizeof (dtflags[0]);
66
67  /* We use no threads here which can interfere with handling a stream.  */
68  (void) __fsetlocking (stdout, FSETLOCKING_BYCALLER);
69
70  /* Open the file.  */
71  int fd = open (fname, O_RDWR | O_CREAT | O_TRUNC, 0666);
72  if (fd == -1)
73    {
74      printf ("cannot open `%s': %m\n", fname);
75      return 1;
76    }
77
78  /* Tell the library which version are we expecting.  */
79  elf_version (EV_CURRENT);
80
81  /* Create an ELF descriptor.  */
82  Elf *elf = elf_begin (fd, ELF_C_WRITE, NULL);
83  if (elf == NULL)
84    {
85      printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
86      return 1;
87    }
88
89  /* Create an ELF header.  */
90  Elf32_Ehdr *ehdr = elf32_newehdr (elf);
91  if (ehdr == NULL)
92    {
93      printf ("cannot create ELF header: %s\n", elf_errmsg (-1));
94      return 1;
95    }
96
97  ehdr->e_ident[0] = 42;
98  ehdr->e_ident[5] = 1;
99  ehdr->e_ident[6] = 2;
100  ehdr->e_type = ET_EXEC;
101  ehdr->e_machine = EM_386;
102  ehdr->e_version = 1;
103  ehdr->e_ehsize = 1;
104  ehdr->e_shnum = 3;
105
106  elf_flagehdr (elf, ELF_C_SET, ELF_F_DIRTY);
107
108  /* Create the program headers.  */
109  Elf32_Phdr *phdr = elf32_newphdr (elf, 2);
110  if (phdr == NULL)
111    {
112      printf ("cannot create program headers: %s\n", elf_errmsg (-1));
113      return 1;
114    }
115
116  phdr[0].p_type = PT_PHDR;
117  phdr[1].p_type = PT_DYNAMIC;
118
119  elf_flagphdr (elf, ELF_C_SET, ELF_F_DIRTY);
120  shst = ebl_strtabinit (true);
121
122  /* Create the .dynamic section.  */
123  Elf_Scn *scn = elf_newscn (elf);
124  if (scn == NULL)
125    {
126      printf ("cannot create DYNAMIC section: %s\n", elf_errmsg (-1));
127      return 1;
128    }
129
130  Elf32_Shdr *shdr = elf32_getshdr (scn);
131  if (shdr == NULL)
132    {
133      printf ("cannot get header for DYNAMIC section: %s\n", elf_errmsg (-1));
134      return 1;
135    }
136
137  dynscn = ebl_strtabadd (shst, ".dynamic", 0);
138
139  /* We'll need to know the section offset.  But this will be set up
140     by elf_update later, so for now just store the address.  */
141  const Elf32_Off *const dynscn_offset = &shdr->sh_offset;
142  shdr->sh_type = SHT_DYNAMIC;
143  shdr->sh_flags = SHF_ALLOC | SHF_WRITE;
144  shdr->sh_link = SHN_UNDEF;
145  shdr->sh_info = SHN_UNDEF;
146  /* This section will start here.  */
147  shdr->sh_addr = 0x1a0;
148
149  /* Create new section data.  */
150  Elf_Data *data = elf_newdata (scn);
151  if (data == NULL)
152    {
153      printf ("cannot create data for DYNAMIC section: %s\n", elf_errmsg (-1));
154      return 1;
155    }
156
157  /* Allocate memory for all the .dynamic entries.  */
158  Elf32_Dyn *dyn = malloc (ndtflags * sizeof (Elf32_Dyn));
159  if (dyn == NULL)
160    {
161      printf ("malloc failed: %m\n");
162      return 1;
163    }
164
165  /* Now write all the DT_* flags.  */
166  for (int i = 0; i < ndtflags; ++i)
167    {
168      dyn[i].d_tag = dtflags[i];
169      dyn[i].d_un.d_val = 0xdeadbeef;
170    }
171
172  /* Set the pointer to allocated memory.  */
173  data->d_buf = dyn;
174  data->d_type = ELF_T_DYN;
175  data->d_version = EV_CURRENT;
176  data->d_size = ndtflags * sizeof (Elf32_Dyn);
177  data->d_align = 0x8;
178
179  /* Create .shstrtab section.  */
180  scn = elf_newscn (elf);
181  if (scn == NULL)
182    {
183      printf ("cannot create SHSTRTAB section: %s\n", elf_errmsg (-1));
184      return 1;
185    }
186
187  shdr = elf32_getshdr (scn);
188  if (shdr == NULL)
189    {
190      printf ("cannot get header for SHSTRTAB section: %s\n", elf_errmsg (-1));
191      return 1;
192    }
193
194  shstrtabse = ebl_strtabadd (shst, ".shstrtab", 0);
195
196  shdr->sh_type = SHT_STRTAB;
197  shdr->sh_flags = 0;
198  shdr->sh_addr = 0;
199  shdr->sh_link = SHN_UNDEF;
200  shdr->sh_info = SHN_UNDEF;
201  shdr->sh_entsize = 1;
202
203  /* We have to store the section index in the ELF header.  */
204  ehdr->e_shstrndx = elf_ndxscn (scn);
205
206  data = elf_newdata (scn);
207  if (data == NULL)
208    {
209      printf ("cannot create data SHSTRTAB section: %s\n", elf_errmsg (-1));
210      return 1;
211    }
212
213  /* No more sections, finalize the section header string table.  */
214  ebl_strtabfinalize (shst, data);
215
216  elf32_getshdr (elf_getscn (elf, 1))->sh_name = ebl_strtaboffset (dynscn);
217  shdr->sh_name = ebl_strtaboffset (shstrtabse);
218
219  /* Let the library compute the internal structure information.  */
220  if (elf_update (elf, ELF_C_NULL) < 0)
221    {
222      printf ("failure in elf_update(NULL): %s\n", elf_errmsg (-1));
223      return 1;
224    }
225
226  ehdr = elf32_getehdr (elf);
227
228  phdr[0].p_offset = ehdr->e_phoff;
229  phdr[0].p_vaddr = ehdr->e_phoff;
230  phdr[0].p_paddr = ehdr->e_phoff;
231  phdr[0].p_flags = PF_R | PF_X;
232  phdr[0].p_filesz = ehdr->e_phnum * elf32_fsize (ELF_T_PHDR, 1, EV_CURRENT);
233  phdr[0].p_memsz = ehdr->e_phnum * elf32_fsize (ELF_T_PHDR, 1, EV_CURRENT);
234  phdr[0].p_align = sizeof (Elf32_Word);
235
236  phdr[1].p_flags = PF_W | PF_R;
237  phdr[1].p_offset = *dynscn_offset;
238  /* Set up the start of this segment to equal start address of the
239     .dynamic section.  */
240  phdr[1].p_vaddr = 0x1a0;
241  phdr[1].p_paddr = 0x1a0;
242  phdr[1].p_align = 2 * sizeof (Elf32_Word);
243  phdr[1].p_filesz = ndtflags * sizeof (Elf32_Dyn);
244  phdr[1].p_memsz = ndtflags * sizeof (Elf32_Dyn);
245
246  /* Write out the file.  */
247  if (elf_update (elf, ELF_C_WRITE) < 0)
248    {
249      printf ("failure in elf_update(WRITE): %s\n", elf_errmsg (-1));
250      return 1;
251    }
252
253  /* We don't need the string table anymore.  */
254  ebl_strtabfree (shst);
255
256  /* And the data allocated in the .shstrtab section.  */
257  free (data->d_buf);
258
259  /* And the dynamic entries.  */
260  free (dyn);
261
262  /* All done.  */
263  if (elf_end (elf) != 0)
264    {
265      printf ("failure in elf_end: %s\n", elf_errmsg (-1));
266      return 1;
267    }
268
269  return 0;
270}
271