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/*
* Copyright (C) 2005,2006,2007,2008 IBM Corporation
*
* Authors:
* Serge Hallyn <serue@us.ibm.com>
* Reiner Sailer <sailer@watson.ibm.com>
* Mimi Zohar <zohar@us.ibm.com>
*
* 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_queue.c
* Implements queues that store template measurements and
* maintains aggregate over the stored measurements
* in the pre-configured TPM PCR (if available).
* The measurement list is append-only. No entry is
* ever removed or changed during the boot-cycle.
*/
#include <linux/module.h>
#include <linux/rculist.h>
#include <linux/slab.h>
#include "ima.h"
#define AUDIT_CAUSE_LEN_MAX 32
LIST_HEAD(ima_measurements); /* list of all measurements */
/* key: inode (before secure-hashing a file) */
struct ima_h_table ima_htable = {
.len = ATOMIC_LONG_INIT(0),
.violations = ATOMIC_LONG_INIT(0),
.queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
};
/* mutex protects atomicity of extending measurement list
* and extending the TPM PCR aggregate. Since tpm_extend can take
* long (and the tpm driver uses a mutex), we can't use the spinlock.
*/
static DEFINE_MUTEX(ima_extend_list_mutex);
/* lookup up the digest value in the hash table, and return the entry */
static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
{
struct ima_queue_entry *qe, *ret = NULL;
unsigned int key;
int rc;
key = ima_hash_key(digest_value);
rcu_read_lock();
hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE);
if (rc == 0) {
ret = qe;
break;
}
}
rcu_read_unlock();
return ret;
}
/* ima_add_template_entry helper function:
* - Add template entry to measurement list and hash table.
*
* (Called with ima_extend_list_mutex held.)
*/
static int ima_add_digest_entry(struct ima_template_entry *entry)
{
struct ima_queue_entry *qe;
unsigned int key;
qe = kmalloc(sizeof(*qe), GFP_KERNEL);
if (qe == NULL) {
pr_err("IMA: OUT OF MEMORY ERROR creating queue entry.\n");
return -ENOMEM;
}
qe->entry = entry;
INIT_LIST_HEAD(&qe->later);
list_add_tail_rcu(&qe->later, &ima_measurements);
atomic_long_inc(&ima_htable.len);
key = ima_hash_key(entry->digest);
hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
return 0;
}
static int ima_pcr_extend(const u8 *hash)
{
int result = 0;
if (!ima_used_chip)
return result;
result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
if (result != 0)
pr_err("IMA: Error Communicating to TPM chip, result: %d\n",
result);
return result;
}
/* Add template entry to the measurement list and hash table,
* and extend the pcr.
*/
int ima_add_template_entry(struct ima_template_entry *entry, int violation,
const char *op, struct inode *inode,
const unsigned char *filename)
{
u8 digest[TPM_DIGEST_SIZE];
const char *audit_cause = "hash_added";
char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
int audit_info = 1;
int result = 0, tpmresult = 0;
mutex_lock(&ima_extend_list_mutex);
if (!violation) {
memcpy(digest, entry->digest, sizeof digest);
if (ima_lookup_digest_entry(digest)) {
audit_cause = "hash_exists";
result = -EEXIST;
goto out;
}
}
result = ima_add_digest_entry(entry);
if (result < 0) {
audit_cause = "ENOMEM";
audit_info = 0;
goto out;
}
if (violation) /* invalidate pcr */
memset(digest, 0xff, sizeof digest);
tpmresult = ima_pcr_extend(digest);
if (tpmresult != 0) {
snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
tpmresult);
audit_cause = tpm_audit_cause;
audit_info = 0;
}
out:
mutex_unlock(&ima_extend_list_mutex);
integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
op, audit_cause, result, audit_info);
return result;
}
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