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
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/module.h>
  21 #include <linux/scatterlist.h>
  22 #include <linux/slab.h>
  23 #include <linux/err.h>
  24 #include <crypto/hash_info.h>
  25 #include "ima.h"
  26
  27 /* name for boot aggregate entry */
  28 static const char *boot_aggregate_name = "boot_aggregate";
  29 int ima_used_chip;
  30
  31 /* Add the boot aggregate to the IMA measurement list and extend
  32  * the PCR register.
  33  *
  34  * Calculate the boot aggregate, a SHA1 over tpm registers 0-7,
  35  * assuming a TPM chip exists, and zeroes if the TPM chip does not
  36  * exist.  Add the boot aggregate measurement to the measurement
  37  * list and extend the PCR register.
  38  *
  39  * If a tpm chip does not exist, indicate the core root of trust is
  40  * not hardware based by invalidating the aggregate PCR value.
  41  * (The aggregate PCR value is invalidated by adding one value to
  42  * the measurement list and extending the aggregate PCR value with
  43  * a different value.) Violations add a zero entry to the measurement
  44  * list and extend the aggregate PCR value with ff...ff's.
  45  */
  46 static void __init ima_add_boot_aggregate(void)
  47 {
  48         static const char op[] = "add_boot_aggregate";
  49         const char *audit_cause = "ENOMEM";
  50         struct ima_template_entry *entry;
  51         struct integrity_iint_cache tmp_iint, *iint = &tmp_iint;
  52         int result = -ENOMEM;
  53         int violation = 0;
  54         struct {
  55                 struct ima_digest_data hdr;
  56                 char digest[TPM_DIGEST_SIZE];
  57         } hash;
  58
  59         memset(iint, 0, sizeof(*iint));
  60         memset(&hash, 0, sizeof(hash));
  61         iint->ima_hash = &hash.hdr;
  62         iint->ima_hash->algo = HASH_ALGO_SHA1;
  63         iint->ima_hash->length = SHA1_DIGEST_SIZE;
  64
  65         if (ima_used_chip) {
  66                 result = ima_calc_boot_aggregate(&hash.hdr);
  67                 if (result < 0) {
  68                         audit_cause = "hashing_error";
  69                         goto err_out;
  70                 }
  71         }
  72
  73         result = ima_alloc_init_template(iint, NULL, boot_aggregate_name,
  74                                          NULL, 0, &entry);
  75         if (result < 0)
  76                 return;
  77
  78         result = ima_store_template(entry, violation, NULL,
  79                                     boot_aggregate_name);
  80         if (result < 0)
  81                 ima_free_template_entry(entry);
  82         return;
  83 err_out:
  84         integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,
  85                             audit_cause, result, 0);
  86 }
  87
  88 int __init ima_init(void)
  89 {
  90         u8 pcr_i[TPM_DIGEST_SIZE];
  91         int rc;
  92
  93         ima_used_chip = 0;
  94         rc = tpm_pcr_read(TPM_ANY_NUM, 0, pcr_i);
  95         if (rc == 0)
  96                 ima_used_chip = 1;
  97
  98         if (!ima_used_chip)
  99                 pr_info("No TPM chip found, activating TPM-bypass!\n");
 100
 101         rc = ima_init_crypto();
 102         if (rc)
 103                 return rc;
 104         rc = ima_init_template();
 105         if (rc != 0)
 106                 return rc;
 107
 108         ima_add_boot_aggregate();       /* boot aggregate must be first entry */
 109         ima_init_policy();
 110
 111         return ima_fs_init();
 112 }