Lockpick_RCM/bdk/ianos/elfload/elfload.c

325 lines
6.5 KiB
C

/*
* Copyright © 2018, M4xw
* Copyright © 2014, Owen Shepherd
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include <string.h>
#include "elfload.h"
el_status el_pread(el_ctx *ctx, void *def, size_t nb, size_t offset)
{
return ctx->pread(ctx, def, nb, offset) ? EL_OK : EL_EIO;
}
#define EL_PHOFF(ctx, num) (((ctx)->ehdr.e_phoff + (num) *(ctx)->ehdr.e_phentsize))
el_status el_findphdr(el_ctx *ctx, Elf_Phdr *phdr, uint32_t type, unsigned *i)
{
el_status rv = EL_OK;
for (; *i < ctx->ehdr.e_phnum; (*i)++)
{
if ((rv = el_pread(ctx, phdr, sizeof *phdr, EL_PHOFF(ctx, *i))))
return rv;
if (phdr->p_type == type)
{
return rv;
}
}
*i = -1;
return rv;
}
#define EL_SHOFF(ctx, num) (((ctx)->ehdr.e_shoff + (num) *(ctx)->ehdr.e_shentsize))
el_status el_findshdr(el_ctx *ctx, Elf_Shdr *shdr, uint32_t type, unsigned *i)
{
el_status rv = EL_OK;
for (; *i < ctx->ehdr.e_shnum; (*i)++)
{
if ((rv = el_pread(ctx, shdr, sizeof *shdr, EL_SHOFF(ctx, *i))))
return rv;
if (shdr->sh_type == type)
{
return rv;
}
}
*i = -1;
return rv;
}
el_status el_init(el_ctx *ctx)
{
el_status rv = EL_OK;
if ((rv = el_pread(ctx, &ctx->ehdr, sizeof ctx->ehdr, 0)))
return rv;
/* validate header */
if (!IS_ELF(ctx->ehdr))
return EL_NOTELF;
if (ctx->ehdr.e_ident[EI_CLASS] != ELFCLASS)
return EL_WRONGBITS;
if (ctx->ehdr.e_ident[EI_DATA] != ELFDATATHIS)
return EL_WRONGENDIAN;
if (ctx->ehdr.e_ident[EI_VERSION] != EV_CURRENT)
return EL_NOTELF;
if (ctx->ehdr.e_type != ET_EXEC && ctx->ehdr.e_type != ET_DYN)
return EL_NOTEXEC;
if (ctx->ehdr.e_machine != EM_THIS)
return EL_WRONGARCH;
if (ctx->ehdr.e_version != EV_CURRENT)
return EL_NOTELF;
/* load phdrs */
Elf_Phdr ph;
/* iterate through, calculate extents */
ctx->base_load_paddr = ctx->base_load_vaddr = 0;
ctx->align = 1;
ctx->memsz = 0;
unsigned i = 0;
for (;;)
{
if ((rv = el_findphdr(ctx, &ph, PT_LOAD, &i)))
return rv;
if (i == (unsigned)-1)
break;
Elf_Addr phend = ph.p_vaddr + ph.p_memsz;
if (phend > ctx->memsz)
ctx->memsz = phend;
if (ph.p_align > ctx->align)
ctx->align = ph.p_align;
i++;
}
// Program Header
if (ctx->ehdr.e_type == ET_DYN)
{
i = 0;
if ((rv = el_findphdr(ctx, &ph, PT_DYNAMIC, &i)))
return rv;
if (i == (unsigned)-1)
return EL_NODYN;
ctx->dynoff = ph.p_offset;
ctx->dynsize = ph.p_filesz;
}
else
{
ctx->dynoff = 0;
ctx->dynsize = 0;
}
// Section String Table
if (ctx->ehdr.e_type == ET_DYN)
{
i = ctx->ehdr.e_shstrndx - 1;
if ((rv = el_findshdr(ctx, &ctx->shstr, SHT_STRTAB, &i)))
return rv;
// Reset
i = 0;
if ((rv = el_findshdr(ctx, &ctx->symtab, SHT_SYMTAB, &i)))
return rv;
if (i == (unsigned)-1)
return EL_NODYN;
}
return rv;
}
/*
typedef void* (*el_alloc_cb)(
el_ctx *ctx,
Elf_Addr phys,
Elf_Addr virt,
Elf_Addr size);
*/
el_status el_load(el_ctx *ctx, el_alloc_cb alloc)
{
el_status rv = EL_OK;
/* address deltas */
Elf_Addr pdelta = ctx->base_load_paddr;
Elf_Addr vdelta = ctx->base_load_vaddr;
/* iterate paddrs */
Elf_Phdr ph;
unsigned i = 0;
for (;;)
{
if ((rv = el_findphdr(ctx, &ph, PT_LOAD, &i)))
return rv;
if (i == (unsigned)-1)
break;
Elf_Addr pload = ph.p_paddr + pdelta;
Elf_Addr vload = ph.p_vaddr + vdelta;
/* allocate mem */
char *dest = alloc(ctx, pload, vload, ph.p_memsz);
if (!dest)
return EL_ENOMEM;
EL_DEBUG("Loading seg fileoff %x, vaddr %x to %p\n",
ph.p_offset, ph.p_vaddr, dest);
/* read loaded portion */
if ((rv = el_pread(ctx, dest, ph.p_filesz, ph.p_offset)))
return rv;
/* zero mem-only portion */
memset(dest + ph.p_filesz, 0, ph.p_memsz - ph.p_filesz);
i++;
}
return rv;
}
el_status el_finddyn(el_ctx *ctx, Elf_Dyn *dyn, uint32_t tag)
{
el_status rv = EL_OK;
size_t ndyn = ctx->dynsize / sizeof(Elf_Dyn);
for (unsigned i = 0; i < ndyn; i++)
{
if ((rv = el_pread(ctx, dyn, sizeof *dyn, ctx->dynoff + i * sizeof *dyn)))
return rv;
if (dyn->d_tag == tag)
return EL_OK;
}
dyn->d_tag = DT_NULL;
return EL_OK;
}
el_status el_findrelocs(el_ctx *ctx, el_relocinfo *ri, uint32_t type)
{
el_status rv = EL_OK;
Elf_Dyn rel, relsz, relent;
if ((rv = el_finddyn(ctx, &rel, type)))
return rv;
if ((rv = el_finddyn(ctx, &relsz, type + 1)))
return rv;
if ((rv = el_finddyn(ctx, &relent, type + 2)))
return rv;
if (rel.d_tag == DT_NULL || relsz.d_tag == DT_NULL || relent.d_tag == DT_NULL)
{
ri->entrysize = 0;
ri->tablesize = 0;
ri->tableoff = 0;
}
else
{
ri->tableoff = rel.d_un.d_ptr;
ri->tablesize = relsz.d_un.d_val;
ri->entrysize = relent.d_un.d_val;
}
return rv;
}
extern el_status el_applyrel(el_ctx *ctx, Elf_Rel *rel);
extern el_status el_applyrela(el_ctx *ctx, Elf_RelA *rela);
el_status el_relocate(el_ctx *ctx)
{
el_status rv = EL_OK;
// not dynamic
if (ctx->ehdr.e_type != ET_DYN)
return EL_OK;
char *base = (char *)ctx->base_load_paddr;
el_relocinfo ri;
#ifdef EL_ARCH_USES_REL
if ((rv = el_findrelocs(ctx, &ri, DT_REL)))
return rv;
if (ri.entrysize != sizeof(Elf_Rel) && ri.tablesize)
{
EL_DEBUG("Relocation size %u doesn't match expected %u\n",
ri.entrysize, sizeof(Elf_Rel));
return EL_BADREL;
}
size_t relcnt = ri.tablesize / sizeof(Elf_Rel);
Elf_Rel *reltab = (Elf_Rel *)(base + ri.tableoff);
for (size_t i = 0; i < relcnt; i++)
{
if ((rv = el_applyrel(ctx, &reltab[i])))
return rv;
}
#endif
#ifdef EL_ARCH_USES_RELA
if ((rv = el_findrelocs(ctx, &ri, DT_RELA)))
return rv;
if (ri.entrysize != sizeof(Elf_RelA) && ri.tablesize)
{
EL_DEBUG("Relocation size %u doesn't match expected %u\n",
ri.entrysize, sizeof(Elf_RelA));
return EL_BADREL;
}
size_t relacnt = ri.tablesize / sizeof(Elf_RelA);
Elf_RelA *relatab = (Elf_RelA *)(base + ri.tableoff);
for (size_t i = 0; i < relacnt; i++)
{
if ((rv = el_applyrela(ctx, &relatab[i])))
return rv;
}
#endif
#if !defined(EL_ARCH_USES_REL) && !defined(EL_ARCH_USES_RELA)
#error No relocation type defined!
#endif
return rv;
}