[PATCH] Adding Bi-Endian 32-bit and 64-bit Support to the Grub ELF Parse
From:
Tomohiro B Berry
Subject:
[PATCH] Adding Bi-Endian 32-bit and 64-bit Support to the Grub ELF Parser
Date:
Fri, 10 Jan 2014 11:58:58 -0600
This patch adds bi-endian support for both
32-bit and 64-bit elf files.
It compares the native endianness to the endianness of the elf file, and
swaps the header bytes if necessary. This will allow, for example,
32-bit Big Endian grub to load a 64-bit Little Endian kernel.
+void grub_elf32_byteswap_header (grub_elf_t
elf);
+void grub_elf64_byteswap_header (grub_elf_t
elf);
+grub_err_t grub_elf32_check_version
(grub_elf_t elf);
+grub_err_t grub_elf64_check_version
(grub_elf_t elf);
+
/* 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;
+ /* e_ident is the same for both
64-bit and 32-bit so just load into a 32-bit struct for now */
+ Elf32_Ehdr *e = &elf->ehdr.ehdr32;
+ /* check if it is an ELF image
at all */
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,
N_("invalid arch-independent ELF magic"));
-
+ || e->e_ident[EI_VERSION]
!= EV_CURRENT)
+ return grub_error (GRUB_ERR_BAD_OS,
N_("invalid arch-independent ELF magic"));
+
+ switch (e->e_ident[EI_CLASS])
+ {
+ case ELFCLASS32:
+ if (e->e_ident[EI_DATA]
!= ELFDATA_NATIVE)
+ grub_elf32_byteswap_header
(elf);
+ if (grub_elf32_check_version
(elf) != GRUB_ERR_NONE)
+ return
grub_errno;
+ break;
+ case ELFCLASS64:
+ if (e->e_ident[EI_DATA]
!= ELFDATA_NATIVE)
+ grub_elf64_byteswap_header
(elf);
+ if (grub_elf64_check_version
(elf) != GRUB_ERR_NONE)
+ return
grub_errno;
+ break;
+ default:
+ return
grub_error (GRUB_ERR_BAD_OS, N_("unrecognized ELF class"));
+ break;
+ }
+
return GRUB_ERR_NONE;
}