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 asm(".section .init.data,\"aw\"\n"
  24     "modsign_certificate_list:\n"
  25     ".incbin \"signing_key.x509\"\n"
  26     ".incbin \"extra_certificates\"\n"
  27     "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  */
  34 static __initdata const char annoy_ccache[] = __TIME__ "foo";
  35
  36 /*
  37  * Load the compiled-in keys
  38  */
  39 static __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  */
  61 device_initcall(module_verify_init);
  62
  63 /*
  64  * Load the compiled-in keys
  65  */
  66 static __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
 109 dodgy_cert:
 110         pr_err("MODSIGN: Problem parsing in-kernel X.509 certificate list\n");
 111         return 0;
 112 }
 113 late_initcall(load_module_signing_keys);