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  1. /*
  2.  * Copyright (C) 2006 Sergey Bondari
  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
  7.  * are 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 copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <elf.h>
  30. #include <debug.h>
  31. #include <arch/types.h>
  32. #include <typedefs.h>
  33. #include <mm/as.h>
  34. #include <mm/frame.h>
  35. #include <mm/slab.h>
  36. #include <print.h>
  37. #include <align.h>
  38. #include <memstr.h>
  39. #include <macros.h>
  40.  
  41. static char *error_codes[] = {
  42.     "no error",
  43.     "invalid image",
  44.     "address space error",
  45.     "incompatible image",
  46.     "unsupported image type",
  47.     "irrecoverable error"
  48. };
  49.  
  50. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  51. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as);
  52. static int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  53.  
  54. /** ELF loader
  55.  *
  56.  * @param header Pointer to ELF header in memory
  57.  * @param as Created and properly mapped address space
  58.  * @return EE_OK on success
  59.  */
  60. int elf_load(elf_header_t *header, as_t * as)
  61. {
  62.     int i, rc;
  63.  
  64.     /* Identify ELF */
  65.     if (header->e_ident[EI_MAG0] != ELFMAG0 || header->e_ident[EI_MAG1] != ELFMAG1 ||
  66.         header->e_ident[EI_MAG2] != ELFMAG2 || header->e_ident[EI_MAG3] != ELFMAG3) {
  67.         return EE_INVALID;
  68.     }
  69.    
  70.     /* Identify ELF compatibility */
  71.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || header->e_machine != ELF_MACHINE ||
  72.         header->e_ident[EI_VERSION] != EV_CURRENT || header->e_version != EV_CURRENT ||
  73.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  74.         return EE_INCOMPATIBLE;
  75.     }
  76.  
  77.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  78.         return EE_INCOMPATIBLE;
  79.  
  80.     if (header->e_shentsize != sizeof(elf_section_header_t))
  81.         return EE_INCOMPATIBLE;
  82.  
  83.     /* Check if the object type is supported. */
  84.     if (header->e_type != ET_EXEC)
  85.         return EE_UNSUPPORTED;
  86.  
  87.     /* Walk through all segment headers and process them. */
  88.     for (i = 0; i < header->e_phnum; i++) {
  89.         rc = segment_header(&((elf_segment_header_t *)(((__u8 *) header) + header->e_phoff))[i], header, as);
  90.         if (rc != EE_OK)
  91.             return rc;
  92.     }
  93.  
  94.     /* Inspect all section headers and proccess them. */
  95.     for (i = 0; i < header->e_shnum; i++) {
  96.         rc = section_header(&((elf_section_header_t *)(((__u8 *) header) + header->e_shoff))[i], header, as);
  97.         if (rc != EE_OK)
  98.             return rc;
  99.     }
  100.  
  101.     return EE_OK;
  102. }
  103.  
  104. /** Print error message according to error code.
  105.  *
  106.  * @param rc Return code returned by elf_load().
  107.  *
  108.  * @return NULL terminated description of error.
  109.  */
  110. char *elf_error(int rc)
  111. {
  112.     ASSERT(rc < sizeof(error_codes)/sizeof(char *));
  113.  
  114.     return error_codes[rc];
  115. }
  116.  
  117. /** Process segment header.
  118.  *
  119.  * @param entry Segment header.
  120.  * @param elf ELF header.
  121.  * @param as Address space into wich the ELF is being loaded.
  122.  *
  123.  * @return EE_OK on success, error code otherwise.
  124.  */
  125. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  126. {
  127.     switch (entry->p_type) {
  128.         case PT_NULL:
  129.         case PT_PHDR:
  130.         break;
  131.         case PT_LOAD:
  132.         return load_segment(entry, elf, as);
  133.         break;
  134.         case PT_DYNAMIC:
  135.         case PT_INTERP:
  136.         case PT_SHLIB:
  137.         case PT_NOTE:
  138.         case PT_LOPROC:
  139.         case PT_HIPROC:
  140.         default:
  141.         return EE_UNSUPPORTED;
  142.         break;
  143.     }
  144.     return EE_OK;
  145. }
  146.  
  147. /** Load segment described by program header entry.
  148.  *
  149.  * @param entry Program header entry describing segment to be loaded.
  150.  * @param elf ELF header.
  151.  * @parma as Address space into wich the ELF is being loaded.
  152.  *
  153.  * @return EE_OK on success, error code otherwise.
  154.  */
  155. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  156. {
  157.     as_area_t *a;
  158.     int i, type = 0;
  159.     size_t segment_size;
  160.     __u8 *segment;
  161.  
  162.     if (entry->p_align > 1) {
  163.         if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
  164.             return EE_INVALID;
  165.         }
  166.     }
  167.  
  168.     /*
  169.      * Check if the segment doesn't interfere with kernel address space.
  170.      */
  171.     if (entry->p_vaddr + ALIGN_UP(entry->p_memsz, PAGE_SIZE) >= USER_ADDRESS_SPACE_END)
  172.         return EE_MEMORY;
  173.    
  174.     if (entry->p_flags & PF_X) {
  175.         type = AS_AREA_TEXT;
  176.     } else if (entry->p_flags & PF_W) {
  177.         type = AS_AREA_DATA;
  178.     } else {
  179.         return EE_UNSUPPORTED;
  180.     }
  181.  
  182.     /*
  183.      * Check if the virtual address starts on page boundary.
  184.      */
  185.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
  186.         return EE_UNSUPPORTED;
  187.  
  188.     /*
  189.      * Copying the segment out is certainly necessary for segments with p_filesz < p_memsz
  190.      * because of the effect of .bss-like sections. For security reasons, it looks like a
  191.      * good idea to copy the segment anyway.
  192.      */
  193.     segment_size = ALIGN_UP(max(entry->p_filesz, entry->p_memsz), PAGE_SIZE);
  194.     segment = malloc(segment_size, 0);
  195.     if (entry->p_filesz < entry->p_memsz)
  196.         memsetb((__address) (segment + entry->p_filesz), segment_size - entry->p_filesz, 0);
  197.     memcpy(segment, (void *) (((__address) elf) + entry->p_offset), entry->p_filesz);
  198.  
  199.     a = as_area_create(as, AS_AREA_TEXT, SIZE2FRAMES(entry->p_memsz), entry->p_vaddr);
  200.     if (!a)
  201.         return EE_IRRECOVERABLE;
  202.    
  203.     for (i = 0; i < SIZE2FRAMES(entry->p_filesz); i++) {
  204.         as_set_mapping(as, entry->p_vaddr + i*PAGE_SIZE, KA2PA(((__address) segment) + i*PAGE_SIZE));
  205.     }
  206.    
  207.     return EE_OK;
  208. }
  209.  
  210. /** Process section header.
  211.  *
  212.  * @param entry Segment header.
  213.  * @param elf ELF header.
  214.  * @param as Address space into wich the ELF is being loaded.
  215.  *
  216.  * @return EE_OK on success, error code otherwise.
  217.  */
  218. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as)
  219. {
  220.     switch (entry->sh_type) {
  221.         default:
  222.         break;
  223.     }
  224.    
  225.     return EE_OK;
  226. }
  227.