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