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[];
  23
  24/*
  25 * We need to make sure ccache doesn't cache the .o file as it doesn't notice
  26 * if modsign.pub changes.
  27 */
  28static __initdata const char annoy_ccache[] = __TIME__ "foo";
  29
  30/*
  31 * Load the compiled-in keys
  32 */
  33static __init int module_verify_init(void)
  34{
  35        pr_notice("Initialise module verification\n");
  36
  37        modsign_keyring = keyring_alloc(".module_sign",
  38                                        KUIDT_INIT(0), KGIDT_INIT(0),
  39                                        current_cred(),
  40                                        ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
  41                                         KEY_USR_VIEW | KEY_USR_READ),
  42                                        KEY_ALLOC_NOT_IN_QUOTA, NULL);
  43        if (IS_ERR(modsign_keyring))
  44                panic("Can't allocate module signing keyring\n");
  45
  46        return 0;
  47}
  48
  49/*
  50 * Must be initialised before we try and load the keys into the keyring.
  51 */
  52device_initcall(module_verify_init);
  53
  54/*
  55 * Load the compiled-in keys
  56 */
  57static __init int load_module_signing_keys(void)
  58{
  59        key_ref_t key;
  60        const u8 *p, *end;
  61        size_t plen;
  62
  63        pr_notice("Loading module verification certificates\n");
  64
  65        end = modsign_certificate_list_end;
  66        p = modsign_certificate_list;
  67        while (p < end) {
  68                /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
  69                 * than 256 bytes in size.
  70                 */
  71                if (end - p < 4)
  72                        goto dodgy_cert;
  73                if (p[0] != 0x30 &&
  74                    p[1] != 0x82)
  75                        goto dodgy_cert;
  76                plen = (p[2] << 8) | p[3];
  77                plen += 4;
  78                if (plen > end - p)
  79                        goto dodgy_cert;
  80
  81                key = key_create_or_update(make_key_ref(modsign_keyring, 1),
  82                                           "asymmetric",
  83                                           NULL,
  84                                           p,
  85                                           plen,
  86                                           (KEY_POS_ALL & ~KEY_POS_SETATTR) |
  87                                           KEY_USR_VIEW,
  88                                           KEY_ALLOC_NOT_IN_QUOTA);
  89                if (IS_ERR(key))
  90                        pr_err("MODSIGN: Problem loading in-kernel X.509 certificate (%ld)\n",
  91                               PTR_ERR(key));
  92                else
  93                        pr_notice("MODSIGN: Loaded cert '%s'\n",
  94                                  key_ref_to_ptr(key)->description);
  95                p += plen;
  96        }
  97
  98        return 0;
  99
 100dodgy_cert:
 101        pr_err("MODSIGN: Problem parsing in-kernel X.509 certificate list\n");
 102        return 0;
 103}
 104late_initcall(load_module_signing_keys);
 105
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