kernel/modsign_pubkey.c

   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
  19 struct key *modsign_keyring;
  20
  21 extern __initdata const u8 modsign_certificate_list[];
  22 extern __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  */
  28 static __initdata const char annoy_ccache[] = __TIME__ "foo";
  29
  30 /*
  31  * Load the compiled-in keys
  32  */
  33 static __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  */
  52 device_initcall(module_verify_init);
  53
  54 /*
  55  * Load the compiled-in keys
  56  */
  57 static __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
 100 dodgy_cert:
 101         pr_err("MODSIGN: Problem parsing in-kernel X.509 certificate list\n");
 102         return 0;
 103 }
 104 late_initcall(load_module_signing_keys);