linux/kernel/modsign_pubkey.c
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   1/* Public keys for module signature verification
   2 *
   3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11
  12#include <linux/kernel.h>
  13#include <linux/sched.h>
  14#include <linux/cred.h>
  15#include <linux/err.h>
  16#include <keys/asymmetric-type.h>
  17#include "module-internal.h"
  18
  19struct key *modsign_keyring;
  20
  21extern __initdata const u8 modsign_certificate_list[];
  22extern __initdata const u8 modsign_certificate_list_end[];
  23asm(".section .init.data,\"aw\"\n"
  24    SYMBOL_PREFIX "modsign_certificate_list:\n"
  25    ".incbin \"signing_key.x509\"\n"
  26    ".incbin \"extra_certificates\"\n"
  27    SYMBOL_PREFIX "modsign_certificate_list_end:"
  28    );
  29
  30/*
  31 * We need to make sure ccache doesn't cache the .o file as it doesn't notice
  32 * if modsign.pub changes.
  33 */
  34static __initdata const char annoy_ccache[] = __TIME__ "foo";
  35
  36/*
  37 * Load the compiled-in keys
  38 */
  39static __init int module_verify_init(void)
  40{
  41        pr_notice("Initialise module verification\n");
  42
  43        modsign_keyring = key_alloc(&key_type_keyring, ".module_sign",
  44                                    KUIDT_INIT(0), KGIDT_INIT(0),
  45                                    current_cred(),
  46                                    (KEY_POS_ALL & ~KEY_POS_SETATTR) |
  47                                    KEY_USR_VIEW | KEY_USR_READ,
  48                                    KEY_ALLOC_NOT_IN_QUOTA);
  49        if (IS_ERR(modsign_keyring))
  50                panic("Can't allocate module signing keyring\n");
  51
  52        if (key_instantiate_and_link(modsign_keyring, NULL, 0, NULL, NULL) < 0)
  53                panic("Can't instantiate module signing keyring\n");
  54
  55        return 0;
  56}
  57
  58/*
  59 * Must be initialised before we try and load the keys into the keyring.
  60 */
  61device_initcall(module_verify_init);
  62
  63/*
  64 * Load the compiled-in keys
  65 */
  66static __init int load_module_signing_keys(void)
  67{
  68        key_ref_t key;
  69        const u8 *p, *end;
  70        size_t plen;
  71
  72        pr_notice("Loading module verification certificates\n");
  73
  74        end = modsign_certificate_list_end;
  75        p = modsign_certificate_list;
  76        while (p < end) {
  77                /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
  78                 * than 256 bytes in size.
  79                 */
  80                if (end - p < 4)
  81                        goto dodgy_cert;
  82                if (p[0] != 0x30 &&
  83                    p[1] != 0x82)
  84                        goto dodgy_cert;
  85                plen = (p[2] << 8) | p[3];
  86                plen += 4;
  87                if (plen > end - p)
  88                        goto dodgy_cert;
  89
  90                key = key_create_or_update(make_key_ref(modsign_keyring, 1),
  91                                           "asymmetric",
  92                                           NULL,
  93                                           p,
  94                                           plen,
  95                                           (KEY_POS_ALL & ~KEY_POS_SETATTR) |
  96                                           KEY_USR_VIEW,
  97                                           KEY_ALLOC_NOT_IN_QUOTA);
  98                if (IS_ERR(key))
  99                        pr_err("MODSIGN: Problem loading in-kernel X.509 certificate (%ld)\n",
 100                               PTR_ERR(key));
 101                else
 102                        pr_notice("MODSIGN: Loaded cert '%s'\n",
 103                                  key_ref_to_ptr(key)->description);
 104                p += plen;
 105        }
 106
 107        return 0;
 108
 109dodgy_cert:
 110        pr_err("MODSIGN: Problem parsing in-kernel X.509 certificate list\n");
 111        return 0;
 112}
 113late_initcall(load_module_signing_keys);
 114
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