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.
Regards,
Tomo Berry
diff --git a/grub-core/kern/elf.c b/grub-core/kern/elf.c
index 5f99c43..3326cd7 100644
--- a/grub-core/kern/elf.c
+++ b/grub-core/kern/elf.c
@@ -28,20 +28,45 @@
GRUB_MOD_LICENSE ("GPLv3+");
+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;
}
@@ -127,7 +152,16 @@ grub_elf_open (const char *name)
#define grub_elf_is_elfXX grub_elf_is_elf32
#define grub_elfXX_load_phdrs grub_elf32_load_phdrs
#define ElfXX_Phdr Elf32_Phdr
+#define ElfXX_Ehdr Elf32_Ehdr
#define grub_uintXX_t grub_uint32_t
+/* for phdr/ehdr byte swaps */
+#define byte_swap_halfXX grub_swap_bytes16
+#define byte_swap_wordXX grub_swap_bytes32
+#define byte_swap_addrXX grub_swap_bytes32
+#define byte_swap_offXX grub_swap_bytes32
+#define byte_swap_XwordXX byte_swap_wordXX /* the 64-bit phdr uses Xwords
and the 32-bit uses words */
+#define grub_elfXX_byteswap_header grub_elf32_byteswap_header
+#define grub_elfXX_check_version grub_elf32_check_version
#include "elfXX.c"
@@ -140,7 +174,15 @@ grub_elf_open (const char *name)
#undef grub_elf_is_elfXX
#undef grub_elfXX_load_phdrs
#undef ElfXX_Phdr
+#undef ElfXX_Ehdr
#undef grub_uintXX_t
+#undef byte_swap_halfXX
+#undef byte_swap_wordXX
+#undef byte_swap_addrXX
+#undef byte_swap_offXX
+#undef byte_swap_XwordXX
+#undef grub_elfXX_byteswap_header
+#undef grub_elfXX_check_version
/* 64-bit */
@@ -153,6 +195,16 @@ grub_elf_open (const char *name)
#define grub_elf_is_elfXX grub_elf_is_elf64
#define grub_elfXX_load_phdrs grub_elf64_load_phdrs
#define ElfXX_Phdr Elf64_Phdr
+#define ElfXX_Ehdr Elf64_Ehdr
#define grub_uintXX_t grub_uint64_t
+/* for phdr/ehdr byte swaps */
+#define byte_swap_halfXX grub_swap_bytes16
+#define byte_swap_wordXX grub_swap_bytes32
+#define byte_swap_addrXX grub_swap_bytes64
+#define byte_swap_offXX grub_swap_bytes64
+#define byte_swap_XwordXX grub_swap_bytes64
+#define grub_elfXX_byteswap_header grub_elf64_byteswap_header
+#define grub_elfXX_check_version grub_elf64_check_version
#include "elfXX.c"
+
diff --git a/grub-core/kern/elfXX.c b/grub-core/kern/elfXX.c
index 2e45449..09062ce 100644
--- a/grub-core/kern/elfXX.c
+++ b/grub-core/kern/elfXX.c
@@ -154,3 +154,47 @@ grub_elfXX_load (grub_elf_t elf, const char
*filename,
return grub_errno;
}
+
+void
+grub_elfXX_byteswap_header (grub_elf_t elf)
+{
+ ElfXX_Ehdr *e = &(elf->ehdr.ehdrXX);
+ ElfXX_Phdr *phdr;
+
+ e->e_type = byte_swap_halfXX (e->e_type);
+ e->e_machine = byte_swap_halfXX (e->e_machine);
+ e->e_version = byte_swap_wordXX (e->e_version);
+ e->e_entry = byte_swap_addrXX (e->e_entry);
+ e->e_phoff = byte_swap_offXX (e->e_phoff);
+ e->e_shoff = byte_swap_offXX (e->e_shoff);
+ e->e_flags = byte_swap_wordXX (e->e_flags);
+ e->e_ehsize = byte_swap_halfXX (e->e_ehsize);
+ e->e_phentsize = byte_swap_halfXX (e->e_phentsize);
+ e->e_phnum = byte_swap_halfXX (e->e_phnum);
+ e->e_shentsize = byte_swap_halfXX (e->e_shentsize);
+ e->e_shnum = byte_swap_halfXX (e->e_shnum);
+ e->e_shstrndx = byte_swap_halfXX (e->e_shstrndx);
+
+ FOR_ELFXX_PHDRS (elf,phdr)
+ {
+ phdr->p_type = byte_swap_wordXX (phdr->p_type);
+ phdr->p_flags = byte_swap_wordXX (phdr->p_flags);
+ phdr->p_offset = byte_swap_offXX (phdr->p_offset);
+ phdr->p_vaddr = byte_swap_addrXX (phdr->p_vaddr);
+ phdr->p_paddr = byte_swap_addrXX (phdr->p_paddr);
+ phdr->p_filesz = byte_swap_XwordXX (phdr->p_filesz);
+ phdr->p_memsz = byte_swap_XwordXX (phdr->p_memsz);
+ phdr->p_align = byte_swap_XwordXX (phdr->p_align);
+ }
+
+}
+
+grub_err_t
+grub_elfXX_check_version (grub_elf_t elf)
+{
+ if (elf->ehdr.ehdrXX.e_version != EV_CURRENT)
+ return grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-independent ELF
magic"));
+
+ return GRUB_ERR_NONE;
+}
+
diff --git a/include/grub/elf.h b/include/grub/elf.h
index 140d24d..d5adf3f 100644
--- a/include/grub/elf.h
+++ b/include/grub/elf.h
@@ -56,6 +56,13 @@ typedef grub_uint16_t Elf64_Section;
typedef Elf32_Half Elf32_Versym;
typedef Elf64_Half Elf64_Versym;
+/* Define the native endianness */
+
+#ifdef GRUB_CPU_WORDS_BIGENDIAN
+#define ELFDATA_NATIVE ELFDATA2MSB
+#else
+#define ELFDATA_NATIVE ELFDATA2LSB
+#endif
/* The ELF file header. This appears at the start of every ELF file. */_______________________________________________
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