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/*
* parse and load elf binaries
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libelf-private.h"
/* ------------------------------------------------------------------------ */
elf_errorstatus elf_init(struct elf_binary *elf, const char *image_input, size_t size)
{
ELF_HANDLE_DECL(elf_shdr) shdr;
uint64_t i, count, section, offset;
if ( !elf_is_elfbinary(image_input, size) )
{
elf_err(elf, "%s: not an ELF binary\n", __FUNCTION__);
return -1;
}
elf_memset_unchecked(elf, 0, sizeof(*elf));
elf->image_base = image_input;
elf->size = size;
elf->ehdr = ELF_MAKE_HANDLE(elf_ehdr, (elf_ptrval)image_input);
elf->class = elf_uval_3264(elf, elf->ehdr, e32.e_ident[EI_CLASS]);
elf->data = elf_uval_3264(elf, elf->ehdr, e32.e_ident[EI_DATA]);
elf->caller_xdest_base = NULL;
elf->caller_xdest_size = 0;
/* Sanity check phdr. */
offset = elf_uval(elf, elf->ehdr, e_phoff) +
elf_uval(elf, elf->ehdr, e_phentsize) * elf_phdr_count(elf);
if ( offset > elf->size )
{
elf_err(elf, "%s: phdr overflow (off %" PRIx64 " > size %lx)\n",
__FUNCTION__, offset, (unsigned long)elf->size);
return -1;
}
/* Sanity check shdr. */
offset = elf_uval(elf, elf->ehdr, e_shoff) +
elf_uval(elf, elf->ehdr, e_shentsize) * elf_shdr_count(elf);
if ( offset > elf->size )
{
elf_err(elf, "%s: shdr overflow (off %" PRIx64 " > size %lx)\n",
__FUNCTION__, offset, (unsigned long)elf->size);
return -1;
}
/* Find section string table. */
section = elf_uval(elf, elf->ehdr, e_shstrndx);
shdr = elf_shdr_by_index(elf, section);
if ( ELF_HANDLE_VALID(shdr) )
elf->sec_strtab = elf_section_start(elf, shdr);
/* Find symbol table and symbol string table. */
count = elf_shdr_count(elf);
for ( i = 0; i < count; i++ )
{
shdr = elf_shdr_by_index(elf, i);
if ( elf_uval(elf, shdr, sh_type) != SHT_SYMTAB )
continue;
elf->sym_tab = shdr;
shdr = elf_shdr_by_index(elf, elf_uval(elf, shdr, sh_link));
if ( !ELF_HANDLE_VALID(shdr) )
{
elf->sym_tab = ELF_INVALID_HANDLE(elf_shdr);
continue;
}
elf->sym_strtab = elf_section_start(elf, shdr);
break;
}
return 0;
}
#ifndef __XEN__
void elf_call_log_callback(struct elf_binary *elf, bool iserr,
const char *fmt,...) {
va_list al;
if (!elf->log_callback)
return;
if (!(iserr || elf->verbose))
return;
va_start(al,fmt);
elf->log_callback(elf, elf->log_caller_data, iserr, fmt, al);
va_end(al);
}
void elf_set_log(struct elf_binary *elf, elf_log_callback *log_callback,
void *log_caller_data, bool verbose)
{
elf->log_callback = log_callback;
elf->log_caller_data = log_caller_data;
elf->verbose = verbose;
}
#else
void elf_set_verbose(struct elf_binary *elf)
{
elf->verbose = 1;
}
#endif
/* Calculate the required additional kernel space for the elf image */
void elf_parse_bsdsyms(struct elf_binary *elf, uint64_t pstart)
{
uint64_t sz;
ELF_HANDLE_DECL(elf_shdr) shdr;
unsigned i, type;
if ( !ELF_HANDLE_VALID(elf->sym_tab) )
return;
pstart = elf_round_up(elf, pstart);
/* Space to store the size of the elf image */
sz = sizeof(uint32_t);
/* Space for the elf and elf section headers */
sz += (elf_uval(elf, elf->ehdr, e_ehsize) +
elf_shdr_count(elf) * elf_uval(elf, elf->ehdr, e_shentsize));
sz = elf_round_up(elf, sz);
/* Space for the symbol and string tables. */
for ( i = 0; i < elf_shdr_count(elf); i++ )
{
shdr = elf_shdr_by_index(elf, i);
type = elf_uval(elf, shdr, sh_type);
if ( (type == SHT_STRTAB) || (type == SHT_SYMTAB) )
sz = elf_round_up(elf, sz + elf_uval(elf, shdr, sh_size));
}
elf->bsd_symtab_pstart = pstart;
elf->bsd_symtab_pend = pstart + sz;
}
static void elf_load_bsdsyms(struct elf_binary *elf)
{
ELF_HANDLE_DECL_NONCONST(elf_ehdr) sym_ehdr;
unsigned long sz;
ELF_PTRVAL_VOID maxva;
ELF_PTRVAL_VOID symbase;
ELF_PTRVAL_VOID symtab_addr;
ELF_HANDLE_DECL_NONCONST(elf_shdr) shdr;
unsigned i, type;
if ( !elf->bsd_symtab_pstart )
return;
#define elf_hdr_elm(_elf, _hdr, _elm, _val) \
do { \
if ( elf_64bit(_elf) ) \
elf_store_field(_elf, _hdr, e64._elm, _val); \
else \
elf_store_field(_elf, _hdr, e32._elm, _val); \
} while ( 0 )
symbase = elf_get_ptr(elf, elf->bsd_symtab_pstart);
symtab_addr = maxva = symbase + sizeof(uint32_t);
/* Set up Elf header. */
sym_ehdr = ELF_MAKE_HANDLE(elf_ehdr, symtab_addr);
sz = elf_uval(elf, elf->ehdr, e_ehsize);
elf_memcpy_safe(elf, ELF_HANDLE_PTRVAL(sym_ehdr), ELF_HANDLE_PTRVAL(elf->ehdr), sz);
maxva += sz; /* no round up */
elf_hdr_elm(elf, sym_ehdr, e_phoff, 0);
elf_hdr_elm(elf, sym_ehdr, e_shoff, elf_uval(elf, elf->ehdr, e_ehsize));
elf_hdr_elm(elf, sym_ehdr, e_phentsize, 0);
elf_hdr_elm(elf, sym_ehdr, e_phnum, 0);
/* Copy Elf section headers. */
shdr = ELF_MAKE_HANDLE(elf_shdr, maxva);
sz = elf_shdr_count(elf) * elf_uval(elf, elf->ehdr, e_shentsize);
elf_memcpy_safe(elf, ELF_HANDLE_PTRVAL(shdr),
ELF_IMAGE_BASE(elf) + elf_uval(elf, elf->ehdr, e_shoff),
sz);
maxva = ELF_OBSOLETE_VOIDP_CAST elf_round_up(elf, (unsigned long)maxva + sz);
for ( i = 0; i < elf_shdr_count(elf); i++ )
{
type = elf_uval(elf, shdr, sh_type);
if ( (type == SHT_STRTAB) || (type == SHT_SYMTAB) )
{
elf_msg(elf, "%s: shdr %i at 0x%"ELF_PRPTRVAL" -> 0x%"ELF_PRPTRVAL"\n", __func__, i,
elf_section_start(elf, shdr), maxva);
sz = elf_uval(elf, shdr, sh_size);
elf_memcpy_safe(elf, maxva, elf_section_start(elf, shdr), sz);
/* Mangled to be based on ELF header location. */
elf_hdr_elm(elf, shdr, sh_offset, maxva - symtab_addr);
maxva = ELF_OBSOLETE_VOIDP_CAST elf_round_up(elf, (unsigned long)maxva + sz);
}
shdr = ELF_MAKE_HANDLE(elf_shdr, ELF_HANDLE_PTRVAL(shdr) +
(unsigned long)elf_uval(elf, elf->ehdr, e_shentsize));
}
/* Write down the actual sym size. */
elf_store_val(elf, uint32_t, symbase, maxva - symtab_addr);
#undef elf_ehdr_elm
}
void elf_parse_binary(struct elf_binary *elf)
{
ELF_HANDLE_DECL(elf_phdr) phdr;
uint64_t low = -1;
uint64_t high = 0;
uint64_t i, count, paddr, memsz;
count = elf_uval(elf, elf->ehdr, e_phnum);
for ( i = 0; i < count; i++ )
{
phdr = elf_phdr_by_index(elf, i);
if ( !elf_phdr_is_loadable(elf, phdr) )
continue;
paddr = elf_uval(elf, phdr, p_paddr);
memsz = elf_uval(elf, phdr, p_memsz);
elf_msg(elf, "%s: phdr: paddr=0x%" PRIx64
" memsz=0x%" PRIx64 "\n", __FUNCTION__, paddr, memsz);
if ( low > paddr )
low = paddr;
if ( high < paddr + memsz )
high = paddr + memsz;
}
elf->pstart = low;
elf->pend = high;
elf_msg(elf, "%s: memory: 0x%" PRIx64 " -> 0x%" PRIx64 "\n",
__FUNCTION__, elf->pstart, elf->pend);
}
void elf_load_binary(struct elf_binary *elf)
{
ELF_HANDLE_DECL(elf_phdr) phdr;
uint64_t i, count, paddr, offset, filesz, memsz;
ELF_PTRVAL_VOID dest;
count = elf_uval(elf, elf->ehdr, e_phnum);
for ( i = 0; i < count; i++ )
{
phdr = elf_phdr_by_index(elf, i);
if ( !elf_phdr_is_loadable(elf, phdr) )
continue;
paddr = elf_uval(elf, phdr, p_paddr);
offset = elf_uval(elf, phdr, p_offset);
filesz = elf_uval(elf, phdr, p_filesz);
memsz = elf_uval(elf, phdr, p_memsz);
dest = elf_get_ptr(elf, paddr);
elf_msg(elf, "%s: phdr %" PRIu64 " at 0x%"ELF_PRPTRVAL" -> 0x%"ELF_PRPTRVAL"\n",
__func__, i, dest, (ELF_PTRVAL_VOID)(dest + filesz));
elf_memcpy_safe(elf, dest, ELF_IMAGE_BASE(elf) + offset, filesz);
elf_memset_safe(elf, dest + filesz, 0, memsz - filesz);
}
elf_load_bsdsyms(elf);
}
ELF_PTRVAL_VOID elf_get_ptr(struct elf_binary *elf, unsigned long addr)
{
return ELF_REALPTR2PTRVAL(elf->dest_base) + addr - elf->pstart;
}
uint64_t elf_lookup_addr(struct elf_binary * elf, const char *symbol)
{
ELF_HANDLE_DECL(elf_sym) sym;
uint64_t value;
sym = elf_sym_by_name(elf, symbol);
if ( !ELF_HANDLE_VALID(sym) )
{
elf_err(elf, "%s: not found: %s\n", __FUNCTION__, symbol);
return -1;
}
value = elf_uval(elf, sym, st_value);
elf_msg(elf, "%s: symbol \"%s\" at 0x%" PRIx64 "\n", __FUNCTION__,
symbol, value);
return value;
}
/*
* Local variables:
* mode: C
* c-set-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
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