mirror of
https://github.com/mozilla/gecko-dev.git
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b710b79390
Bug #119697
1221 lines
30 KiB
C
1221 lines
30 KiB
C
/* elf_gc_dynst
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*
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* This is a program that removes unreferenced strings from the .dynstr
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* section in ELF shared objects. It also shrinks the .dynstr section and
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* relocates all symbols after it.
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*
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* This program was written and copyrighted by:
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* Alexander Larsson <alla@lysator.liu.se>
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*
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*
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS"
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* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
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* License for the specific language governing rights and limitations
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* under the License.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#include <elf.h>
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#include <glib.h>
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#include <string.h>
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Elf32_Ehdr *elf_header = NULL;
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#define FILE_OFFSET(offset) ((unsigned char *)(elf_header) + (offset))
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struct dynamic_symbol {
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Elf32_Word old_index;
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Elf32_Word new_index;
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char *string;
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};
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GHashTable *used_dynamic_symbols = NULL;
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/* Data is dynamic_symbols, hashes on old_index */
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Elf32_Word hole_index;
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Elf32_Word hole_end;
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Elf32_Word hole_len;
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Elf32_Addr hole_addr_start;
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Elf32_Addr hole_addr_remap_start;
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Elf32_Addr hole_addr_remap_end;
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int need_byteswap;
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unsigned char machine_type;
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Elf32_Word
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read_word(Elf32_Word w)
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{
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if (need_byteswap)
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w = GUINT32_SWAP_LE_BE(w);
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return w;
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}
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Elf32_Sword
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read_sword(Elf32_Sword w)
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{
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if (need_byteswap)
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w = (Elf32_Sword)GUINT32_SWAP_LE_BE((guint32)w);
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return w;
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}
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void
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write_word(Elf32_Word *ptr, Elf32_Word w)
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{
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if (need_byteswap)
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w = GUINT32_SWAP_LE_BE(w);
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*ptr = w;
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}
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Elf32_Half
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read_half(Elf32_Half h)
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{
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if (need_byteswap)
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h = GUINT16_SWAP_LE_BE(h);
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return h;
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}
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void
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write_half(Elf32_Half *ptr, Elf32_Half h)
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{
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if (need_byteswap)
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h = GUINT16_SWAP_LE_BE(h);
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*ptr = h;
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}
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void
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setup_byteswapping(unsigned char ei_data)
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{
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need_byteswap = 0;
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#if G_BYTE_ORDER == G_BIG_ENDIAN
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if (ei_data == ELFDATA2LSB)
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need_byteswap = 1;
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#endif
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#if G_BYTE_ORDER == G_LITTLE_ENDIAN
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if (ei_data == ELFDATA2MSB)
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need_byteswap = 1;
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#endif
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}
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Elf32_Shdr *
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elf_find_section_num(int section_index)
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{
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Elf32_Shdr *section;
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Elf32_Word sectionsize;
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section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
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sectionsize = read_half(elf_header->e_shentsize);
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section = (Elf32_Shdr *)((char *)section + sectionsize*section_index);
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return section;
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}
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Elf32_Shdr *
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elf_find_section_named(char *name)
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{
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Elf32_Shdr *section;
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Elf32_Shdr *strtab_section;
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Elf32_Word sectionsize;
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int numsections;
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char *strtab;
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int i = 0;
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section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
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strtab_section = elf_find_section_num(read_half(elf_header->e_shstrndx));
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strtab = (char *)FILE_OFFSET(read_word(strtab_section->sh_offset));
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sectionsize = read_half(elf_header->e_shentsize);
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numsections = read_half(elf_header->e_shnum);
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for (i=0;i<numsections;i++) {
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if (strcmp(&strtab[read_word(section->sh_name)], name) == 0) {
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return section;
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}
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section = (Elf32_Shdr *)((char *)section + sectionsize);
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}
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return NULL;
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}
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Elf32_Shdr *
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elf_find_section(Elf32_Word sh_type)
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{
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Elf32_Shdr *section;
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Elf32_Word sectionsize;
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int numsections;
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int i = 0;
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section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
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sectionsize = read_half(elf_header->e_shentsize);
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numsections = read_half(elf_header->e_shnum);
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for (i=0;i<numsections;i++) {
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if (read_word(section->sh_type) == sh_type) {
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return section;
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}
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section = (Elf32_Shdr *)((char *)section + sectionsize);
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}
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return NULL;
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}
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Elf32_Shdr *
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elf_find_next_higher_section(Elf32_Word offset)
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{
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Elf32_Shdr *section;
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Elf32_Shdr *higher;
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Elf32_Word sectionsize;
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int numsections;
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int i = 0;
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section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
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sectionsize = read_half(elf_header->e_shentsize);
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numsections = read_half(elf_header->e_shnum);
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higher = NULL;
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for (i=0;i<numsections;i++) {
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if (read_word(section->sh_offset) >= offset) {
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if (higher == NULL) {
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higher = section;
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} else if (read_word(section->sh_offset) < read_word(higher->sh_offset)) {
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higher = section;
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}
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}
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section = (Elf32_Shdr *)((char *)section + sectionsize);
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}
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return higher;
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}
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Elf32_Word
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vma_to_offset(Elf32_Addr addr)
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{
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Elf32_Shdr *section;
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Elf32_Shdr *higher;
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Elf32_Word sectionsize;
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int numsections;
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int i = 0;
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section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
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sectionsize = read_half(elf_header->e_shentsize);
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numsections = read_half(elf_header->e_shnum);
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higher = NULL;
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for (i=0;i<numsections;i++) {
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if ( (addr >= read_word(section->sh_addr)) &&
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(addr < read_word(section->sh_addr) + read_word(section->sh_size)) ) {
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return read_word(section->sh_offset) + (addr - read_word(section->sh_addr));
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}
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section = (Elf32_Shdr *)((char *)section + sectionsize);
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}
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fprintf(stderr, "Warning, unable to convert address %d (0x%x) to file offset\n",
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addr, addr);
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return 0;
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}
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void
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find_segment_addr_min_max(Elf32_Word file_offset,
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Elf32_Addr *start, Elf32_Addr *end)
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{
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Elf32_Phdr *segment;
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Elf32_Word segmentsize;
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int numsegments;
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int i = 0;
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segment = (Elf32_Phdr *)FILE_OFFSET(read_word(elf_header->e_phoff));
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segmentsize = read_half(elf_header->e_phentsize);
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numsegments = read_half(elf_header->e_phnum);
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for (i=0;i<numsegments;i++) {
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if ((file_offset >= read_word(segment->p_offset)) &&
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(file_offset < read_word(segment->p_offset) + read_word(segment->p_filesz))) {
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*start = read_word(segment->p_vaddr);
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*end = read_word(segment->p_vaddr) + read_word(segment->p_memsz);
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return;
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}
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segment = (Elf32_Phdr *)((char *)segment + segmentsize);
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}
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fprintf(stderr, "Error: Couldn't find segment in find_segment_addr_min_max()\n");
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}
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void *
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dynamic_find_tag(Elf32_Shdr *dynamic, Elf32_Sword d_tag)
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{
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int i;
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Elf32_Dyn *element;
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element = (Elf32_Dyn *)FILE_OFFSET(read_word(dynamic->sh_offset));
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for (i=0; read_sword(element[i].d_tag) != DT_NULL; i++) {
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if (read_sword(element[i].d_tag) == d_tag) {
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return FILE_OFFSET(read_word(element[i].d_un.d_ptr));
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}
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}
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return NULL;
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}
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Elf32_Word
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fixup_offset(Elf32_Word offset)
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{
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if (offset >= hole_index) {
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return offset - hole_len;
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}
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return offset;
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}
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Elf32_Word
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fixup_size(Elf32_Word offset, Elf32_Word size)
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{
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/* Note: Doesn't handle the cases where the hole and the size intersect
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partially. */
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if ( (hole_index >= offset) &&
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(hole_index < offset + size)){
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return size - hole_len;
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}
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return size;
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}
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Elf32_Addr
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fixup_addr(Elf32_Addr addr)
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{
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if (addr == 0)
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return 0;
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/*
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if ( (addr < hole_addr_remap_start) ||
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(addr >= hole_addr_remap_end))
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return addr;
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*/
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if (addr >= hole_addr_start) {
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return addr - hole_len;
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}
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return addr;
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}
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Elf32_Word
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fixup_addr_size(Elf32_Addr addr, Elf32_Word size)
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{
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/* Note: Doesn't handle the cases where the hole and the size intersect
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partially. */
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/*
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if ( (addr < hole_addr_remap_start) ||
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(addr >= hole_addr_remap_end))
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return size;
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*/
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if ( (hole_addr_start >= addr) &&
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(hole_addr_start < addr + size)){
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return size - hole_len;
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}
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return size;
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}
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void
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possibly_add_string(int name_idx, const char *name)
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{
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struct dynamic_symbol *dynamic_symbol;
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if (name_idx != 0) {
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dynamic_symbol = g_hash_table_lookup(used_dynamic_symbols, (gpointer) name_idx);
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if (dynamic_symbol == NULL) {
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dynamic_symbol = g_new(struct dynamic_symbol, 1);
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dynamic_symbol->old_index = name_idx;
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dynamic_symbol->new_index = 0;
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dynamic_symbol->string = g_strdup(name);
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g_hash_table_insert(used_dynamic_symbols, (gpointer)name_idx, dynamic_symbol);
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/*printf("added dynamic string: %s (%d)\n", dynamic_symbol->string, name_idx);*/
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}
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}
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}
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Elf32_Word
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fixup_string(Elf32_Word old_idx)
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{
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struct dynamic_symbol *dynamic_symbol;
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if (old_idx == 0)
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return 0;
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dynamic_symbol = g_hash_table_lookup(used_dynamic_symbols, (gpointer) old_idx);
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if (dynamic_symbol == NULL) {
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fprintf(stderr, "AAAAAAAAAAAARGH!? Unknown string found in fixup (index: %d)!\n", old_idx);
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return 0;
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}
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return dynamic_symbol->new_index;
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}
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void
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add_strings_from_dynsym(Elf32_Shdr *dynsym, char *strtab)
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{
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Elf32_Sym *symbol;
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Elf32_Sym *symbol_end;
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Elf32_Word entry_size;
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symbol = (Elf32_Sym *)FILE_OFFSET(read_word(dynsym->sh_offset));
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symbol_end = (Elf32_Sym *)FILE_OFFSET(read_word(dynsym->sh_offset) + read_word(dynsym->sh_size));
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entry_size = read_word(dynsym->sh_entsize);
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while (symbol < symbol_end) {
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int name_idx;
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struct dynamic_symbol *dynamic_symbol;
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name_idx = read_word(symbol->st_name);
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possibly_add_string(name_idx, &strtab[name_idx]);
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symbol = (Elf32_Sym *)((char *)symbol + entry_size);
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}
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}
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void
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fixup_strings_in_dynsym(Elf32_Shdr *dynsym)
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{
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Elf32_Sym *symbol;
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Elf32_Sym *symbol_end;
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Elf32_Word entry_size;
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symbol = (Elf32_Sym *)FILE_OFFSET(read_word(dynsym->sh_offset));
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symbol_end = (Elf32_Sym *)FILE_OFFSET(read_word(dynsym->sh_offset) + read_word(dynsym->sh_size));
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entry_size = read_word(dynsym->sh_entsize);
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while (symbol < symbol_end) {
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struct dynamic_symbol *dynamic_symbol;
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write_word(&symbol->st_name,
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fixup_string(read_word(symbol->st_name)));
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symbol = (Elf32_Sym *)((char *)symbol + entry_size);
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}
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}
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void
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add_strings_from_dynamic(Elf32_Shdr *dynamic, char *strtab)
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{
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int i;
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int name_idx;
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Elf32_Dyn *element;
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Elf32_Word entry_size;
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entry_size = read_word(dynamic->sh_entsize);
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element = (Elf32_Dyn *)FILE_OFFSET(read_word(dynamic->sh_offset));
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while (read_sword(element->d_tag) != DT_NULL) {
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switch(read_sword(element->d_tag)) {
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case DT_NEEDED:
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case DT_SONAME:
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case DT_RPATH:
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name_idx = read_word(element->d_un.d_val);
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/*if (name_idx) printf("d_tag: %d\n", element->d_tag);*/
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possibly_add_string(name_idx, &strtab[name_idx]);
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break;
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default:
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;
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/*printf("unhandled d_tag: %d (0x%x)\n", element->d_tag, element->d_tag);*/
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}
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element = (Elf32_Dyn *)((char *)element + entry_size);
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}
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}
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void
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fixup_strings_in_dynamic(Elf32_Shdr *dynamic)
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{
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int i;
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int name_idx;
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Elf32_Dyn *element;
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Elf32_Word entry_size;
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entry_size = read_word(dynamic->sh_entsize);
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element = (Elf32_Dyn *)FILE_OFFSET(read_word(dynamic->sh_offset));
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while (read_sword(element->d_tag) != DT_NULL) {
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switch(read_sword(element->d_tag)) {
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case DT_NEEDED:
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case DT_SONAME:
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case DT_RPATH:
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write_word(&element->d_un.d_val,
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fixup_string(read_word(element->d_un.d_val)));
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break;
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default:
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;
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/*printf("unhandled d_tag: %d (0x%x)\n", element->d_tag, element->d_tag);*/
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}
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element = (Elf32_Dyn *)((char *)element + entry_size);
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}
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}
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void
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add_strings_from_ver_d(Elf32_Shdr *ver_d, char *strtab)
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{
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Elf32_Verdaux *veraux;
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Elf32_Verdef *verdef;
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int num_aux;
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int name_idx;
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int i;
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int cont;
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verdef = (Elf32_Verdef *)FILE_OFFSET(read_word(ver_d->sh_offset));
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do {
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num_aux = read_half(verdef->vd_cnt);
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veraux = (Elf32_Verdaux *)((char *)verdef + read_word(verdef->vd_aux));
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for (i=0; i<num_aux; i++) {
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name_idx = read_word(veraux->vda_name);
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possibly_add_string(name_idx, &strtab[name_idx]);
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veraux = (Elf32_Verdaux *)((char *)veraux + read_word(veraux->vda_next));
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}
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cont = read_word(verdef->vd_next) != 0;
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verdef = (Elf32_Verdef *)((char *)verdef + read_word(verdef->vd_next));
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} while (cont);
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}
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void
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fixup_strings_in_ver_d(Elf32_Shdr *ver_d)
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{
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Elf32_Verdaux *veraux;
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Elf32_Verdef *verdef;
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int num_aux;
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int name_idx;
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int i;
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int cont;
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verdef = (Elf32_Verdef *)FILE_OFFSET(read_word(ver_d->sh_offset));
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do {
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num_aux = read_half(verdef->vd_cnt);
|
|
veraux = (Elf32_Verdaux *)((char *)verdef + read_word(verdef->vd_aux));
|
|
for (i=0; i<num_aux; i++) {
|
|
write_word(&veraux->vda_name,
|
|
fixup_string(read_word(veraux->vda_name)));
|
|
veraux = (Elf32_Verdaux *)((char *)veraux + read_word(veraux->vda_next));
|
|
}
|
|
|
|
cont = read_word(verdef->vd_next) != 0;
|
|
verdef = (Elf32_Verdef *)((char *)verdef + read_word(verdef->vd_next));
|
|
} while (cont);
|
|
|
|
}
|
|
|
|
void
|
|
add_strings_from_ver_r(Elf32_Shdr *ver_r, char *strtab)
|
|
{
|
|
Elf32_Vernaux *veraux;
|
|
Elf32_Verneed *verneed;
|
|
int num_aux;
|
|
int name_idx;
|
|
int i;
|
|
int cont;
|
|
|
|
verneed = (Elf32_Verneed *)FILE_OFFSET(read_word(ver_r->sh_offset));
|
|
|
|
do {
|
|
name_idx = read_word(verneed->vn_file);
|
|
possibly_add_string(name_idx, &strtab[name_idx]);
|
|
num_aux = read_half(verneed->vn_cnt);
|
|
veraux = (Elf32_Vernaux *)((char *)verneed + read_word(verneed->vn_aux));
|
|
for (i=0; i<num_aux; i++) {
|
|
name_idx = read_word(veraux->vna_name);
|
|
possibly_add_string(name_idx, &strtab[name_idx]);
|
|
veraux = (Elf32_Vernaux *)((char *)veraux + read_word(veraux->vna_next));
|
|
}
|
|
|
|
cont = read_word(verneed->vn_next) != 0;
|
|
verneed = (Elf32_Verneed *)((char *)verneed + read_word(verneed->vn_next));
|
|
} while (cont);
|
|
}
|
|
|
|
void
|
|
fixup_strings_in_ver_r(Elf32_Shdr *ver_r)
|
|
{
|
|
Elf32_Vernaux *veraux;
|
|
Elf32_Verneed *verneed;
|
|
int num_aux;
|
|
int name_idx;
|
|
int i;
|
|
int cont;
|
|
|
|
verneed = (Elf32_Verneed *)FILE_OFFSET(read_word(ver_r->sh_offset));
|
|
|
|
do {
|
|
write_word(&verneed->vn_file,
|
|
fixup_string(read_word(verneed->vn_file)));
|
|
num_aux = read_half(verneed->vn_cnt);
|
|
veraux = (Elf32_Vernaux *)((char *)verneed + read_word(verneed->vn_aux));
|
|
for (i=0; i<num_aux; i++) {
|
|
write_word(&veraux->vna_name,
|
|
fixup_string(read_word(veraux->vna_name)));
|
|
veraux = (Elf32_Vernaux *)((char *)veraux + read_word(veraux->vna_next));
|
|
}
|
|
|
|
cont = read_word(verneed->vn_next) != 0;
|
|
verneed = (Elf32_Verneed *)((char *)verneed + read_word(verneed->vn_next));
|
|
} while (cont);
|
|
}
|
|
|
|
gboolean sum_size(gpointer key,
|
|
struct dynamic_symbol *sym,
|
|
int *size)
|
|
{
|
|
*size += strlen(sym->string) + 1;
|
|
return 1;
|
|
}
|
|
|
|
struct index_n_dynstr {
|
|
int index;
|
|
unsigned char *dynstr;
|
|
};
|
|
|
|
gboolean output_string(gpointer key,
|
|
struct dynamic_symbol *sym,
|
|
struct index_n_dynstr *x)
|
|
{
|
|
sym->new_index = x->index;
|
|
memcpy(x->dynstr + x->index, sym->string, strlen(sym->string) + 1);
|
|
x->index += strlen(sym->string) + 1;
|
|
return 1;
|
|
}
|
|
|
|
|
|
unsigned char *
|
|
generate_new_dynstr(Elf32_Word *size_out)
|
|
{
|
|
int size;
|
|
unsigned char *new_dynstr;
|
|
struct index_n_dynstr x;
|
|
|
|
size = 1; /* first a zero */
|
|
g_hash_table_foreach (used_dynamic_symbols,
|
|
(GHFunc)sum_size,
|
|
&size);
|
|
|
|
|
|
new_dynstr = g_malloc(size);
|
|
|
|
new_dynstr[0] = 0;
|
|
x.index = 1;
|
|
x.dynstr = new_dynstr;
|
|
g_hash_table_foreach (used_dynamic_symbols,
|
|
(GHFunc)output_string,
|
|
&x);
|
|
|
|
*size_out = size;
|
|
return new_dynstr;
|
|
}
|
|
|
|
void
|
|
remap_sections(void)
|
|
{
|
|
Elf32_Shdr *section;
|
|
Elf32_Word sectionsize;
|
|
int numsections;
|
|
int i = 0;
|
|
|
|
section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
|
|
sectionsize = read_half(elf_header->e_shentsize);
|
|
numsections = read_half(elf_header->e_shnum);
|
|
|
|
for (i=0;i<numsections;i++) {
|
|
write_word(§ion->sh_size,
|
|
fixup_size(read_word(section->sh_offset),
|
|
read_word(section->sh_size)));
|
|
write_word(§ion->sh_offset,
|
|
fixup_offset(read_word(section->sh_offset)));
|
|
write_word(§ion->sh_addr,
|
|
fixup_addr(read_word(section->sh_addr)));
|
|
|
|
section = (Elf32_Shdr *)((char *)section + sectionsize);
|
|
}
|
|
}
|
|
|
|
|
|
void
|
|
remap_segments(void)
|
|
{
|
|
Elf32_Phdr *segment;
|
|
Elf32_Word segmentsize;
|
|
Elf32_Word p_align;
|
|
int numsegments;
|
|
int i = 0;
|
|
|
|
segment = (Elf32_Phdr *)FILE_OFFSET(read_word(elf_header->e_phoff));
|
|
segmentsize = read_half(elf_header->e_phentsize);
|
|
numsegments = read_half(elf_header->e_phnum);
|
|
|
|
for (i=0;i<numsegments;i++) {
|
|
write_word(&segment->p_filesz,
|
|
fixup_size(read_word(segment->p_offset),
|
|
read_word(segment->p_filesz)));
|
|
write_word(&segment->p_offset,
|
|
fixup_offset(read_word(segment->p_offset)));
|
|
|
|
write_word(&segment->p_memsz,
|
|
fixup_addr_size(read_word(segment->p_vaddr),
|
|
read_word(segment->p_memsz)));
|
|
write_word(&segment->p_vaddr,
|
|
fixup_addr(read_word(segment->p_vaddr)));
|
|
write_word(&segment->p_paddr,
|
|
read_word(segment->p_vaddr));
|
|
|
|
/* Consistancy checking: */
|
|
p_align = read_word(segment->p_align);
|
|
if (p_align > 1) {
|
|
if ((read_word(segment->p_vaddr) - read_word(segment->p_offset))%p_align != 0) {
|
|
fprintf(stderr, "Warning, creating non-aligned segment addr: %x offset: %x allign: %x\n",
|
|
read_word(segment->p_vaddr), read_word(segment->p_offset), p_align);
|
|
}
|
|
}
|
|
|
|
segment = (Elf32_Phdr *)((char *)segment + segmentsize);
|
|
}
|
|
}
|
|
|
|
void
|
|
remap_elf_header(void)
|
|
{
|
|
write_word(&elf_header->e_phoff,
|
|
fixup_offset(read_word(elf_header->e_phoff)));
|
|
write_word(&elf_header->e_shoff,
|
|
fixup_offset(read_word(elf_header->e_shoff)));
|
|
|
|
write_word(&elf_header->e_entry,
|
|
fixup_addr(read_word(elf_header->e_entry)));
|
|
}
|
|
|
|
void
|
|
remap_symtab(Elf32_Shdr *symtab)
|
|
{
|
|
Elf32_Sym *symbol;
|
|
Elf32_Sym *symbol_end;
|
|
Elf32_Word entry_size;
|
|
|
|
symbol = (Elf32_Sym *)FILE_OFFSET(read_word(symtab->sh_offset));
|
|
symbol_end = (Elf32_Sym *)FILE_OFFSET(read_word(symtab->sh_offset) +
|
|
read_word(symtab->sh_size));
|
|
entry_size = read_word(symtab->sh_entsize);
|
|
|
|
while (symbol < symbol_end) {
|
|
write_word(&symbol->st_value,
|
|
fixup_addr(read_word(symbol->st_value)));
|
|
symbol = (Elf32_Sym *)((char *)symbol + entry_size);
|
|
}
|
|
}
|
|
|
|
|
|
/* Ugly global variables: */
|
|
Elf32_Addr got_data_start = 0;
|
|
Elf32_Addr got_data_end = 0;
|
|
|
|
|
|
void
|
|
remap_rel_section(Elf32_Rel *rel, Elf32_Word size, Elf32_Word entry_size)
|
|
{
|
|
Elf32_Rel *rel_end;
|
|
Elf32_Word offset;
|
|
Elf32_Addr *addr;
|
|
Elf32_Word type;
|
|
|
|
rel_end = (Elf32_Rel *)((char *)rel + size);
|
|
|
|
while (rel < rel_end) {
|
|
type = ELF32_R_TYPE(read_word(rel->r_info));
|
|
switch (machine_type) {
|
|
case EM_386:
|
|
if ((type == R_386_RELATIVE) || (type == R_386_JMP_SLOT)) {
|
|
/* We need to relocate the data this is pointing to too. */
|
|
offset = vma_to_offset(read_word(rel->r_offset));
|
|
|
|
addr = (Elf32_Addr *)FILE_OFFSET(offset);
|
|
write_word(addr,
|
|
fixup_addr(read_word(*addr)));
|
|
}
|
|
write_word(&rel->r_offset,
|
|
fixup_addr(read_word(rel->r_offset)));
|
|
break;
|
|
case EM_PPC:
|
|
/* The PPC always uses RELA relocations */
|
|
break;
|
|
}
|
|
|
|
|
|
rel = (Elf32_Rel *)((char *)rel + entry_size);
|
|
}
|
|
}
|
|
|
|
void
|
|
remap_rela_section(Elf32_Rela *rela, Elf32_Word size, Elf32_Word entry_size)
|
|
{
|
|
Elf32_Rela *rela_end;
|
|
Elf32_Addr *addr;
|
|
Elf32_Word offset;
|
|
Elf32_Word type;
|
|
Elf32_Word bitmask;
|
|
|
|
rela_end = (Elf32_Rela *)((char *)rela + size);
|
|
|
|
while (rela < rela_end) {
|
|
type = ELF32_R_TYPE(read_word(rela->r_info));
|
|
switch (machine_type) {
|
|
case EM_386:
|
|
if ((type == R_386_RELATIVE) || (type == R_386_JMP_SLOT)) {
|
|
/* We need to relocate the data this is pointing to too. */
|
|
offset = vma_to_offset(read_word(rela->r_offset));
|
|
|
|
addr = (Elf32_Addr *)FILE_OFFSET(offset);
|
|
write_word(addr,
|
|
fixup_addr(read_word(*addr)));
|
|
}
|
|
write_word(&rela->r_offset,
|
|
fixup_addr(read_word(rela->r_offset)));
|
|
break;
|
|
case EM_PPC:
|
|
/* Some systems do not have PowerPC relocations defined */
|
|
#ifdef R_PPC_NONE
|
|
switch (type) {
|
|
case R_PPC_RELATIVE:
|
|
write_word((Elf32_Word *)&rela->r_addend,
|
|
fixup_addr(read_word(rela->r_addend)));
|
|
/* Fall through for 32bit offset fixup */
|
|
case R_PPC_ADDR32:
|
|
case R_PPC_GLOB_DAT:
|
|
case R_PPC_JMP_SLOT:
|
|
write_word(&rela->r_offset,
|
|
fixup_addr(read_word(rela->r_offset)));
|
|
break;
|
|
case R_PPC_NONE:
|
|
break;
|
|
default:
|
|
fprintf(stderr, "Warning, unhandled PPC relocation type %d\n", type);
|
|
}
|
|
#endif
|
|
break;
|
|
}
|
|
|
|
rela = (Elf32_Rela *)((char *)rela + entry_size);
|
|
}
|
|
}
|
|
|
|
void
|
|
remap_i386_got(void)
|
|
{
|
|
Elf32_Shdr *got_section;
|
|
Elf32_Addr *got;
|
|
Elf32_Addr *got_end;
|
|
Elf32_Word entry_size;
|
|
|
|
got_section = elf_find_section_named(".got");
|
|
if (got_section == NULL) {
|
|
fprintf(stderr, "Warning, no .got section\n");
|
|
return;
|
|
}
|
|
|
|
got_data_start = read_word(got_section->sh_offset);
|
|
got_data_end = got_data_start + read_word(got_section->sh_size);
|
|
|
|
got = (Elf32_Addr *)FILE_OFFSET(got_data_start);
|
|
got_end = (Elf32_Addr *)FILE_OFFSET(got_data_end);
|
|
entry_size = read_word(got_section->sh_entsize);
|
|
|
|
write_word(got,
|
|
fixup_addr(read_word(*got))); /* Pointer to .dynamic */
|
|
}
|
|
|
|
void
|
|
remap_ppc_got(void)
|
|
{
|
|
Elf32_Shdr *got_section;
|
|
Elf32_Addr *got;
|
|
Elf32_Addr *got_end;
|
|
Elf32_Word entry_size;
|
|
|
|
got_section = elf_find_section_named(".got");
|
|
if (got_section == NULL) {
|
|
fprintf(stderr, "Warning, no .got section\n");
|
|
return;
|
|
}
|
|
|
|
got_data_start = read_word(got_section->sh_offset);
|
|
got_data_end = got_data_start + read_word(got_section->sh_size);
|
|
|
|
got = (Elf32_Addr *)FILE_OFFSET(got_data_start);
|
|
got_end = (Elf32_Addr *)FILE_OFFSET(got_data_end);
|
|
entry_size = read_word(got_section->sh_entsize);
|
|
|
|
/* Skip reserved part.
|
|
* Note that this should really be found by finding the
|
|
* _GLOBAL_OFFSET_TABLE symbol, as it could (according to
|
|
* the spec) point to the middle of the got.
|
|
*/
|
|
got = (Elf32_Addr *)((char *)got + entry_size); /* Skip blrl instruction */
|
|
write_word(got,
|
|
fixup_addr(read_word(*got))); /* Pointer to .dynamic */
|
|
}
|
|
|
|
|
|
Elf32_Word
|
|
get_dynamic_val(Elf32_Shdr *dynamic, Elf32_Sword tag)
|
|
{
|
|
Elf32_Dyn *element;
|
|
Elf32_Word entry_size;
|
|
|
|
entry_size = read_word(dynamic->sh_entsize);
|
|
|
|
element = (Elf32_Dyn *)FILE_OFFSET(read_word(dynamic->sh_offset));
|
|
while (read_sword(element->d_tag) != DT_NULL) {
|
|
if (read_sword(element->d_tag) == tag) {
|
|
return read_word(element->d_un.d_val);
|
|
}
|
|
element = (Elf32_Dyn *)((char *)element + entry_size);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void
|
|
remap_dynamic(Elf32_Shdr *dynamic, Elf32_Word new_dynstr_size)
|
|
{
|
|
Elf32_Dyn *element;
|
|
Elf32_Word entry_size;
|
|
Elf32_Word rel_size;
|
|
Elf32_Word rel_entry_size;
|
|
Elf32_Rel *rel;
|
|
Elf32_Rela *rela;
|
|
int jmprel_overlaps;
|
|
Elf32_Word rel_start, rel_end, jmprel_start, jmprel_end;
|
|
|
|
entry_size = read_word(dynamic->sh_entsize);
|
|
|
|
/* Find out if REL/RELA and JMPREL overlaps: */
|
|
if (get_dynamic_val(dynamic, DT_PLTREL) == DT_REL) {
|
|
rel_start = get_dynamic_val(dynamic, DT_REL);
|
|
rel_end = rel_start + get_dynamic_val(dynamic, DT_RELSZ);
|
|
} else {
|
|
rel_start = get_dynamic_val(dynamic, DT_RELA);
|
|
rel_end = rel_start + get_dynamic_val(dynamic, DT_RELASZ);
|
|
}
|
|
jmprel_start = get_dynamic_val(dynamic, DT_JMPREL);
|
|
|
|
jmprel_overlaps = 0;
|
|
if ((jmprel_start >= rel_start) && (jmprel_start < rel_end))
|
|
jmprel_overlaps = 1;
|
|
|
|
element = (Elf32_Dyn *)FILE_OFFSET(read_word(dynamic->sh_offset));
|
|
while (read_sword(element->d_tag) != DT_NULL) {
|
|
switch(read_sword(element->d_tag)) {
|
|
case DT_STRSZ:
|
|
write_word(&element->d_un.d_val, new_dynstr_size);
|
|
break;
|
|
case DT_PLTGOT:
|
|
case DT_HASH:
|
|
case DT_STRTAB:
|
|
case DT_INIT:
|
|
case DT_FINI:
|
|
case DT_VERDEF:
|
|
case DT_VERNEED:
|
|
case DT_VERSYM:
|
|
write_word(&element->d_un.d_ptr,
|
|
fixup_addr(read_word(element->d_un.d_ptr)));
|
|
break;
|
|
case DT_JMPREL:
|
|
rel_size = get_dynamic_val(dynamic, DT_PLTRELSZ);
|
|
if (!jmprel_overlaps) {
|
|
if (get_dynamic_val(dynamic, DT_PLTREL) == DT_REL) {
|
|
rel_entry_size = get_dynamic_val(dynamic, DT_RELENT);
|
|
rel = (Elf32_Rel *)FILE_OFFSET(vma_to_offset(read_word(element->d_un.d_ptr)));
|
|
remap_rel_section(rel, rel_size, rel_entry_size);
|
|
} else {
|
|
rel_entry_size = get_dynamic_val(dynamic, DT_RELAENT);
|
|
rela = (Elf32_Rela *)FILE_OFFSET(vma_to_offset(read_word(element->d_un.d_ptr)));
|
|
remap_rela_section(rela, rel_size, rel_entry_size);
|
|
}
|
|
}
|
|
write_word(&element->d_un.d_ptr,
|
|
fixup_addr(read_word(element->d_un.d_ptr)));
|
|
break;
|
|
case DT_REL:
|
|
rel_size = get_dynamic_val(dynamic, DT_RELSZ);
|
|
rel_entry_size = get_dynamic_val(dynamic, DT_RELENT);
|
|
rel = (Elf32_Rel *)FILE_OFFSET(vma_to_offset(read_word(element->d_un.d_ptr)));
|
|
remap_rel_section(rel, rel_size, rel_entry_size);
|
|
|
|
write_word(&element->d_un.d_ptr,
|
|
fixup_addr(read_word(element->d_un.d_ptr)));
|
|
break;
|
|
case DT_RELA:
|
|
rel_size = get_dynamic_val(dynamic, DT_RELASZ);
|
|
rel_entry_size = get_dynamic_val(dynamic, DT_RELAENT);
|
|
rela = (Elf32_Rela *)FILE_OFFSET(vma_to_offset(read_word(element->d_un.d_ptr)));
|
|
remap_rela_section(rela, rel_size, rel_entry_size);
|
|
|
|
write_word(&element->d_un.d_ptr,
|
|
fixup_addr(read_word(element->d_un.d_ptr)));
|
|
break;
|
|
default:
|
|
/*printf("unhandled d_tag: %d (0x%x)\n", read_sword(element->d_tag), read_sword(element->d_tag));*/
|
|
break;
|
|
}
|
|
|
|
element = (Elf32_Dyn *)((char *)element + entry_size);
|
|
}
|
|
}
|
|
|
|
void
|
|
align_hole(Elf32_Word *start, Elf32_Word *end)
|
|
{
|
|
Elf32_Word len;
|
|
Elf32_Word align;
|
|
Elf32_Shdr *section;
|
|
Elf32_Word sectionsize;
|
|
int numsections;
|
|
int i = 0;
|
|
int unaligned;
|
|
|
|
len = *end - *start;
|
|
align = 0;
|
|
|
|
sectionsize = read_half(elf_header->e_shentsize);
|
|
numsections = read_half(elf_header->e_shnum);
|
|
do {
|
|
section = (Elf32_Shdr *)FILE_OFFSET(read_word(elf_header->e_shoff));
|
|
unaligned = 0;
|
|
|
|
for (i=0;i<numsections;i++) {
|
|
if ( (read_word(section->sh_addralign) > 1) &&
|
|
( (read_word(section->sh_offset) - len + align)%read_word(section->sh_addralign) != 0) ) {
|
|
unaligned = 1;
|
|
}
|
|
|
|
section = (Elf32_Shdr *)((char *)section + sectionsize);
|
|
}
|
|
|
|
if (unaligned) {
|
|
align++;
|
|
}
|
|
|
|
} while (unaligned);
|
|
|
|
*start += align;
|
|
}
|
|
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
int fd;
|
|
unsigned char *mapping;
|
|
Elf32_Word size;
|
|
struct stat statbuf;
|
|
Elf32_Shdr *dynamic;
|
|
Elf32_Shdr *dynsym;
|
|
Elf32_Shdr *symtab;
|
|
Elf32_Shdr *dynstr;
|
|
Elf32_Shdr *hash;
|
|
Elf32_Shdr *higher_section;
|
|
Elf32_Word dynstr_index;
|
|
Elf32_Shdr *ver_r;
|
|
Elf32_Shdr *ver_d;
|
|
char *dynstr_data;
|
|
unsigned char *new_dynstr;
|
|
Elf32_Word old_dynstr_size;
|
|
Elf32_Word new_dynstr_size;
|
|
|
|
if (argc != 2) {
|
|
fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
|
|
return 1;
|
|
}
|
|
|
|
fd = open(argv[1], O_RDWR);
|
|
if (fd == -1) {
|
|
fprintf(stderr, "Cannot open file %s\n", argv[1]);
|
|
return 1;
|
|
}
|
|
|
|
if (fstat(fd, &statbuf) == -1) {
|
|
fprintf(stderr, "Cannot stat file %s\n", argv[1]);
|
|
return 1;
|
|
}
|
|
|
|
size = statbuf.st_size;
|
|
|
|
mapping = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
|
|
|
|
if (mapping == (unsigned char *)-1) {
|
|
fprintf(stderr, "Cannot mmap file %s\n", argv[1]);
|
|
return 1;
|
|
}
|
|
|
|
used_dynamic_symbols = g_hash_table_new(g_direct_hash, g_direct_equal);
|
|
|
|
elf_header = (Elf32_Ehdr *)mapping;
|
|
|
|
if (strncmp((void *)elf_header, ELFMAG, SELFMAG)!=0) {
|
|
fprintf(stderr, "Not an ELF file\n");
|
|
return 1;
|
|
}
|
|
|
|
if (elf_header->e_ident[EI_VERSION] != EV_CURRENT) {
|
|
fprintf(stderr, "Wrong ELF file version\n");
|
|
return 1;
|
|
}
|
|
|
|
if (elf_header->e_ident[EI_CLASS] != ELFCLASS32) {
|
|
fprintf(stderr, "Only 32bit ELF files supported\n");
|
|
return 1;
|
|
}
|
|
|
|
setup_byteswapping(elf_header->e_ident[EI_DATA]);
|
|
|
|
machine_type = read_half(elf_header->e_machine);
|
|
if ( (machine_type != EM_386) &&
|
|
(machine_type != EM_PPC) ) {
|
|
fprintf(stderr, "Unsupported architecture. Supported are: x86, ppc\n");
|
|
return 1;
|
|
}
|
|
|
|
if (read_half(elf_header->e_type) != ET_DYN) {
|
|
fprintf(stderr, "Not an ELF shared object\n");
|
|
return 1;
|
|
}
|
|
|
|
dynamic = elf_find_section(SHT_DYNAMIC);
|
|
dynsym = elf_find_section(SHT_DYNSYM);
|
|
symtab = elf_find_section(SHT_SYMTAB);
|
|
dynstr_index = read_word(dynsym->sh_link);
|
|
dynstr = elf_find_section_num(dynstr_index);
|
|
dynstr_data = (char *)FILE_OFFSET(read_word(dynstr->sh_offset));
|
|
old_dynstr_size = read_word(dynstr->sh_size);
|
|
ver_d = elf_find_section(SHT_GNU_verdef);
|
|
ver_r = elf_find_section(SHT_GNU_verneed);
|
|
hash = elf_find_section(SHT_HASH);
|
|
|
|
/* Generate hash table with all used strings: */
|
|
|
|
add_strings_from_dynsym(dynsym, dynstr_data);
|
|
add_strings_from_dynamic(dynamic, dynstr_data);
|
|
if (ver_d && (read_word(ver_d->sh_link) == dynstr_index))
|
|
add_strings_from_ver_d(ver_d, dynstr_data);
|
|
if (ver_r && (read_word(ver_r->sh_link) == dynstr_index))
|
|
add_strings_from_ver_r(ver_r, dynstr_data);
|
|
|
|
/* Generate new dynstr section from the used strings hashtable: */
|
|
|
|
new_dynstr = generate_new_dynstr(&new_dynstr_size);
|
|
/*
|
|
printf("New dynstr size: %d\n", new_dynstr_size);
|
|
printf("Old dynstr size: %d\n", old_dynstr_size);
|
|
*/
|
|
|
|
if (new_dynstr_size >= old_dynstr_size) {
|
|
fprintf(stderr, "Couldn't GC any strings, exiting.\n");
|
|
return 0;
|
|
}
|
|
|
|
/* Fixup all references: */
|
|
fixup_strings_in_dynsym(dynsym);
|
|
fixup_strings_in_dynamic(dynamic);
|
|
if (ver_d && (read_word(ver_d->sh_link) == dynstr_index))
|
|
fixup_strings_in_ver_d(ver_d);
|
|
if (ver_r && (read_word(ver_r->sh_link) == dynstr_index))
|
|
fixup_strings_in_ver_r(ver_r);
|
|
|
|
/* Copy over the new dynstr: */
|
|
memcpy(dynstr_data, new_dynstr, new_dynstr_size);
|
|
memset(dynstr_data + new_dynstr_size, ' ', old_dynstr_size-new_dynstr_size);
|
|
|
|
/* Compact the dynstr section and the file: */
|
|
|
|
/* 1. Set up the data for the fixup_offset() function: */
|
|
hole_index = read_word(dynstr->sh_offset) + new_dynstr_size;
|
|
higher_section = elf_find_next_higher_section(hole_index);
|
|
hole_end = read_word(higher_section->sh_offset);
|
|
|
|
align_hole(&hole_index, &hole_end);
|
|
hole_len = hole_end - hole_index;
|
|
|
|
hole_addr_start = hole_index; /* TODO: Fix this to something better */
|
|
|
|
find_segment_addr_min_max(read_word(dynstr->sh_offset),
|
|
&hole_addr_remap_start, &hole_addr_remap_end);
|
|
|
|
/*
|
|
printf("Hole remap: 0x%lx - 0x%lx\n", hole_addr_remap_start, hole_addr_remap_end);
|
|
|
|
printf("hole: %lu - %lu (%lu bytes)\n", hole_index, hole_end, hole_len);
|
|
printf("hole: 0x%lx - 0x%lx (0x%lx bytes)\n", hole_index, hole_end, hole_len);
|
|
*/
|
|
|
|
/* 2. Change all section and segment sizes and offsets: */
|
|
remap_symtab(dynsym);
|
|
if (symtab)
|
|
remap_symtab(symtab);
|
|
|
|
if (machine_type == EM_386)
|
|
remap_i386_got();
|
|
if (machine_type == EM_PPC)
|
|
remap_ppc_got();
|
|
|
|
remap_dynamic(dynamic, new_dynstr_size);
|
|
remap_sections(); /* After this line the section headers are wrong */
|
|
remap_segments();
|
|
remap_elf_header();
|
|
|
|
/* 3. Do the real compacting. */
|
|
|
|
memmove(mapping + hole_index,
|
|
mapping + hole_index + hole_len,
|
|
size - (hole_index + hole_len));
|
|
|
|
munmap(mapping, size);
|
|
|
|
ftruncate(fd, size - hole_len);
|
|
close(fd);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
|