int
gelf_update_phdr(Elf *e, int ndx, GElf_Phdr *s)
{
int ec, phnum;
void *ehdr;
Elf32_Phdr *ph32;
Elf64_Phdr *ph64;
if (s == NULL || e == NULL || e->e_kind != ELF_K_ELF ||
((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (0);
}
if (e->e_cmd == ELF_C_READ) {
LIBELF_SET_ERROR(MODE, 0);
return (0);
}
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
return (0);
if (ec == ELFCLASS32)
phnum = ((Elf32_Ehdr *) ehdr)->e_phnum;
else
phnum = ((Elf64_Ehdr *) ehdr)->e_phnum;
if (ndx < 0 || ndx > phnum) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (0);
}
(void) elf_flagphdr(e, ELF_C_SET, ELF_F_DIRTY);
if (ec == ELFCLASS64) {
ph64 = e->e_u.e_elf.e_phdr.e_phdr64 + ndx;
*ph64 = *s;
return (1);
}
ph32 = e->e_u.e_elf.e_phdr.e_phdr32 + ndx;
ph32->p_type = s->p_type;
ph32->p_flags = s->p_flags;
LIBELF_COPY_U32(ph32, s, p_offset);
LIBELF_COPY_U32(ph32, s, p_vaddr);
LIBELF_COPY_U32(ph32, s, p_paddr);
LIBELF_COPY_U32(ph32, s, p_filesz);
LIBELF_COPY_U32(ph32, s, p_memsz);
LIBELF_COPY_U32(ph32, s, p_align);
return (1);
}
void *
_libelf_newphdr(Elf *e, int ec, size_t count)
{
void *ehdr, *newphdr, *oldphdr;
size_t msz;
if (e == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) {
LIBELF_SET_ERROR(SEQUENCE, 0);
return (NULL);
}
assert(e->e_class == ec);
assert(ec == ELFCLASS32 || ec == ELFCLASS64);
assert(e->e_version == EV_CURRENT);
msz = _libelf_msize(ELF_T_PHDR, ec, e->e_version);
assert(msz > 0);
newphdr = NULL;
if (count > 0 && (newphdr = calloc(count, msz)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
if (ec == ELFCLASS32) {
if ((oldphdr = (void *) e->e_u.e_elf.e_phdr.e_phdr32) != NULL)
free(oldphdr);
e->e_u.e_elf.e_phdr.e_phdr32 = (Elf32_Phdr *) newphdr;
} else {
if ((oldphdr = (void *) e->e_u.e_elf.e_phdr.e_phdr64) != NULL)
free(oldphdr);
e->e_u.e_elf.e_phdr.e_phdr64 = (Elf64_Phdr *) newphdr;
}
e->e_u.e_elf.e_nphdr = count;
elf_flagphdr(e, ELF_C_SET, ELF_F_DIRTY);
return (newphdr);
}
bool saveSharedLibrary::readNewLib(){
Elf32_Shdr *newsh, *shdr;
Elf_Scn *scn, *newScn;
Elf32_Ehdr *ehdr;
Elf32_Phdr *oldPhdr;
Elf_Data *strdata, *newdata, *olddata;
if ((ehdr = elf32_getehdr(newElf)) == NULL){
fprintf(stderr," FAILED obtaining ehdr readNewLib\n");
return false;
}
if((scn = elf_getscn(newElf, ehdr->e_shstrndx)) != NULL){
if((strdata = elf_getdata(scn, NULL)) == NULL){
fprintf(stderr," Failed obtaining .shstrtab data buffer \n");
return false;
}
}else{
fprintf(stderr," FAILED obtaining .shstrtab scn\n");
}
unsigned int newScnName =0;
scn = NULL;
Elf_Data shstrtabData;
#if defined(i386_unknown_linux2_0) \
|| defined(x86_64_unknown_linux2_4)
/* save the PHDR from the library */
oldPhdr = elf32_getphdr(newElf);
Elf32_Phdr phdrBuffer[ehdr->e_phnum];
/* copy it over to a buffer because, on linux, we will close newElf and reopen it.
This closing of newElf should dealloc the data pointed to by oldPhdr
*/
memcpy(phdrBuffer, oldPhdr, ehdr->e_phnum * ehdr->e_phentsize);
#endif
for (int cnt = 1; (scn = elf_nextscn(newElf, scn)); cnt++) {
//copy sections from newElf to newElf.
shdr = elf32_getshdr(scn);
olddata = elf_getdata(scn,NULL);
if(!strcmp( (char *)strdata->d_buf + shdr->sh_name, ".text")){
textAddr = shdr->sh_addr;
textData = olddata;
textSize = shdr->sh_size;
}
if(!strcmp( (char*) strdata->d_buf + shdr->sh_name, ".shstrtab")){
const char *secname =".dyninst_mutated\0";
shstrtabData.d_size = olddata->d_size+strlen(secname)+1;
newShstrtabData_d_buf = new char[shstrtabData.d_size];
shstrtabData.d_buf = newShstrtabData_d_buf;
memcpy( shstrtabData.d_buf, olddata->d_buf, olddata->d_size);
memcpy(&(((char*) shstrtabData.d_buf)[olddata->d_size]), secname,
strlen(secname)+1);
newScnName = olddata->d_size;
olddata->d_buf = shstrtabData.d_buf;
olddata->d_size = shstrtabData.d_size;
shdr->sh_size +=strlen(secname)+1;
/* if the section header table is past this section in the
ELF file, calculate the new offset*/
if(ehdr ->e_shoff > shdr->sh_offset){
ehdr->e_shoff += strlen(secname)+1;
}
elf_flagscn(scn,ELF_C_SET,ELF_F_DIRTY);
}
}
ehdr-> e_shnum++;
newScn = elf_newscn(newElf);
newsh = elf32_getshdr(newScn);
newsh->sh_name = newScnName;
newsh->sh_type = SHT_NOBITS; // SHT_NOTE;
newsh->sh_flags=0;
newsh->sh_addr = 0x0;
newsh->sh_offset = shdr->sh_offset;
newsh->sh_size=0;
newsh->sh_link=0;
newsh->sh_info=0;
newsh->sh_addralign = 0x1; //Values 0 and 1 mean the section has no alignment constraints.
newsh->sh_entsize = 0;
newdata = elf_newdata(newScn);
newdata->d_size =0;
newdata->d_buf=0;
elf_update(newElf, ELF_C_NULL);
/* elfutils on linux does not write data back to an ELF file you
have opened correctly. Specifically, if you add a section the
section's section header has space allocated for it in the file
but no data is written to it. lovely, eh?
to combat this, we reopen the file we just closed, and find the
empty section header and fill it with data.
*/
#if defined(i386_unknown_linux2_0) \
|| defined(x86_64_unknown_linux2_4)
elf_update(newElf, ELF_C_WRITE);
elf_end(newElf);
P_close(newfd);
if((newfd = (open(newpathname, O_RDWR)))==-1){
fprintf(stderr,"%s[%d]: cannot open new SO : %s\n",FILE__, __LINE__, newpathname);
perror(" FAIL ");
return false;;
}
if((newElf = elf_begin(newfd, ELF_C_RDWR, NULL)) ==NULL){
fprintf(stderr,"cannot open ELF %s \n", newpathname);
return false;;
}
if ((ehdr = elf32_getehdr(newElf)) == NULL){
fprintf(stderr," FAILED obtaining ehdr readNewLib\n");
return false;
}
if((scn = elf_getscn(newElf, ehdr->e_shstrndx)) != NULL){
if((strdata = elf_getdata(scn, NULL)) == NULL){
fprintf(stderr," Failed obtaining .shstrtab data buffer \n");
return false;
}
}else{
fprintf(stderr," FAILED obtaining .shstrtab scn\n");
}
scn = NULL;
bool foundText=false;
for (int cnt = 1; (scn = elf_nextscn(newElf, scn)); cnt++) {
//copy sections from newElf to newElf.
shdr = elf32_getshdr(scn);
olddata = elf_getdata(scn,NULL);
if(!foundText && !strcmp( (char *)strdata->d_buf + shdr->sh_name, ".text")){
textAddr = shdr->sh_addr;
textData = olddata;
textSize = shdr->sh_size;
elf_flagscn(scn,ELF_C_SET,ELF_F_DIRTY);
foundText = true;
}
}
/**UPDATE THE LAST SHDR **/
memset(shdr,'\0', sizeof(Elf32_Shdr));
shdr->sh_name = newScnName;
shdr->sh_addr = 0x0;
shdr->sh_type = 7;
/* update the PHDR, well just make sure it is reset to
what was in the original library */
Elf32_Phdr *newPhdr = elf32_getphdr(newElf);
memcpy(newPhdr,phdrBuffer, ehdr->e_phnum * ehdr->e_phentsize);
/* be extra sure, set the DIRTY flag */
elf_flagphdr(newElf, ELF_C_SET,ELF_F_DIRTY);
elf_flagscn(scn,ELF_C_SET,ELF_F_DIRTY);
elf_update(newElf, ELF_C_NULL);
#endif
return true;
}
