1/* Compute simple checksum from permanent parts of the ELF file.
2   Copyright (C) 2002, 2003, 2004, 2005, 2009 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2002.
5
6   Red Hat elfutils is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by the
8   Free Software Foundation; version 2 of the License.
9
10   Red Hat elfutils is distributed in the hope that it will be useful, but
11   WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   General Public License for more details.
14
15   You should have received a copy of the GNU General Public License along
16   with Red Hat elfutils; if not, write to the Free Software Foundation,
17   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18
19   In addition, as a special exception, Red Hat, Inc. gives You the
20   additional right to link the code of Red Hat elfutils with code licensed
21   under any Open Source Initiative certified open source license
22   (http://www.opensource.org/licenses/index.php) which requires the
23   distribution of source code with any binary distribution and to
24   distribute linked combinations of the two.  Non-GPL Code permitted under
25   this exception must only link to the code of Red Hat elfutils through
26   those well defined interfaces identified in the file named EXCEPTION
27   found in the source code files (the "Approved Interfaces").  The files
28   of Non-GPL Code may instantiate templates or use macros or inline
29   functions from the Approved Interfaces without causing the resulting
30   work to be covered by the GNU General Public License.  Only Red Hat,
31   Inc. may make changes or additions to the list of Approved Interfaces.
32   Red Hat's grant of this exception is conditioned upon your not adding
33   any new exceptions.  If you wish to add a new Approved Interface or
34   exception, please contact Red Hat.  You must obey the GNU General Public
35   License in all respects for all of the Red Hat elfutils code and other
36   code used in conjunction with Red Hat elfutils except the Non-GPL Code
37   covered by this exception.  If you modify this file, you may extend this
38   exception to your version of the file, but you are not obligated to do
39   so.  If you do not wish to provide this exception without modification,
40   you must delete this exception statement from your version and license
41   this file solely under the GPL without exception.
42
43   Red Hat elfutils is an included package of the Open Invention Network.
44   An included package of the Open Invention Network is a package for which
45   Open Invention Network licensees cross-license their patents.  No patent
46   license is granted, either expressly or impliedly, by designation as an
47   included package.  Should you wish to participate in the Open Invention
48   Network licensing program, please visit www.openinventionnetwork.com
49   <http://www.openinventionnetwork.com>.  */
50
51#ifdef HAVE_CONFIG_H
52# include <config.h>
53#endif
54
55#include <assert.h>
56#include <endian.h>
57#include <stdbool.h>
58#include <stddef.h>
59#include <string.h>
60
61#include "gelf.h"
62#include "libelfP.h"
63#include "elf-knowledge.h"
64
65#ifndef LIBELFBITS
66# define LIBELFBITS 32
67#endif
68
69
70/* The SECTION_STRIP_P macro wants to call into libebl which we cannot
71   do and do not have to do here.  Provide a dummy replacement.  */
72#define ebl_debugscn_p(ebl, name) true
73
74
75#define process_block(crc, data) \
76  __libelf_crc32 (crc, data->d_buf, data->d_size)
77
78
79long int
80elfw2(LIBELFBITS,checksum) (elf)
81     Elf *elf;
82{
83  size_t shstrndx;
84  Elf_Scn *scn;
85  long int result = 0;
86  unsigned char *ident;
87  bool same_byte_order;
88
89  if (elf == NULL)
90    return -1l;
91
92  /* Find the section header string table.  */
93  if  (INTUSE(elf_getshdrstrndx) (elf, &shstrndx) < 0)
94    {
95      /* This can only happen if the ELF handle is not for real.  */
96      __libelf_seterrno (ELF_E_INVALID_HANDLE);
97      return -1l;
98    }
99
100  /* Determine whether the byte order of the file and that of the host
101     is the same.  */
102  ident = elf->state.ELFW(elf,LIBELFBITS).ehdr->e_ident;
103  same_byte_order = ((ident[EI_DATA] == ELFDATA2LSB
104		      && __BYTE_ORDER == __LITTLE_ENDIAN)
105		     || (ident[EI_DATA] == ELFDATA2MSB
106			 && __BYTE_ORDER == __BIG_ENDIAN));
107
108  /* If we don't have native byte order, we will likely need to
109     convert the data with xlate functions.  We do it upfront instead
110     of relocking mid-iteration. */
111  if (!likely (same_byte_order))
112    rwlock_wrlock (elf->lock);
113  else
114    rwlock_rdlock (elf->lock);
115
116  /* Iterate over all sections to find those which are not strippable.  */
117  scn = NULL;
118  while ((scn = INTUSE(elf_nextscn) (elf, scn)) != NULL)
119    {
120      GElf_Shdr shdr_mem;
121      GElf_Shdr *shdr;
122      Elf_Data *data;
123
124      /* Get the section header.  */
125      shdr = INTUSE(gelf_getshdr) (scn, &shdr_mem);
126      if (shdr == NULL)
127	{
128	  __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
129	  result = -1l;
130	  goto out;
131	}
132
133      if (SECTION_STRIP_P (shdr,
134			   INTUSE(elf_strptr) (elf, shstrndx, shdr->sh_name),
135			   true))
136	/* The section can be stripped.  Don't use it.  */
137	continue;
138
139      /* Do not look at NOBITS sections.  */
140      if (shdr->sh_type == SHT_NOBITS)
141	continue;
142
143      /* To compute the checksum we need to get to the data.  For
144	 repeatable results we must use the external format.  The data
145	 we get with 'elf'getdata' might be changed for endianess
146	 reasons.  Therefore we use 'elf_rawdata' if possible.  But
147	 this function can fail if the data was constructed by the
148	 program.  In this case we have to use 'elf_getdata' and
149	 eventually convert the data to the external format.  */
150      data = INTUSE(elf_rawdata) (scn, NULL);
151      if (data != NULL)
152	{
153	  /* The raw data is available.  */
154	  result = process_block (result, data);
155
156	  /* Maybe the user added more data.  These blocks cannot be
157	     read using 'elf_rawdata'.  Simply proceed with looking
158	     for more data block with 'elf_getdata'.  */
159	}
160
161      /* Iterate through the list of data blocks.  */
162      while ((data = INTUSE(elf_getdata) (scn, data)) != NULL)
163	/* If the file byte order is the same as the host byte order
164	   process the buffer directly.  If the data is just a stream
165	   of bytes which the library will not convert we can use it
166	   as well.  */
167	if (likely (same_byte_order) || data->d_type == ELF_T_BYTE)
168	  result = process_block (result, data);
169	else
170	  {
171	    /* Convert the data to file byte order.  */
172	    if (INTUSE(elfw2(LIBELFBITS,xlatetof)) (data, data, ident[EI_DATA])
173		== NULL)
174	      {
175		result = -1l;
176		goto out;
177	      }
178
179	    result = process_block (result, data);
180
181	    /* And convert it back.  */
182	    if (INTUSE(elfw2(LIBELFBITS,xlatetom)) (data, data, ident[EI_DATA])
183		== NULL)
184	      {
185		result = -1l;
186		goto out;
187	      }
188	  }
189    }
190
191 out:
192  rwlock_unlock (elf->lock);
193  return result;
194}
195INTDEF(elfw2(LIBELFBITS,checksum))
196