From bf3df4070f4c0530366e9d6f518785f57c5df8b3 Mon Sep 17 00:00:00 2001 From: Paulo Flabiano Smorigo Date: Mon, 26 Oct 2015 22:07:26 +0100 Subject: [PATCH] Implement cross-endian ELF load for powerpc --- grub-core/kern/elf.c | 56 ++++++++++++++++++++++++++++++++++++++++-- grub-core/kern/elfXX.c | 51 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 105 insertions(+), 2 deletions(-) diff --git a/grub-core/kern/elf.c b/grub-core/kern/elf.c index 5f99c43cc..00de36984 100644 --- a/grub-core/kern/elf.c +++ b/grub-core/kern/elf.c @@ -28,6 +28,23 @@ GRUB_MOD_LICENSE ("GPLv3+"); +#if defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275) +#define GRUB_ELF_ENABLE_BI_ENDIAN 1 +#else +#define GRUB_ELF_ENABLE_BI_ENDIAN 0 +#endif + +#if defined(GRUB_CPU_WORDS_BIGENDIAN) +#define GRUB_ELF_NATIVE_ENDIANNESS ELFDATA2MSB +#define GRUB_ELF_OPPOSITE_ENDIANNESS ELFDATA2LSB +#else +#define GRUB_ELF_NATIVE_ENDIANNESS ELFDATA2LSB +#define GRUB_ELF_OPPOSITE_ENDIANNESS ELFDATA2MSB +#endif + +static int grub_elf32_check_endianess_and_bswap_ehdr (grub_elf_t elf); +static int grub_elf64_check_endianess_and_bswap_ehdr (grub_elf_t elf); + /* Check if EHDR is a valid ELF header. */ static grub_err_t grub_elf_check_header (grub_elf_t elf) @@ -38,8 +55,25 @@ grub_elf_check_header (grub_elf_t elf) || 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) + || e->e_ident[EI_VERSION] != EV_CURRENT) + return grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-independent ELF magic")); + + if (grub_elf_is_elf32 (elf)) + { + if (!grub_elf32_check_endianess_and_bswap_ehdr (elf)) { + return grub_error (GRUB_ERR_BAD_OS, "invalid ELF endianness magic"); + } + } + else if (grub_elf_is_elf64 (elf)) + { + if (!grub_elf64_check_endianess_and_bswap_ehdr (elf)) { + return grub_error (GRUB_ERR_BAD_OS, "invalid ELF endianness magic"); + } + } + else + return grub_error (GRUB_ERR_BAD_OS, "unknown ELF class"); + + if (e->e_version != EV_CURRENT) return grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-independent ELF magic")); return GRUB_ERR_NONE; @@ -117,6 +151,9 @@ grub_elf_open (const char *name) } +#define grub_swap_bytes_halfXX grub_swap_bytes16 +#define grub_swap_bytes_wordXX grub_swap_bytes32 + /* 32-bit */ #define ehdrXX ehdr32 #define ELFCLASSXX ELFCLASS32 @@ -127,7 +164,12 @@ 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 +#define grub_swap_bytes_addrXX grub_swap_bytes32 +#define grub_swap_bytes_offXX grub_swap_bytes32 +#define grub_swap_bytes_XwordXX grub_swap_bytes32 +#define grub_elfXX_check_endianess_and_bswap_ehdr grub_elf32_check_endianess_and_bswap_ehdr #include "elfXX.c" @@ -140,7 +182,12 @@ 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 grub_swap_bytes_addrXX +#undef grub_swap_bytes_offXX +#undef grub_swap_bytes_XwordXX +#undef grub_elfXX_check_endianess_and_bswap_ehdr /* 64-bit */ @@ -153,6 +200,11 @@ 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 +#define grub_swap_bytes_addrXX grub_swap_bytes64 +#define grub_swap_bytes_offXX grub_swap_bytes64 +#define grub_swap_bytes_XwordXX grub_swap_bytes64 +#define grub_elfXX_check_endianess_and_bswap_ehdr grub_elf64_check_endianess_and_bswap_ehdr #include "elfXX.c" diff --git a/grub-core/kern/elfXX.c b/grub-core/kern/elfXX.c index 1d0997186..b91c39d9e 100644 --- a/grub-core/kern/elfXX.c +++ b/grub-core/kern/elfXX.c @@ -31,6 +31,25 @@ grub_elfXX_load_phdrs (grub_elf_t elf) return grub_errno; } +#if GRUB_ELF_ENABLE_BI_ENDIAN + if (elf->ehdr.ehdrXX.e_ident[EI_DATA] == GRUB_ELF_OPPOSITE_ENDIANNESS) + { + ElfXX_Phdr *phdr; + for (phdr = elf->phdrs; (char *) phdr < (char *) elf->phdrs + phdrs_size; + phdr = (ElfXX_Phdr *) ((char *) phdr + elf->ehdr.ehdrXX.e_phentsize)) + { + phdr->p_type = grub_swap_bytes_wordXX (phdr->p_type); + phdr->p_flags = grub_swap_bytes_wordXX (phdr->p_flags); + phdr->p_offset = grub_swap_bytes_offXX (phdr->p_offset); + phdr->p_vaddr = grub_swap_bytes_addrXX (phdr->p_vaddr); + phdr->p_paddr = grub_swap_bytes_addrXX (phdr->p_paddr); + phdr->p_filesz = grub_swap_bytes_XwordXX (phdr->p_filesz); + phdr->p_memsz = grub_swap_bytes_XwordXX (phdr->p_memsz); + phdr->p_align = grub_swap_bytes_XwordXX (phdr->p_align); + } + } +#endif /* GRUB_ELF_ENABLE_BI_ENDIAN */ + return GRUB_ERR_NONE; } @@ -154,3 +173,35 @@ grub_elfXX_load (grub_elf_t elf, const char *filename, return grub_errno; } + +static int +grub_elfXX_check_endianess_and_bswap_ehdr (grub_elf_t elf) +{ + ElfXX_Ehdr *e = &(elf->ehdr.ehdrXX); + if (e->e_ident[EI_DATA] == GRUB_ELF_NATIVE_ENDIANNESS) + { + return 1; + } + +#if GRUB_ELF_ENABLE_BI_ENDIAN + if (e->e_ident[EI_DATA] == GRUB_ELF_OPPOSITE_ENDIANNESS) + { + e->e_type = grub_swap_bytes_halfXX (e->e_type); + e->e_machine = grub_swap_bytes_halfXX (e->e_machine); + e->e_version = grub_swap_bytes_wordXX (e->e_version); + e->e_entry = grub_swap_bytes_addrXX (e->e_entry); + e->e_phoff = grub_swap_bytes_offXX (e->e_phoff); + e->e_shoff = grub_swap_bytes_offXX (e->e_shoff); + e->e_flags = grub_swap_bytes_wordXX (e->e_flags); + e->e_ehsize = grub_swap_bytes_halfXX (e->e_ehsize); + e->e_phentsize = grub_swap_bytes_halfXX (e->e_phentsize); + e->e_phnum = grub_swap_bytes_halfXX (e->e_phnum); + e->e_shentsize = grub_swap_bytes_halfXX (e->e_shentsize); + e->e_shnum = grub_swap_bytes_halfXX (e->e_shnum); + e->e_shstrndx = grub_swap_bytes_halfXX (e->e_shstrndx); + return 1; + } +#endif /* GRUB_ELF_ENABLE_BI_ENDIAN */ + + return 0; +}