grub/kern/elf.c
2010-01-20 11:48:36 +01:00

480 lines
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/* elf.c - load ELF files */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2003,2004,2005,2006,2007,2008,2009 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/err.h>
#include <grub/elf.h>
#include <grub/elfload.h>
#include <grub/file.h>
#include <grub/gzio.h>
#include <grub/misc.h>
#include <grub/mm.h>
/* Check if EHDR is a valid ELF header. */
static grub_err_t
grub_elf_check_header (grub_elf_t elf)
{
Elf32_Ehdr *e = &elf->ehdr.ehdr32;
if (e->e_ident[EI_MAG0] != ELFMAG0
|| e->e_ident[EI_MAG1] != ELFMAG1
|| e->e_ident[EI_MAG2] != ELFMAG2
|| e->e_ident[EI_MAG3] != ELFMAG3
|| e->e_ident[EI_VERSION] != EV_CURRENT
|| e->e_version != EV_CURRENT)
return grub_error (GRUB_ERR_BAD_OS, "invalid arch independent ELF magic");
return GRUB_ERR_NONE;
}
grub_err_t
grub_elf_close (grub_elf_t elf)
{
grub_file_t file = elf->file;
grub_free (elf->phdrs);
grub_free (elf);
if (file)
grub_file_close (file);
return grub_errno;
}
grub_elf_t
grub_elf_file (grub_file_t file)
{
grub_elf_t elf;
elf = grub_zalloc (sizeof (*elf));
if (! elf)
return 0;
elf->file = file;
if (grub_file_seek (elf->file, 0) == (grub_off_t) -1)
goto fail;
if (grub_file_read (elf->file, &elf->ehdr, sizeof (elf->ehdr))
!= sizeof (elf->ehdr))
{
grub_error_push ();
grub_error (GRUB_ERR_READ_ERROR, "cannot read ELF header");
goto fail;
}
if (grub_elf_check_header (elf))
goto fail;
return elf;
fail:
grub_free (elf->phdrs);
grub_free (elf);
return 0;
}
grub_elf_t
grub_elf_open (const char *name)
{
grub_file_t file;
grub_elf_t elf;
file = grub_gzfile_open (name, 1);
if (! file)
return 0;
elf = grub_elf_file (file);
if (! elf)
grub_file_close (file);
return elf;
}
/* 32-bit */
int
grub_elf_is_elf32 (grub_elf_t elf)
{
return elf->ehdr.ehdr32.e_ident[EI_CLASS] == ELFCLASS32;
}
static grub_err_t
grub_elf32_load_phdrs (grub_elf_t elf)
{
grub_ssize_t phdrs_size;
phdrs_size = elf->ehdr.ehdr32.e_phnum * elf->ehdr.ehdr32.e_phentsize;
grub_dprintf ("elf", "Loading program headers at 0x%llx, size 0x%lx.\n",
(unsigned long long) elf->ehdr.ehdr32.e_phoff,
(unsigned long) phdrs_size);
elf->phdrs = grub_malloc (phdrs_size);
if (! elf->phdrs)
return grub_errno;
if ((grub_file_seek (elf->file, elf->ehdr.ehdr32.e_phoff) == (grub_off_t) -1)
|| (grub_file_read (elf->file, elf->phdrs, phdrs_size) != phdrs_size))
{
grub_error_push ();
return grub_error (GRUB_ERR_READ_ERROR, "cannot read program headers");
}
return GRUB_ERR_NONE;
}
grub_err_t
grub_elf32_phdr_iterate (grub_elf_t elf,
int NESTED_FUNC_ATTR (*hook) (grub_elf_t, Elf32_Phdr *, void *),
void *hook_arg)
{
Elf32_Phdr *phdrs;
unsigned int i;
if (! elf->phdrs)
if (grub_elf32_load_phdrs (elf))
return grub_errno;
phdrs = elf->phdrs;
for (i = 0; i < elf->ehdr.ehdr32.e_phnum; i++)
{
Elf32_Phdr *phdr = phdrs + i;
grub_dprintf ("elf",
"Segment %u: type 0x%x paddr 0x%lx memsz 0x%lx "
"filesz %lx\n",
i, phdr->p_type,
(unsigned long) phdr->p_paddr,
(unsigned long) phdr->p_memsz,
(unsigned long) phdr->p_filesz);
if (hook (elf, phdr, hook_arg))
break;
}
return grub_errno;
}
/* Calculate the amount of memory spanned by the segments. */
grub_size_t
grub_elf32_size (grub_elf_t elf, Elf32_Addr *base)
{
Elf32_Addr segments_start = (Elf32_Addr) -1;
Elf32_Addr segments_end = 0;
int nr_phdrs = 0;
/* Run through the program headers to calculate the total memory size we
* should claim. */
auto int NESTED_FUNC_ATTR calcsize (grub_elf_t _elf, Elf32_Phdr *phdr, void *_arg);
int NESTED_FUNC_ATTR calcsize (grub_elf_t _elf __attribute__ ((unused)),
Elf32_Phdr *phdr,
void *_arg __attribute__ ((unused)))
{
/* Only consider loadable segments. */
if (phdr->p_type != PT_LOAD)
return 0;
nr_phdrs++;
if (phdr->p_paddr < segments_start)
segments_start = phdr->p_paddr;
if (phdr->p_paddr + phdr->p_memsz > segments_end)
segments_end = phdr->p_paddr + phdr->p_memsz;
return 0;
}
grub_elf32_phdr_iterate (elf, calcsize, 0);
if (base)
*base = 0;
if (nr_phdrs == 0)
{
grub_error (GRUB_ERR_BAD_OS, "no program headers present");
return 0;
}
if (segments_end < segments_start)
{
/* Very bad addresses. */
grub_error (GRUB_ERR_BAD_OS, "bad program header load addresses");
return 0;
}
if (base)
*base = segments_start;
return segments_end - segments_start;
}
/* Load every loadable segment into memory specified by `_load_hook'. */
grub_err_t
grub_elf32_load (grub_elf_t _elf, grub_elf32_load_hook_t _load_hook,
grub_addr_t *base, grub_size_t *size)
{
grub_addr_t load_base = (grub_addr_t) -1ULL;
grub_size_t load_size = 0;
grub_err_t err;
auto int NESTED_FUNC_ATTR grub_elf32_load_segment (grub_elf_t elf, Elf32_Phdr *phdr, void *hook);
int NESTED_FUNC_ATTR grub_elf32_load_segment (grub_elf_t elf, Elf32_Phdr *phdr, void *hook)
{
grub_elf32_load_hook_t load_hook = (grub_elf32_load_hook_t) hook;
grub_addr_t load_addr;
int do_load = 1;
load_addr = phdr->p_paddr;
if (load_hook && load_hook (phdr, &load_addr, &do_load))
return 1;
if (! do_load)
return 0;
if (load_addr < load_base)
load_base = load_addr;
grub_dprintf ("elf", "Loading segment at 0x%llx, size 0x%llx\n",
(unsigned long long) load_addr,
(unsigned long long) phdr->p_memsz);
if (grub_file_seek (elf->file, phdr->p_offset) == (grub_off_t) -1)
{
grub_error_push ();
return grub_error (GRUB_ERR_BAD_OS,
"invalid offset in program header");
}
if (phdr->p_filesz)
{
grub_ssize_t read;
read = grub_file_read (elf->file, (void *) load_addr, phdr->p_filesz);
if (read != (grub_ssize_t) phdr->p_filesz)
{
/* XXX How can we free memory from `load_hook'? */
grub_error_push ();
return grub_error (GRUB_ERR_BAD_OS,
"couldn't read segment from file: "
"wanted 0x%lx bytes; read 0x%lx bytes",
phdr->p_filesz, read);
}
}
if (phdr->p_filesz < phdr->p_memsz)
grub_memset ((void *) (long) (load_addr + phdr->p_filesz),
0, phdr->p_memsz - phdr->p_filesz);
load_size += phdr->p_memsz;
return 0;
}
err = grub_elf32_phdr_iterate (_elf, grub_elf32_load_segment, _load_hook);
if (base)
*base = load_base;
if (size)
*size = load_size;
return err;
}
/* 64-bit */
int
grub_elf_is_elf64 (grub_elf_t elf)
{
return elf->ehdr.ehdr64.e_ident[EI_CLASS] == ELFCLASS64;
}
static grub_err_t
grub_elf64_load_phdrs (grub_elf_t elf)
{
grub_ssize_t phdrs_size;
phdrs_size = elf->ehdr.ehdr64.e_phnum * elf->ehdr.ehdr64.e_phentsize;
grub_dprintf ("elf", "Loading program headers at 0x%llx, size 0x%lx.\n",
(unsigned long long) elf->ehdr.ehdr64.e_phoff,
(unsigned long) phdrs_size);
elf->phdrs = grub_malloc (phdrs_size);
if (! elf->phdrs)
return grub_errno;
if ((grub_file_seek (elf->file, elf->ehdr.ehdr64.e_phoff) == (grub_off_t) -1)
|| (grub_file_read (elf->file, elf->phdrs, phdrs_size) != phdrs_size))
{
grub_error_push ();
return grub_error (GRUB_ERR_READ_ERROR, "cannot read program headers");
}
return GRUB_ERR_NONE;
}
grub_err_t
grub_elf64_phdr_iterate (grub_elf_t elf,
int NESTED_FUNC_ATTR (*hook) (grub_elf_t, Elf64_Phdr *, void *),
void *hook_arg)
{
Elf64_Phdr *phdrs;
unsigned int i;
if (! elf->phdrs)
if (grub_elf64_load_phdrs (elf))
return grub_errno;
phdrs = elf->phdrs;
for (i = 0; i < elf->ehdr.ehdr64.e_phnum; i++)
{
Elf64_Phdr *phdr = phdrs + i;
grub_dprintf ("elf",
"Segment %u: type 0x%x paddr 0x%lx memsz 0x%lx "
"filesz %lx\n",
i, phdr->p_type,
(unsigned long) phdr->p_paddr,
(unsigned long) phdr->p_memsz,
(unsigned long) phdr->p_filesz);
if (hook (elf, phdr, hook_arg))
break;
}
return grub_errno;
}
/* Calculate the amount of memory spanned by the segments. */
grub_size_t
grub_elf64_size (grub_elf_t elf, Elf64_Addr *base)
{
Elf64_Addr segments_start = (Elf64_Addr) -1;
Elf64_Addr segments_end = 0;
int nr_phdrs = 0;
/* Run through the program headers to calculate the total memory size we
* should claim. */
auto int NESTED_FUNC_ATTR calcsize (grub_elf_t _elf, Elf64_Phdr *phdr, void *_arg);
int NESTED_FUNC_ATTR calcsize (grub_elf_t _elf __attribute__ ((unused)),
Elf64_Phdr *phdr,
void *_arg __attribute__ ((unused)))
{
/* Only consider loadable segments. */
if (phdr->p_type != PT_LOAD)
return 0;
nr_phdrs++;
if (phdr->p_paddr < segments_start)
segments_start = phdr->p_paddr;
if (phdr->p_paddr + phdr->p_memsz > segments_end)
segments_end = phdr->p_paddr + phdr->p_memsz;
return 0;
}
grub_elf64_phdr_iterate (elf, calcsize, 0);
if (base)
*base = 0;
if (nr_phdrs == 0)
{
grub_error (GRUB_ERR_BAD_OS, "no program headers present");
return 0;
}
if (segments_end < segments_start)
{
/* Very bad addresses. */
grub_error (GRUB_ERR_BAD_OS, "bad program header load addresses");
return 0;
}
if (base)
*base = segments_start;
return segments_end - segments_start;
}
/* Load every loadable segment into memory specified by `_load_hook'. */
grub_err_t
grub_elf64_load (grub_elf_t _elf, grub_elf64_load_hook_t _load_hook,
grub_addr_t *base, grub_size_t *size)
{
grub_addr_t load_base = (grub_addr_t) -1ULL;
grub_size_t load_size = 0;
grub_err_t err;
auto int NESTED_FUNC_ATTR grub_elf64_load_segment (grub_elf_t elf, Elf64_Phdr *phdr,
void *hook);
int NESTED_FUNC_ATTR grub_elf64_load_segment (grub_elf_t elf, Elf64_Phdr *phdr, void *hook)
{
grub_elf64_load_hook_t load_hook = (grub_elf64_load_hook_t) hook;
grub_addr_t load_addr;
int do_load = 1;
load_addr = phdr->p_paddr;
if (load_hook && load_hook (phdr, &load_addr, &do_load))
return 1;
if (! do_load)
return 0;
if (load_addr < load_base)
load_base = load_addr;
grub_dprintf ("elf", "Loading segment at 0x%llx, size 0x%llx\n",
(unsigned long long) load_addr,
(unsigned long long) phdr->p_memsz);
if (grub_file_seek (elf->file, phdr->p_offset) == (grub_off_t) -1)
{
grub_error_push ();
return grub_error (GRUB_ERR_BAD_OS,
"invalid offset in program header");
}
if (phdr->p_filesz)
{
grub_ssize_t read;
read = grub_file_read (elf->file, (void *) load_addr, phdr->p_filesz);
if (read != (grub_ssize_t) phdr->p_filesz)
{
/* XXX How can we free memory from `load_hook'? */
grub_error_push ();
return grub_error (GRUB_ERR_BAD_OS,
"couldn't read segment from file: "
"wanted 0x%lx bytes; read 0x%lx bytes",
phdr->p_filesz, read);
}
}
if (phdr->p_filesz < phdr->p_memsz)
grub_memset ((void *) (long) (load_addr + phdr->p_filesz),
0, phdr->p_memsz - phdr->p_filesz);
load_size += phdr->p_memsz;
return 0;
}
err = grub_elf64_phdr_iterate (_elf, grub_elf64_load_segment, _load_hook);
if (base)
*base = load_base;
if (size)
*size = load_size;
return err;
}