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 # define Elf_Shdr       Elf32_Shdr
  26 #elif defined(MULTIBOOT_LOAD_ELF64)
  27 # define XX             64
  28 # define E_MACHINE      MULTIBOOT_ELF64_MACHINE
  29 # define ELFCLASSXX     ELFCLASS64
  30 # define Elf_Ehdr       Elf64_Ehdr
  31 # define Elf_Phdr       Elf64_Phdr
  32 # define Elf_Shdr       Elf64_Shdr
  33 #else
  34 #error "I'm confused"
  35 #endif
  36
  37 #include <grub/i386/relocator.h>
  38
  39 #define CONCAT(a,b)     CONCAT_(a, b)
  40 #define CONCAT_(a,b)    a ## b
  41
  42 /* Check if BUFFER contains ELF32 (or ELF64).  */
  43 static int
  44 CONCAT(grub_multiboot_is_elf, XX) (void *buffer)
  45 {
  46   Elf_Ehdr *ehdr = (Elf_Ehdr *) buffer;
  47
  48   return ehdr->e_ident[EI_CLASS] == ELFCLASSXX;
  49 }
  50
  51 static grub_err_t
  52 CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer)
  53 {
  54   Elf_Ehdr *ehdr = (Elf_Ehdr *) buffer;
  55   char *phdr_base;
  56   int i;
  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   /* Load every loadable segment in memory.  */
  91   for (i = 0; i < ehdr->e_phnum; i++)
  92     {
  93       if (phdr(i)->p_type == PT_LOAD)
  94         {
  95           grub_err_t err;
  96           void *source;
  97
  98           grub_dprintf ("multiboot_loader", "segment %d: paddr=0x%lx, memsz=0x%lx, vaddr=0x%lx\n",
  99                         i, (long) phdr(i)->p_paddr, (long) phdr(i)->p_memsz, (long) phdr(i)->p_vaddr);
 100
 101           {
 102             grub_relocator_chunk_t ch;
 103             err = grub_relocator_alloc_chunk_addr (grub_multiboot_relocator,
 104                                                    &ch, phdr(i)->p_paddr,
 105                                                    phdr(i)->p_memsz);
 106             if (err)
 107               {
 108                 grub_dprintf ("multiboot_loader", "Error loading phdr %d\n", i);
 109                 return err;
 110               }
 111             source = get_virtual_current_address (ch);
 112           }
 113
 114           if (phdr(i)->p_filesz != 0)
 115             {
 116               if (grub_file_seek (file, (grub_off_t) phdr(i)->p_offset)
 117                   == (grub_off_t) -1)
 118                 return grub_error (GRUB_ERR_BAD_OS,
 119                                    "invalid offset in program header");
 120
 121               if (grub_file_read (file, source, phdr(i)->p_filesz)
 122                   != (grub_ssize_t) phdr(i)->p_filesz)
 123                 return grub_error (GRUB_ERR_BAD_OS,
 124                                    "couldn't read segment from file");
 125             }
 126
 127           if (phdr(i)->p_filesz < phdr(i)->p_memsz)
 128             grub_memset ((grub_uint8_t *) source + phdr(i)->p_filesz, 0,
 129                          phdr(i)->p_memsz - phdr(i)->p_filesz);
 130         }
 131     }
 132
 133   for (i = 0; i < ehdr->e_phnum; i++)
 134     if (phdr(i)->p_vaddr <= ehdr->e_entry
 135         && phdr(i)->p_vaddr + phdr(i)->p_memsz > ehdr->e_entry)
 136       {
 137         grub_multiboot_payload_eip = (ehdr->e_entry - phdr(i)->p_vaddr)
 138           + phdr(i)->p_paddr;
 139         break;
 140       }
 141
 142   if (i == ehdr->e_phnum)
 143     return grub_error (GRUB_ERR_BAD_OS, "entry point isn't in a segment");
 144
 145 #if defined (__i386__) || defined (__x86_64__)
 146
 147 #elif defined (__mips)
 148   grub_multiboot_payload_eip |= 0x80000000;
 149 #else
 150 #error Please complete this
 151 #endif
 152
 153   if (ehdr->e_shnum)
 154     {
 155       grub_uint8_t *shdr, *shdrptr;
 156
 157       shdr = grub_malloc (ehdr->e_shnum * ehdr->e_shentsize);
 158       if (!shdr)
 159         return grub_errno;
 160
 161       if (grub_file_seek (file, ehdr->e_shoff) == (grub_off_t) -1)
 162         return grub_error (GRUB_ERR_BAD_OS,
 163                            "invalid offset to section headers");
 164
 165       if (grub_file_read (file, shdr, ehdr->e_shnum * ehdr->e_shentsize)
 166               != (grub_ssize_t) ehdr->e_shnum * ehdr->e_shentsize)
 167         return grub_error (GRUB_ERR_BAD_OS,
 168                            "couldn't read sections headers from file");
 169
 170       for (shdrptr = shdr, i = 0; i < ehdr->e_shnum;
 171            shdrptr += ehdr->e_shentsize, i++)
 172         {
 173           Elf_Shdr *sh = (Elf_Shdr *) shdrptr;
 174           void *src;
 175           grub_addr_t target;
 176           grub_err_t err;
 177
 178           /* This section is a loaded section,
 179              so we don't care.  */
 180           if (sh->sh_addr != 0)
 181             continue;
 182
 183           /* This section is empty, so we don't care.  */
 184           if (sh->sh_size == 0)
 185             continue;
 186
 187           {
 188             grub_relocator_chunk_t ch;
 189             err = grub_relocator_alloc_chunk_align (grub_multiboot_relocator,
 190                                                     &ch, 0,
 191                                                     (0xffffffff - sh->sh_size)
 192                                                     + 1, sh->sh_size,
 193                                                     sh->sh_addralign,
 194                                                     GRUB_RELOCATOR_PREFERENCE_NONE);
 195             if (err)
 196               {
 197                 grub_dprintf ("multiboot_loader", "Error loading shdr %d\n", i);
 198                 return err;
 199               }
 200             src = get_virtual_current_address (ch);
 201             target = get_physical_target_address (ch);
 202           }
 203
 204           if (grub_file_seek (file, sh->sh_offset) == (grub_off_t) -1)
 205             return grub_error (GRUB_ERR_BAD_OS,
 206                                "invalid offset in section header");
 207
 208           if (grub_file_read (file, src, sh->sh_size)
 209               != (grub_ssize_t) sh->sh_size)
 210             return grub_error (GRUB_ERR_BAD_OS,
 211                                "couldn't read segment from file");
 212           sh->sh_addr = target;
 213         }
 214       grub_multiboot_add_elfsyms (ehdr->e_shnum, ehdr->e_shentsize,
 215                                   ehdr->e_shstrndx, shdr);
 216     }
 217
 218 #undef phdr
 219
 220   return grub_errno;
 221 }
 222
 223 #undef XX
 224 #undef E_MACHINE
 225 #undef ELFCLASSXX
 226 #undef Elf_Ehdr
 227 #undef Elf_Phdr
 228 #undef Elf_Shdr