/security/integrity/ima/ima_queue.c

  1/*
  2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
  3 *
  4 * Authors:
  5 * Serge Hallyn <serue@us.ibm.com>
  6 * Reiner Sailer <sailer@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_queue.c
 15 *       Implements queues that store template measurements and
 16 *       maintains aggregate over the stored measurements
 17 *       in the pre-configured TPM PCR (if available).
 18 *       The measurement list is append-only. No entry is
 19 *       ever removed or changed during the boot-cycle.
 20 */
 21#include <linux/module.h>
 22#include <linux/rculist.h>
 23#include <linux/slab.h>
 24#include "ima.h"
 25
 26LIST_HEAD(ima_measurements);	/* list of all measurements */
 27
 28/* key: inode (before secure-hashing a file) */
 29struct ima_h_table ima_htable = {
 30	.len = ATOMIC_LONG_INIT(0),
 31	.violations = ATOMIC_LONG_INIT(0),
 32	.queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
 33};
 34
 35/* mutex protects atomicity of extending measurement list
 36 * and extending the TPM PCR aggregate. Since tpm_extend can take
 37 * long (and the tpm driver uses a mutex), we can't use the spinlock.
 38 */
 39static DEFINE_MUTEX(ima_extend_list_mutex);
 40
 41/* lookup up the digest value in the hash table, and return the entry */
 42static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
 43{
 44	struct ima_queue_entry *qe, *ret = NULL;
 45	unsigned int key;
 46	struct hlist_node *pos;
 47	int rc;
 48
 49	key = ima_hash_key(digest_value);
 50	rcu_read_lock();
 51	hlist_for_each_entry_rcu(qe, pos, &ima_htable.queue[key], hnext) {
 52		rc = memcmp(qe->entry->digest, digest_value, IMA_DIGEST_SIZE);
 53		if (rc == 0) {
 54			ret = qe;
 55			break;
 56		}
 57	}
 58	rcu_read_unlock();
 59	return ret;
 60}
 61
 62/* ima_add_template_entry helper function:
 63 * - Add template entry to measurement list and hash table.
 64 *
 65 * (Called with ima_extend_list_mutex held.)
 66 */
 67static int ima_add_digest_entry(struct ima_template_entry *entry)
 68{
 69	struct ima_queue_entry *qe;
 70	unsigned int key;
 71
 72	qe = kmalloc(sizeof(*qe), GFP_KERNEL);
 73	if (qe == NULL) {
 74		pr_err("OUT OF MEMORY ERROR creating queue entry.\n");
 75		return -ENOMEM;
 76	}
 77	qe->entry = entry;
 78
 79	INIT_LIST_HEAD(&qe->later);
 80	list_add_tail_rcu(&qe->later, &ima_measurements);
 81
 82	atomic_long_inc(&ima_htable.len);
 83	key = ima_hash_key(entry->digest);
 84	hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
 85	return 0;
 86}
 87
 88static int ima_pcr_extend(const u8 *hash)
 89{
 90	int result = 0;
 91
 92	if (!ima_used_chip)
 93		return result;
 94
 95	result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
 96	if (result != 0)
 97		pr_err("Error Communicating to TPM chip\n");
 98	return result;
 99}
100
101/* Add template entry to the measurement list and hash table,
102 * and extend the pcr.
103 */
104int ima_add_template_entry(struct ima_template_entry *entry, int violation,
105			   const char *op, struct inode *inode)
106{
107	u8 digest[IMA_DIGEST_SIZE];
108	const char *audit_cause = "hash_added";
109	int audit_info = 1;
110	int result = 0;
111
112	mutex_lock(&ima_extend_list_mutex);
113	if (!violation) {
114		memcpy(digest, entry->digest, sizeof digest);
115		if (ima_lookup_digest_entry(digest)) {
116			audit_cause = "hash_exists";
117			goto out;
118		}
119	}
120
121	result = ima_add_digest_entry(entry);
122	if (result < 0) {
123		audit_cause = "ENOMEM";
124		audit_info = 0;
125		goto out;
126	}
127
128	if (violation)		/* invalidate pcr */
129		memset(digest, 0xff, sizeof digest);
130
131	result = ima_pcr_extend(digest);
132	if (result != 0) {
133		audit_cause = "TPM error";
134		audit_info = 0;
135	}
136out:
137	mutex_unlock(&ima_extend_list_mutex);
138	integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
139			    entry->template.file_name,
140			    op, audit_cause, result, audit_info);
141	return result;
142}