diff options
Diffstat (limited to 'grub-core/kern/elf.c')
| -rw-r--r-- | grub-core/kern/elf.c | 488 |
1 files changed, 488 insertions, 0 deletions
diff --git a/grub-core/kern/elf.c b/grub-core/kern/elf.c new file mode 100644 index 0000000..9c7b8ce --- /dev/null +++ b/grub-core/kern/elf.c @@ -0,0 +1,488 @@ +/* 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/misc.h> +#include <grub/mm.h> +#include <grub/dl.h> + +GRUB_MOD_LICENSE ("GPLv3+"); + +/* 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_file_open (name); + 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, grub_uint32_t *max_align) +{ + Elf32_Addr segments_start = (Elf32_Addr) -1; + Elf32_Addr segments_end = 0; + int nr_phdrs = 0; + grub_uint32_t curr_align = 1; + + /* 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; + if (curr_align < phdr->p_align) + curr_align = phdr->p_align; + 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; + if (max_align) + *max_align = curr_align; + 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, grub_uint64_t *max_align) +{ + Elf64_Addr segments_start = (Elf64_Addr) -1; + Elf64_Addr segments_end = 0; + int nr_phdrs = 0; + grub_uint64_t curr_align = 1; + + /* 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; + if (curr_align < phdr->p_align) + curr_align = phdr->p_align; + 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; + if (max_align) + *max_align = curr_align; + 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; +} |