Line data    Source code

       1             : /* Get note information at the supplied offset.
       2             :    Copyright (C) 2007, 2014, 2015, 2018 Red Hat, Inc.
       3             :    This file is part of elfutils.
       4             : 
       5             :    This file is free software; you can redistribute it and/or modify
       6             :    it under the terms of either
       7             : 
       8             :      * the GNU Lesser General Public License as published by the Free
       9             :        Software Foundation; either version 3 of the License, or (at
      10             :        your option) any later version
      11             : 
      12             :    or
      13             : 
      14             :      * the GNU General Public License as published by the Free
      15             :        Software Foundation; either version 2 of the License, or (at
      16             :        your option) any later version
      17             : 
      18             :    or both in parallel, as here.
      19             : 
      20             :    elfutils is distributed in the hope that it will be useful, but
      21             :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23             :    General Public License for more details.
      24             : 
      25             :    You should have received copies of the GNU General Public License and
      26             :    the GNU Lesser General Public License along with this program.  If
      27             :    not, see <http://www.gnu.org/licenses/>.  */
      28             : 
      29             : #ifdef HAVE_CONFIG_H
      30             : # include <config.h>
      31             : #endif
      32             : 
      33             : #include <assert.h>
      34             : #include <gelf.h>
      35             : #include <string.h>
      36             : 
      37             : #include "libelfP.h"
      38             : 
      39             : size_t
      40        2063 : gelf_getnote (Elf_Data *data, size_t offset, GElf_Nhdr *result,
      41             :               size_t *name_offset, size_t *desc_offset)
      42             : {
      43        2063 :   if (data == NULL)
      44             :     return 0;
      45             : 
      46        2063 :   if (unlikely (data->d_type != ELF_T_NHDR && data->d_type != ELF_T_NHDR8))
      47             :     {
      48           0 :       __libelf_seterrno (ELF_E_INVALID_HANDLE);
      49           0 :       return 0;
      50             :     }
      51             : 
      52             :   /* It's easy to handle this type.  It has the same size for 32 and
      53             :      64 bit objects.  */
      54             :   assert (sizeof (GElf_Nhdr) == sizeof (Elf32_Nhdr));
      55             :   assert (sizeof (GElf_Nhdr) == sizeof (Elf64_Nhdr));
      56             : 
      57             :   rwlock_rdlock (((Elf_Data_Scn *) data)->s->elf->lock);
      58             : 
      59             :   /* The data is already in the correct form.  Just make sure the
      60             :      offset is OK.  */
      61        2063 :   if (unlikely (offset > data->d_size
      62             :                 || data->d_size - offset < sizeof (GElf_Nhdr)))
      63             :     {
      64         145 :       __libelf_seterrno (ELF_E_OFFSET_RANGE);
      65         145 :       offset = 0;
      66             :     }
      67             :   else
      68             :     {
      69        1918 :       const GElf_Nhdr *n = data->d_buf + offset;
      70        1918 :       offset += sizeof *n;
      71             : 
      72        1918 :       if (offset > data->d_size)
      73             :         offset = 0;
      74             :       else
      75             :         {
      76             :           /* This is slightly tricky, offset is guaranteed to be 4
      77             :              byte aligned, which is what we need for the name_offset.
      78             :              And normally desc_offset is also 4 byte aligned, but not
      79             :              for GNU Property notes, then it should be 8.  So align
      80             :              the offset, after adding the namesz, and include padding
      81             :              in descsz to get to the end.  */
      82        1918 :           *name_offset = offset;
      83        1918 :           offset += n->n_namesz;
      84        1918 :           if (offset > data->d_size)
      85             :             offset = 0;
      86             :           else
      87             :             {
      88             :               /* Include padding.  Check below for overflow.  */
      89        1918 :               GElf_Word descsz = (data->d_type == ELF_T_NHDR8
      90           6 :                                   ? NOTE_ALIGN8 (n->n_descsz)
      91        1924 :                                   : NOTE_ALIGN4 (n->n_descsz));
      92             : 
      93        1918 :               if (data->d_type == ELF_T_NHDR8)
      94           6 :                 offset = NOTE_ALIGN8 (offset);
      95             :               else
      96        1912 :                 offset = NOTE_ALIGN4 (offset);
      97             : 
      98        1918 :               if (unlikely (offset > data->d_size
      99             :                             || data->d_size - offset < descsz
     100             :                             || (descsz == 0 && n->n_descsz != 0)))
     101             :                 offset = 0;
     102             :               else
     103             :                 {
     104        1918 :                   *desc_offset = offset;
     105        1918 :                   offset += descsz;
     106        1918 :                   *result = *n;
     107             :                 }
     108             :             }
     109             :         }
     110             :     }
     111             : 
     112             :   rwlock_unlock (((Elf_Data_Scn *) data)->s->elf->lock);
     113             : 
     114        2063 :   return offset;
     115             : }