mirror of
https://github.com/openharmony/third_party_elfutils.git
synced 2026-07-19 19:43:34 -04:00
Mark Wielaard
5199e15870
GNU Property notes are different from normal notes because they use variable alignment/padding of their fields. They are 8 byte aligned, but use 4 byte fields. The name is aligned at 4 bytes and padded so that, the desc is aligned at 8 bytes. The whole note is padded to 8 bytes again. For normal notes all fields are both 4 bytes wide and 4 bytes aligned. To recognize these new kind of ELF Notes a new Elf_Type is introduced, ELF_T_NHDR8. This type is used in the xlate functions to determine how to align and pad the various fields. Since the fields themselves can now have different alignments we will have to keep track of the current alignement and use either NOTE_ALIGN4 or NOTE_ALIGN8 to determine the padding. To set the correct Elf_Type on the Elf_Data we use either the section sh_addralign or the segment p_align values. Assuming 8 means the section or segment contains the new style notes, otherwise normal notes. When we cannot determine the "alignment" directly, like when parsing special kernel sys files, we check the name "GNU" and type "GNU_PROPERTY_TYPE_0" fields. ebl_object_note now parses the new NT_GNU_PROPERTY_TYPE_0 and can extract the GNU_PROPERTY_STACK_SIZE, GNU_PROPERTY_NO_COPY_ON_PROTECTED and GNU_PROPERTY_X86_FEATURE_1_AND types GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK. Tests are added for extracting the note from sections or segments as set by gcc -fcf-protection. Signed-off-by: Mark Wielaard <mark@klomp.org>
116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
/* Get note information at the supplied offset.
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Copyright (C) 2007, 2014, 2015, 2018 Red Hat, Inc.
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This file is part of elfutils.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <assert.h>
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#include <gelf.h>
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#include <string.h>
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#include "libelfP.h"
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size_t
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gelf_getnote (Elf_Data *data, size_t offset, GElf_Nhdr *result,
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size_t *name_offset, size_t *desc_offset)
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{
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if (data == NULL)
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return 0;
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if (unlikely (data->d_type != ELF_T_NHDR && data->d_type != ELF_T_NHDR8))
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{
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__libelf_seterrno (ELF_E_INVALID_HANDLE);
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return 0;
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}
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/* It's easy to handle this type. It has the same size for 32 and
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64 bit objects. */
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assert (sizeof (GElf_Nhdr) == sizeof (Elf32_Nhdr));
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assert (sizeof (GElf_Nhdr) == sizeof (Elf64_Nhdr));
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rwlock_rdlock (((Elf_Data_Scn *) data)->s->elf->lock);
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/* The data is already in the correct form. Just make sure the
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offset is OK. */
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if (unlikely (offset > data->d_size
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|| data->d_size - offset < sizeof (GElf_Nhdr)))
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{
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__libelf_seterrno (ELF_E_OFFSET_RANGE);
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offset = 0;
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}
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else
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{
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const GElf_Nhdr *n = data->d_buf + offset;
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offset += sizeof *n;
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if (offset > data->d_size)
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offset = 0;
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else
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{
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/* This is slightly tricky, offset is guaranteed to be 4
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byte aligned, which is what we need for the name_offset.
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And normally desc_offset is also 4 byte aligned, but not
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for GNU Property notes, then it should be 8. So align
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the offset, after adding the namesz, and include padding
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in descsz to get to the end. */
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*name_offset = offset;
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offset += n->n_namesz;
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if (offset > data->d_size)
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offset = 0;
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else
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{
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/* Include padding. Check below for overflow. */
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GElf_Word descsz = (data->d_type == ELF_T_NHDR8
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? NOTE_ALIGN8 (n->n_descsz)
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: NOTE_ALIGN4 (n->n_descsz));
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if (data->d_type == ELF_T_NHDR8)
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offset = NOTE_ALIGN8 (offset);
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else
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offset = NOTE_ALIGN4 (offset);
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if (unlikely (offset > data->d_size
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|| data->d_size - offset < descsz
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|| (descsz == 0 && n->n_descsz != 0)))
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offset = 0;
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else
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{
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*desc_offset = offset;
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offset += descsz;
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*result = *n;
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}
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}
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}
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}
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rwlock_unlock (((Elf_Data_Scn *) data)->s->elf->lock);
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return offset;
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}
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