--- /dev/null
+/* $OpenBSD: elf_hide.c,v 1.1 1997/01/09 04:16:52 rahnds Exp $ */
+
+/*
+ * Copyright (c) 1997 Dale Rahn. All rights reserved.
+ *
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by Dale Rahn.
+ * 4. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <assert.h>
+#include <sys/exec_elf.h>
+
+void load_strtab(Elf32_Ehdr *pehdr, char *pexe);
+void dump_strtab();
+char *get_str(int indx);
+
+void load_symtab(Elf32_Ehdr *pehdr, char *pexe);
+void dump_symtab();
+
+void load_shstr_tab(Elf32_Ehdr *pehdr, char *pexe);
+char *get_shstr(int indx);
+void fprint_shstr(FILE * channel, int indx);
+
+void hide_sym();
+
+void reorder_syms(Elf32_Ehdr *ehdr, Elf32_Shdr *symsect,
+ Elf32_Sym *symtab, int symtabsize, int symtabsecnum);
+
+typedef int Symmap;
+
+void renum_reloc_syms(Elf32_Ehdr *ehdr, Symmap *symmap, int symtabsecnum);
+
+char * pexe;
+elf_hide(int pfile)
+{
+ int i;
+
+ Elf32_Ehdr *pehdr;
+ Elf32_Shdr *pshdr;
+ Elf32_Phdr *pphdr;
+ struct stat sb;
+
+ fstat(pfile, &sb);
+ pexe = mmap(0, sb.st_size, PROT_READ|PROT_WRITE,
+ MAP_FILE | MAP_SHARED, pfile, 0);
+
+ pehdr = (Elf32_Ehdr *)pexe;
+
+#ifdef DEBUG
+ printf("elf header\n");
+ printf("e_type %x\n", pehdr->e_type);
+ printf("e_machine %x\n", pehdr->e_machine);
+ printf("e_version %x\n", pehdr->e_version);
+ printf("e_entry %x\n", pehdr->e_entry);
+ printf("e_phoff %x\n", pehdr->e_phoff);
+ printf("e_shoff %x\n", pehdr->e_shoff);
+ printf("e_flags %x\n", pehdr->e_flags);
+ printf("e_ehsize %x\n", pehdr->e_ehsize);
+ printf("e_phentsize %x\n", pehdr->e_phentsize);
+ printf("e_phnum %x\n", pehdr->e_phnum);
+ printf("e_shentsize %x\n", pehdr->e_shentsize);
+ printf("e_shnum %x\n", pehdr->e_shnum);
+ printf("e_shstrndx %x\n", pehdr->e_shstrndx);
+#endif
+
+ load_shstr_tab(pehdr, pexe);
+#ifdef DEBUG
+ for (i = 0; i < pehdr->e_shnum; i++) {
+ pshdr = (Elf32_Phdr *) (pexe + pehdr->e_shoff +
+ (i * pehdr->e_shentsize));
+
+ printf("section header %d\n",i);
+ printf("sh_name %x ", pshdr->sh_name);
+ fprint_shstr(stdout, pshdr->sh_name);
+ printf("\n");
+ printf("sh_type %x\n", pshdr->sh_type);
+ printf("sh_flags %x\n", pshdr->sh_flags);
+ printf("sh_addr %x\n", pshdr->sh_addr);
+ printf("sh_offset %x\n", pshdr->sh_offset);
+ printf("sh_size %x\n", pshdr->sh_size);
+ printf("sh_link %x\n", pshdr->sh_link);
+ printf("sh_info %x\n", pshdr->sh_info);
+ printf("sh_addralign %x\n", pshdr->sh_addralign);
+ printf("sh_entsize %x\n", pshdr->sh_entsize);
+ }
+#endif /* DEBUG */
+
+#ifdef DEBUG
+ for (i = 0; i < pehdr->e_phnum; i++) {
+ pshdr = (Elf32_Phdr *) (pexe + pehdr->e_phoff +
+ (i * pehdr->e_phentsize);
+
+ printf("program header %d\n", i);
+ printf("p_type %x\n", pphdr->p_type);
+ printf("p_offset %x\n", pphdr->p_offset);
+ printf("p_vaddr %x\n", pphdr->p_vaddr);
+ printf("p_paddr %x\n", pphdr->p_paddr);
+ printf("p_filesz %x\n", pphdr->p_filesz);
+ printf("p_memsz %x\n", pphdr->p_memsz);
+ printf("p_flags %x\n", pphdr->p_flags);
+ printf("p_align %x\n", pphdr->p_align);
+ }
+#endif /* DEBUG */
+#if 0
+ for (i = 0; i < pehdr->e_shnum; i++) {
+ pshdr = (Elf32_Phdr *) (pexe + pehdr->e_shoff +
+ (i * pehdr->e_shentsize);
+ if (0 == strcmp(".strtab", get_shstr(pshdr->sh_name))) {
+ break;
+ }
+ }
+ fprint_shstr(stdout, pshdr->sh_name);
+ printf("\n");
+#endif
+
+ load_strtab(pehdr, pexe);
+ load_symtab(pehdr, pexe);
+
+ munmap(pexe, sb.st_size);
+ close (pfile);
+}
+char *shstrtab;
+
+void
+load_shstr_tab(Elf32_Ehdr *pehdr, char *pexe)
+{
+ Elf32_Shdr *pshdr;
+ shstrtab = NULL;
+ if (pehdr->e_shstrndx == 0) {
+ return;
+ }
+ pshdr = (Elf32_Shdr *)(pexe + pehdr->e_shoff +
+ (pehdr->e_shstrndx * pehdr->e_shentsize));
+
+ shstrtab = (char *)(pexe + pshdr->sh_offset);
+}
+
+void
+fprint_shstr(FILE * channel, int indx)
+{
+ if (shstrtab != NULL) {
+ fprintf(channel, "\"%s\"", &(shstrtab[indx]));
+ }
+ return;
+}
+
+char *
+get_shstr(int indx)
+{
+ return &(shstrtab[indx]);
+}
+
+void
+load_symtab(Elf32_Ehdr *pehdr, char *pexe)
+{
+ Elf32_Sym *symtab;
+ Elf32_Shdr *symsect;
+ int symtabsize;
+ Elf32_Shdr *pshdr;
+ Elf32_Shdr *psymshdr;
+ char *shname;
+ int i;
+ symtab = NULL;
+ for (i = 0; i < pehdr->e_shnum; i++) {
+ pshdr = (Elf32_Shdr *)(pexe + pehdr->e_shoff +
+ (i * pehdr->e_shentsize) );
+ if (SHT_REL != pshdr->sh_type && SHT_RELA != pshdr->sh_type){
+ continue;
+ }
+ psymshdr = (Elf32_Shdr *)(pexe + pehdr->e_shoff +
+ (pshdr->sh_link * pehdr->e_shentsize) );
+#ifdef DEBUG
+ fprint_shstr(stdout, pshdr->sh_name);
+ printf("\n");
+#endif
+ symtab = (Elf32_Sym *)(pexe + psymshdr->sh_offset);
+ symsect = psymshdr;
+ symtabsize = psymshdr->sh_size;
+
+#ifdef DEBUG
+ dump_symtab(symsect, symtab, symtabsize);
+#endif
+ hide_sym(pehdr, symsect, symtab, symtabsize, pshdr->sh_link);
+ }
+
+}
+
+void
+dump_symtab (Elf32_Shdr *symsect, Elf32_Sym *symtab, int symtabsize)
+{
+ int i;
+ Elf32_Sym *psymtab;
+
+ for (i = 0 ; i < (symtabsize/sizeof(Elf32_Sym)); i++) {
+ psymtab = &(symtab[i]);
+ if ((psymtab->st_info & 0xf0) == 0x10 &&
+ (psymtab->st_shndx != SHN_UNDEF)) {
+ printf("symbol %d:\n", i);
+ printf("st_name %x \"%s\"\n", psymtab->st_name,
+ get_str(psymtab->st_name));
+ printf("st_value %x\n", psymtab->st_value);
+ printf("st_size %x\n", psymtab->st_size);
+ printf("st_info %x\n", psymtab->st_info);
+ printf("st_other %x\n", psymtab->st_other);
+ printf("st_shndx %x\n", psymtab->st_shndx);
+ }
+ }
+}
+
+char * strtab;
+int strtabsize;
+void
+load_strtab(Elf32_Ehdr *pehdr, char *pexe)
+{
+ Elf32_Shdr *pshdr;
+ char *shname;
+ int i;
+ strtab = NULL;
+ for (i = 0; i < pehdr->e_shnum; i++) {
+ pshdr = (Elf32_Shdr *) (pexe + pehdr->e_shoff +
+ (i * pehdr->e_shentsize));
+
+ shname = get_shstr(pshdr->sh_name);
+ if (0 == strcmp(".strtab", shname)) {
+ break;
+ }
+ }
+#ifdef DEBUG
+ fprint_shstr(stdout, pshdr->sh_name);
+ printf("\n");
+#endif
+
+ strtab = (char *) (pexe + pshdr->sh_offset);
+
+ strtabsize = pshdr->sh_size;
+
+#ifdef DEBUG
+ dump_strtab();
+#endif
+}
+
+void
+dump_strtab()
+{
+ int index;
+ char *pstr;
+ char *pnstr;
+ int i = 0;
+ index = 0;
+ pstr = strtab;
+ while (index < strtabsize) {
+ printf("string %x: \"%s\"\n",i, pstr);
+ pnstr = (char *) ((int)strchr(pstr, '\0') + 1);
+ index = pnstr - strtab;
+ pstr = pnstr;
+ i++;
+ }
+
+}
+fprint_str(FILE * channel, int indx)
+{
+ if (strtab != NULL) {
+ fprintf(channel, "\"%s\"", &(strtab[indx]));
+ }
+ return;
+}
+char *
+get_str(int indx)
+{
+ return &(strtab[indx]);
+}
+
+int in_keep_list(char *symbol);
+
+void
+hide_sym(Elf32_Ehdr *ehdr, Elf32_Shdr *symsect,
+ Elf32_Sym *symtab, int symtabsize, int symtabsecnum)
+{
+ int i;
+ unsigned char info;
+ Elf32_Sym *psymtab;
+
+ for (i = 0 ; i < (symtabsize/sizeof(Elf32_Sym)); i++) {
+ psymtab = &(symtab[i]);
+ if ((psymtab->st_info & 0xf0) == 0x10 &&
+ (psymtab->st_shndx != SHN_UNDEF)) {
+ if (in_keep_list(get_str(psymtab->st_name))) {
+ continue;
+ }
+#ifdef DEBUG
+ printf("symbol %d:\n", i);
+ printf("st_name %x \"%s\"\n", psymtab->st_name,
+ get_str(psymtab->st_name));
+ printf("st_info %x\n", psymtab->st_info);
+#endif
+ info = psymtab->st_info;
+ info = info & 0xf;
+ psymtab->st_info = info;
+#ifdef DEBUG
+ printf("st_info %x\n", psymtab->st_info);
+#endif
+ }
+ }
+#ifdef DEBUG
+#endif
+ reorder_syms(ehdr, symsect, symtab, symtabsize, symtabsecnum);
+}
+void
+reorder_syms(Elf32_Ehdr *ehdr, Elf32_Shdr *symsect,
+ Elf32_Sym *symtab, int symtabsize, int symtabsecnum)
+{
+ int i;
+ int nsyms;
+ int cursym;
+ Elf32_Sym *tmpsymtab;
+ Symmap *symmap;
+
+
+ nsyms = symtabsize / sizeof(Elf32_Sym);
+
+ tmpsymtab = (Elf32_Sym *)malloc(symtabsize);
+ symmap = (Symmap *)malloc( sizeof(Symmap) * (nsyms));
+
+ assert (NULL != tmpsymtab);
+
+ bcopy (symtab, tmpsymtab, symtabsize);
+
+ cursym = 1;
+ for (i = 1; i < nsyms; i++) {
+ if ((tmpsymtab[i].st_info & 0xf0) == 0x00) {
+#ifdef DEBUG
+ printf("copying l o%d n%d <%s>\n",i, cursym,
+ get_str(tmpsymtab[i].st_name));
+#endif
+ bcopy (&(tmpsymtab[i]),
+ &(symtab[cursym]), sizeof(Elf32_Sym));
+ symmap[i] = cursym;
+ cursym++;
+ }
+ }
+ symsect->sh_info = cursym;
+ for (i = 1; i < nsyms; i++) {
+ if ((tmpsymtab[i].st_info & 0xf0) != 0x00) {
+#ifdef DEBUG
+ printf("copying nl o%d n%d <%s>\n",i, cursym,
+ get_str(tmpsymtab[i].st_name));
+#endif
+ bcopy (&(tmpsymtab[i]),
+ &(symtab[cursym]), sizeof(Elf32_Sym));
+ symmap[i] = cursym;
+ cursym++;
+ }
+ }
+ if (cursym != nsyms) {
+ printf("miscounted symbols somewhere c %d n %d \n",
+ cursym, nsyms);
+ exit (5);
+ }
+ renum_reloc_syms(ehdr, symmap, symtabsecnum);
+ free (tmpsymtab);
+ free (symmap);
+}
+void
+renum_reloc_syms(Elf32_Ehdr *ehdr, Symmap *symmap, int symtabsecnum)
+{
+ Elf32_Shdr *pshdr;
+ int i, j;
+ int num_reloc;
+ Elf32_Rel *prel;
+ Elf32_Rela *prela;
+ int symnum;
+
+ for (i = 0; i < ehdr->e_shnum; i++) {
+ pshdr = (Elf32_Shdr *)(pexe + ehdr->e_shoff +
+ (i * ehdr->e_shentsize) );
+ if ((pshdr->sh_type == SHT_RELA) &&
+ pshdr->sh_link == symtabsecnum)
+ {
+
+#ifdef DEBUG
+ printf ("section %d has rela relocations in symtab\n", i);
+#endif
+ prela = (Elf32_Rela *)(pexe + pshdr->sh_offset);
+ num_reloc = pshdr->sh_size /sizeof (Elf32_Rela);
+ for (j = 0; j < num_reloc; j++) {
+ symnum = ELF32_R_SYM(prela[j].r_info);
+#ifdef DEBUG
+ printf("sym num o %d n %d\n", symnum,
+ symmap[symnum]);
+#endif
+ prela[j].r_info = ELF32_R_INFO (symmap[symnum],
+ ELF32_R_TYPE(prela[j].r_info));
+ }
+
+ }
+ if ((pshdr->sh_type == SHT_REL) &&
+ pshdr->sh_link == symtabsecnum)
+ {
+#ifdef DEBUG
+ printf ("section %d has rel relocations in symtab\n", i);
+#endif
+ prel = (Elf32_Rel *)(pexe + pshdr->sh_offset);
+ num_reloc = pshdr->sh_size /sizeof (Elf32_Rel);
+ for (j = 0; j < num_reloc; j++) {
+ symnum = ELF32_R_SYM(prel[j].r_info);
+#ifdef DEBUG
+ printf("sym num o %d n %d\n", symnum,
+ symmap[symnum]);
+#endif
+ prel[j].r_info = ELF32_R_INFO (symmap[symnum],
+ ELF32_R_TYPE(prel[j].r_info));
+ }
+ }
+ }
+
+}
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