kernel/module/livepatch.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Module livepatch support
   4  *
   5  * Copyright (C) 2016 Jessica Yu <jeyu@redhat.com>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/string.h>
  10 #include <linux/slab.h>
  11 #include "internal.h"
  12
  13 /*
  14  * Persist ELF information about a module. Copy the ELF header,
  15  * section header table, section string table, and symtab section
  16  * index from info to mod->klp_info.
  17  */
  18 int copy_module_elf(struct module *mod, struct load_info *info)
  19 {
  20         unsigned int size, symndx;
  21         int ret;
  22
  23         size = sizeof(*mod->klp_info);
  24         mod->klp_info = kmalloc(size, GFP_KERNEL);
  25         if (!mod->klp_info)
  26                 return -ENOMEM;
  27
  28         /* ELF header */
  29         size = sizeof(mod->klp_info->hdr);
  30         memcpy(&mod->klp_info->hdr, info->hdr, size);
  31
  32         /* ELF section header table */
  33         size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
  34         mod->klp_info->sechdrs = kmemdup(info->sechdrs, size, GFP_KERNEL);
  35         if (!mod->klp_info->sechdrs) {
  36                 ret = -ENOMEM;
  37                 goto free_info;
  38         }
  39
  40         /* ELF section name string table */
  41         size = info->sechdrs[info->hdr->e_shstrndx].sh_size;
  42         mod->klp_info->secstrings = kmemdup(info->secstrings, size, GFP_KERNEL);
  43         if (!mod->klp_info->secstrings) {
  44                 ret = -ENOMEM;
  45                 goto free_sechdrs;
  46         }
  47
  48         /* ELF symbol section index */
  49         symndx = info->index.sym;
  50         mod->klp_info->symndx = symndx;
  51
  52         /*
  53          * For livepatch modules, core_kallsyms.symtab is a complete
  54          * copy of the original symbol table. Adjust sh_addr to point
  55          * to core_kallsyms.symtab since the copy of the symtab in module
  56          * init memory is freed at the end of do_init_module().
  57          */
  58         mod->klp_info->sechdrs[symndx].sh_addr = (unsigned long)mod->core_kallsyms.symtab;
  59
  60         return 0;
  61
  62 free_sechdrs:
  63         kfree(mod->klp_info->sechdrs);
  64 free_info:
  65         kfree(mod->klp_info);
  66         return ret;
  67 }
  68
  69 void free_module_elf(struct module *mod)
  70 {
  71         kfree(mod->klp_info->sechdrs);
  72         kfree(mod->klp_info->secstrings);
  73         kfree(mod->klp_info);
  74 }