arch/powerpc/kernel/ima_arch.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2019 IBM Corporation
   4  * Author: Nayna Jain
   5  */
   6
   7 #include <linux/ima.h>
   8 #include <asm/secure_boot.h>
   9
  10 bool arch_ima_get_secureboot(void)
  11 {
  12         return is_ppc_secureboot_enabled();
  13 }
  14
  15 /*
  16  * The "secure_rules" are enabled only on "secureboot" enabled systems.
  17  * These rules verify the file signatures against known good values.
  18  * The "appraise_type=imasig|modsig" option allows the known good signature
  19  * to be stored as an xattr or as an appended signature.
  20  *
  21  * To avoid duplicate signature verification as much as possible, the IMA
  22  * policy rule for module appraisal is added only if CONFIG_MODULE_SIG_FORCE
  23  * is not enabled.
  24  */
  25 static const char *const secure_rules[] = {
  26         "appraise func=KEXEC_KERNEL_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
  27 #ifndef CONFIG_MODULE_SIG_FORCE
  28         "appraise func=MODULE_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
  29 #endif
  30         NULL
  31 };
  32
  33 /*
  34  * The "trusted_rules" are enabled only on "trustedboot" enabled systems.
  35  * These rules add the kexec kernel image and kernel modules file hashes to
  36  * the IMA measurement list.
  37  */
  38 static const char *const trusted_rules[] = {
  39         "measure func=KEXEC_KERNEL_CHECK",
  40         "measure func=MODULE_CHECK",
  41         NULL
  42 };
  43
  44 /*
  45  * The "secure_and_trusted_rules" contains rules for both the secure boot and
  46  * trusted boot. The "template=ima-modsig" option includes the appended
  47  * signature, when available, in the IMA measurement list.
  48  */
  49 static const char *const secure_and_trusted_rules[] = {
  50         "measure func=KEXEC_KERNEL_CHECK template=ima-modsig",
  51         "measure func=MODULE_CHECK template=ima-modsig",
  52         "appraise func=KEXEC_KERNEL_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
  53 #ifndef CONFIG_MODULE_SIG_FORCE
  54         "appraise func=MODULE_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
  55 #endif
  56         NULL
  57 };
  58
  59 /*
  60  * Returns the relevant IMA arch-specific policies based on the system secure
  61  * boot state.
  62  */
  63 const char *const *arch_get_ima_policy(void)
  64 {
  65         if (is_ppc_secureboot_enabled()) {
  66                 if (IS_ENABLED(CONFIG_MODULE_SIG))
  67                         set_module_sig_enforced();
  68
  69                 if (is_ppc_trustedboot_enabled())
  70                         return secure_and_trusted_rules;
  71                 else
  72                         return secure_rules;
  73         } else if (is_ppc_trustedboot_enabled()) {
  74                 return trusted_rules;
  75         }
  76
  77         return NULL;
  78 }