grub-core/loader/multiboot_elfxx.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2007,2008,2009  Free Software Foundation, Inc.
   4  *
   5  *  GRUB is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  GRUB is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #if defined(MULTIBOOT_LOAD_ELF32)
  20 # define XX             32
  21 # define E_MACHINE      MULTIBOOT_ELF32_MACHINE
  22 # define ELFCLASSXX     ELFCLASS32
  23 # define Elf_Ehdr       Elf32_Ehdr
  24 # define Elf_Phdr       Elf32_Phdr
  25 #elif defined(MULTIBOOT_LOAD_ELF64)
  26 # define XX             64
  27 # define E_MACHINE      MULTIBOOT_ELF64_MACHINE
  28 # define ELFCLASSXX     ELFCLASS64
  29 # define Elf_Ehdr       Elf64_Ehdr
  30 # define Elf_Phdr       Elf64_Phdr
  31 #else
  32 #error "I'm confused"
  33 #endif
  34
  35 #include <grub/i386/relocator.h>
  36
  37 #define CONCAT(a,b)     CONCAT_(a, b)
  38 #define CONCAT_(a,b)    a ## b
  39
  40 /* Check if BUFFER contains ELF32 (or ELF64).  */
  41 static int
  42 CONCAT(grub_multiboot_is_elf, XX) (void *buffer)
  43 {
  44   Elf_Ehdr *ehdr = (Elf_Ehdr *) buffer;
  45
  46   return ehdr->e_ident[EI_CLASS] == ELFCLASSXX;
  47 }
  48
  49 static grub_err_t
  50 CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer)
  51 {
  52   Elf_Ehdr *ehdr = (Elf_Ehdr *) buffer;
  53   char *phdr_base;
  54   int lowest_segment = -1, highest_segment = -1;
  55   int i;
  56   grub_size_t code_size;
  57
  58   if (ehdr->e_ident[EI_CLASS] != ELFCLASSXX)
  59     return grub_error (GRUB_ERR_UNKNOWN_OS, "invalid ELF class");
  60
  61   if (ehdr->e_ident[EI_MAG0] != ELFMAG0
  62       || ehdr->e_ident[EI_MAG1] != ELFMAG1
  63       || ehdr->e_ident[EI_MAG2] != ELFMAG2
  64       || ehdr->e_ident[EI_MAG3] != ELFMAG3
  65       || ehdr->e_version != EV_CURRENT
  66       || ehdr->e_ident[EI_DATA] != ELFDATA2LSB
  67       || ehdr->e_machine != E_MACHINE)
  68     return grub_error(GRUB_ERR_UNKNOWN_OS, "no valid ELF header found");
  69
  70   if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
  71     return grub_error (GRUB_ERR_UNKNOWN_OS, "invalid ELF file type");
  72
  73   /* FIXME: Should we support program headers at strange locations?  */
  74   if (ehdr->e_phoff + ehdr->e_phnum * ehdr->e_phentsize > MULTIBOOT_SEARCH)
  75     return grub_error (GRUB_ERR_BAD_OS, "program header at a too high offset");
  76
  77 #if defined (MULTIBOOT_LOAD_ELF64) && defined (__mips)
  78   /* We still in 32-bit mode.  */
  79   if (ehdr->e_entry < 0xffffffff80000000ULL)
  80     return grub_error (GRUB_ERR_BAD_OS, "invalid entry point for ELF64");
  81 #else
  82   /* We still in 32-bit mode.  */
  83   if (ehdr->e_entry > 0xffffffff)
  84     return grub_error (GRUB_ERR_BAD_OS, "invalid entry point for ELF64");
  85 #endif
  86
  87   phdr_base = (char *) buffer + ehdr->e_phoff;
  88 #define phdr(i)                 ((Elf_Phdr *) (phdr_base + (i) * ehdr->e_phentsize))
  89
  90   for (i = 0; i < ehdr->e_phnum; i++)
  91     if (phdr(i)->p_type == PT_LOAD && phdr(i)->p_filesz != 0)
  92       {
  93         /* Beware that segment 0 isn't necessarily loadable */
  94         if (lowest_segment == -1
  95             || phdr(i)->p_paddr < phdr(lowest_segment)->p_paddr)
  96           lowest_segment = i;
  97         if (highest_segment == -1
  98             || phdr(i)->p_paddr > phdr(highest_segment)->p_paddr)
  99           highest_segment = i;
 100       }
 101
 102   if (lowest_segment == -1)
 103     return grub_error (GRUB_ERR_BAD_OS, "ELF contains no loadable segments");
 104
 105   code_size = (phdr(highest_segment)->p_paddr + phdr(highest_segment)->p_memsz) - phdr(lowest_segment)->p_paddr;
 106   grub_multiboot_payload_dest = phdr(lowest_segment)->p_paddr;
 107
 108   grub_multiboot_pure_size += code_size;
 109
 110   grub_multiboot_alloc_mbi = grub_multiboot_get_mbi_size () + 65536;
 111   grub_multiboot_payload_orig
 112     = grub_relocator32_alloc (grub_multiboot_pure_size + grub_multiboot_alloc_mbi);
 113
 114   if (!grub_multiboot_payload_orig)
 115     return grub_errno;
 116
 117   /* Load every loadable segment in memory.  */
 118   for (i = 0; i < ehdr->e_phnum; i++)
 119     {
 120       if (phdr(i)->p_type == PT_LOAD && phdr(i)->p_filesz != 0)
 121         {
 122           char *load_this_module_at = (char *) (grub_multiboot_payload_orig + (long) (phdr(i)->p_paddr - phdr(lowest_segment)->p_paddr));
 123
 124           grub_dprintf ("multiboot_loader", "segment %d: paddr=0x%lx, memsz=0x%lx, vaddr=0x%lx\n",
 125                         i, (long) phdr(i)->p_paddr, (long) phdr(i)->p_memsz, (long) phdr(i)->p_vaddr);
 126
 127           if (grub_file_seek (file, (grub_off_t) phdr(i)->p_offset)
 128               == (grub_off_t) -1)
 129             return grub_error (GRUB_ERR_BAD_OS,
 130                                "invalid offset in program header");
 131
 132           if (grub_file_read (file, load_this_module_at, phdr(i)->p_filesz)
 133               != (grub_ssize_t) phdr(i)->p_filesz)
 134             return grub_error (GRUB_ERR_BAD_OS,
 135                                "couldn't read segment from file");
 136
 137           if (phdr(i)->p_filesz < phdr(i)->p_memsz)
 138             grub_memset (load_this_module_at + phdr(i)->p_filesz, 0,
 139                          phdr(i)->p_memsz - phdr(i)->p_filesz);
 140         }
 141     }
 142
 143   for (i = 0; i < ehdr->e_phnum; i++)
 144     if (phdr(i)->p_vaddr <= ehdr->e_entry
 145         && phdr(i)->p_vaddr + phdr(i)->p_memsz > ehdr->e_entry)
 146       {
 147         grub_multiboot_payload_eip = grub_multiboot_payload_dest
 148           + (ehdr->e_entry - phdr(i)->p_vaddr) + (phdr(i)->p_paddr  - phdr(lowest_segment)->p_paddr);
 149         break;
 150       }
 151
 152   if (i == ehdr->e_phnum)
 153     return grub_error (GRUB_ERR_BAD_OS, "entry point isn't in a segment");
 154
 155 #undef phdr
 156
 157   return grub_errno;
 158 }
 159
 160 #undef XX
 161 #undef E_MACHINE
 162 #undef ELFCLASSXX
 163 #undef Elf_Ehdr
 164 #undef Elf_Phdr