security/integrity/ima/ima_init.c

   1 /*
   2  * Copyright (C) 2005,2006,2007,2008 IBM Corporation
   3  *
   4  * Authors:
   5  * Reiner Sailer      <sailer@watson.ibm.com>
   6  * Leendert van Doorn <leendert@watson.ibm.com>
   7  * Mimi Zohar         <zohar@us.ibm.com>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation, version 2 of the
  12  * License.
  13  *
  14  * File: ima_init.c
  15  *             initialization and cleanup functions
  16  */
  17 #include <linux/module.h>
  18 #include <linux/scatterlist.h>
  19 #include <linux/slab.h>
  20 #include <linux/err.h>
  21 #include "ima.h"
  22
  23 /* name for boot aggregate entry */
  24 static const char *boot_aggregate_name = "boot_aggregate";
  25 int ima_used_chip;
  26
  27 /* Add the boot aggregate to the IMA measurement list and extend
  28  * the PCR register.
  29  *
  30  * Calculate the boot aggregate, a SHA1 over tpm registers 0-7,
  31  * assuming a TPM chip exists, and zeroes if the TPM chip does not
  32  * exist.  Add the boot aggregate measurement to the measurement
  33  * list and extend the PCR register.
  34  *
  35  * If a tpm chip does not exist, indicate the core root of trust is
  36  * not hardware based by invalidating the aggregate PCR value.
  37  * (The aggregate PCR value is invalidated by adding one value to
  38  * the measurement list and extending the aggregate PCR value with
  39  * a different value.) Violations add a zero entry to the measurement
  40  * list and extend the aggregate PCR value with ff...ff's.
  41  */
  42 static void __init ima_add_boot_aggregate(void)
  43 {
  44         struct ima_template_entry *entry;
  45         const char *op = "add_boot_aggregate";
  46         const char *audit_cause = "ENOMEM";
  47         int result = -ENOMEM;
  48         int violation = 1;
  49
  50         entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  51         if (!entry)
  52                 goto err_out;
  53
  54         memset(&entry->template, 0, sizeof(entry->template));
  55         strncpy(entry->template.file_name, boot_aggregate_name,
  56                 IMA_EVENT_NAME_LEN_MAX);
  57         if (ima_used_chip) {
  58                 violation = 0;
  59                 result = ima_calc_boot_aggregate(entry->template.digest);
  60                 if (result < 0) {
  61                         audit_cause = "hashing_error";
  62                         kfree(entry);
  63                         goto err_out;
  64                 }
  65         }
  66         result = ima_store_template(entry, violation, NULL);
  67         if (result < 0)
  68                 kfree(entry);
  69         return;
  70 err_out:
  71         integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,
  72                             audit_cause, result, 0);
  73 }
  74
  75 int __init ima_init(void)
  76 {
  77         u8 pcr_i[IMA_DIGEST_SIZE];
  78         int rc;
  79
  80         ima_used_chip = 0;
  81         rc = tpm_pcr_read(TPM_ANY_NUM, 0, pcr_i);
  82         if (rc == 0)
  83                 ima_used_chip = 1;
  84
  85         if (!ima_used_chip)
  86                 pr_info("IMA: No TPM chip found, activating TPM-bypass!\n");
  87
  88         ima_add_boot_aggregate();       /* boot aggregate must be first entry */
  89         ima_init_policy();
  90
  91         return ima_fs_init();
  92 }
  93
  94 void __exit ima_cleanup(void)
  95 {
  96         ima_fs_cleanup();
  97 }