service_runtime/sel_load_image.c

   1 /*
   2  * Copyright 2008, Google Inc.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *
   9  *     * Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *     * Redistributions in binary form must reproduce the above
  12  * copyright notice, this list of conditions and the following disclaimer
  13  * in the documentation and/or other materials provided with the
  14  * distribution.
  15  *     * Neither the name of Google Inc. nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * NaCl Simple/secure ELF loader (NaCl SEL).
  34  */
  35
  36 #include <string.h>
  37
  38 #include "native_client/include/nacl_elf.h"
  39 #include "native_client/service_runtime/nacl_config.h"
  40 #include "native_client/service_runtime/nacl_check.h"
  41 #include "native_client/service_runtime/nacl_log.h"
  42 #include "native_client/service_runtime/sel_ldr.h"
  43 #include "native_client/service_runtime/sel_util.h"
  44 #include "native_client/service_runtime/tramp.h"
  45
  46 NaClErrorCode NaClLoadImage(struct Gio            *gp,
  47                             struct NaClApp        *nap)
  48 {
  49   int                                 segnum;
  50   Elf32_Phdr                          *php;
  51   uintptr_t                           paddr;
  52   uintptr_t                           end_vaddr;
  53   size_t                              page_pad;
  54
  55   for (segnum = 0; segnum < nap->elf_hdr.e_phnum; ++segnum) {
  56     php = &nap->phdrs[segnum];
  57
  58     /* did we decide that we will load this segment earlier? */
  59     if (0 == (php->p_flags & PF_OS_WILL_LOAD)) {
  60       continue;
  61     }
  62
  63     end_vaddr = php->p_vaddr + php->p_filesz;
  64     /* integer overflow? */
  65     if (end_vaddr < php->p_vaddr) {
  66       NaClLog(LOG_FATAL, "parameter error should have been detected already\n");
  67     }
  68     /*
  69      * is the end virtual address within the NaCl application's
  70      * address space?  if it is, it implies that the start virtual
  71      * address is also.
  72      */
  73     if (end_vaddr >= (1U << nap->addr_bits)) {
  74       NaClLog(LOG_FATAL, "parameter error should have been detected already\n");
  75     }
  76
  77     if (php->p_flags & PF_X)
  78       paddr = nap->code_mem_start + php->p_vaddr;
  79     else
  80       paddr = nap->data_mem_start + php->p_vaddr;
  81
  82     if ((*gp->vtbl->Seek)(gp, php->p_offset, SEEK_SET) == -1) {
  83       return LOAD_SEGMENT_BAD_PARAM;
  84     }
  85     if ((Elf32_Word) (*gp->vtbl->Read)(gp, (void *) paddr, php->p_filesz)
  86         != php->p_filesz) {
  87       return LOAD_SEGMENT_BAD_PARAM;
  88     }
  89     /* region from p_filesz to p_memsz should already be zero filled */
  90   }
  91
  92   /* MarkS: wouldn't it be better to pad before verifying and verify
  93      the padding? */
  94   /*
  95    * fill from text_region_bytes to end of that page with halt
  96    * instruction, which is one byte in size.
  97    */
  98   page_pad = NaClRoundPage(nap->text_region_end) - nap->text_region_end;
  99   CHECK(page_pad < NACL_PAGESIZE);
 100
 101   memset((void *) (nap->code_mem_start
 102                    + nap->text_region_end),
 103          NACL_HALT_OPCODE,
 104          page_pad);
 105   nap->text_region_end += page_pad;
 106
 107   return LOAD_OK;
 108 }