ima_init.c

Go to the documentation of this file.

/*
 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
 *
 * Authors:
 * Reiner Sailer      <[email protected]>
 * Leendert van Doorn <[email protected]>
 * Mimi Zohar         <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 * File: ima_init.c
 *             initialization and cleanup functions
 */
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/err.h>
#include "ima.h"

/* name for boot aggregate entry */
static const char *boot_aggregate_name = "boot_aggregate";
int ima_used_chip;

/* Add the boot aggregate to the IMA measurement list and extend
 * the PCR register.
 *
 * Calculate the boot aggregate, a SHA1 over tpm registers 0-7,
 * assuming a TPM chip exists, and zeroes if the TPM chip does not
 * exist.  Add the boot aggregate measurement to the measurement
 * list and extend the PCR register.
 *
 * If a tpm chip does not exist, indicate the core root of trust is
 * not hardware based by invalidating the aggregate PCR value.
 * (The aggregate PCR value is invalidated by adding one value to
 * the measurement list and extending the aggregate PCR value with
 * a different value.) Violations add a zero entry to the measurement
 * list and extend the aggregate PCR value with ff...ff's.
 */
static void __init ima_add_boot_aggregate(void)
{
    struct ima_template_entry *entry;
    const char *op = "add_boot_aggregate";
    const char *audit_cause = "ENOMEM";
    int result = -ENOMEM;
    int violation = 1;

    entry = kmalloc(sizeof(*entry), GFP_KERNEL);
    if (!entry)
        goto err_out;

    memset(&entry->template, 0, sizeof(entry->template));
    strncpy(entry->template.file_name, boot_aggregate_name,
        IMA_EVENT_NAME_LEN_MAX);
    if (ima_used_chip) {
        violation = 0;
        result = ima_calc_boot_aggregate(entry->template.digest);
        if (result < 0) {
            audit_cause = "hashing_error";
            kfree(entry);
            goto err_out;
        }
    }
    result = ima_store_template(entry, violation, NULL);
    if (result < 0)
        kfree(entry);
    return;
err_out:
    integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, boot_aggregate_name, op,
                audit_cause, result, 0);
}

int __init ima_init(void)
{
    u8 pcr_i[IMA_DIGEST_SIZE];
    int rc;

    ima_used_chip = 0;
    rc = tpm_pcr_read(TPM_ANY_NUM, 0, pcr_i);
    if (rc == 0)
        ima_used_chip = 1;

    if (!ima_used_chip)
        pr_info("IMA: No TPM chip found, activating TPM-bypass!\n");

    ima_add_boot_aggregate();   /* boot aggregate must be first entry */
    ima_init_policy();

    return ima_fs_init();
}