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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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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 */
#ifdef CONFIG_IMA_KEXEC
static unsigned long binary_runtime_size;
#else
static unsigned long binary_runtime_size = ULONG_MAX;
#endif
/* 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,
int pcr)
{
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) && (qe->entry->pcr == pcr)) {
ret = qe;
break;
}
}
rcu_read_unlock();
return ret;
}
/*
* Calculate the memory required for serializing a single
* binary_runtime_measurement list entry, which contains a
* couple of variable length fields (e.g template name and data).
*/
static int get_binary_runtime_size(struct ima_template_entry *entry)
{
int size = 0;
size += sizeof(u32); /* pcr */
size += sizeof(entry->digest);
size += sizeof(int); /* template name size field */
size += strlen(entry->template_desc->name);
size += sizeof(entry->template_data_len);
size += entry->template_data_len;
return size;
}
/* ima_add_template_entry helper function:
* - Add template entry to the measurement list and hash table, for
* all entries except those carried across kexec.
*
* (Called with ima_extend_list_mutex held.)
*/
static int ima_add_digest_entry(struct ima_template_entry *entry,
bool update_htable)
{
struct ima_queue_entry *qe;
unsigned int key;
qe = kmalloc(sizeof(*qe), GFP_KERNEL);
if (qe == NULL) {
pr_err("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);
if (update_htable) {
key = ima_hash_key(entry->digest);
hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
}
if (binary_runtime_size != ULONG_MAX) {
int size;
size = get_binary_runtime_size(entry);
binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
binary_runtime_size + size : ULONG_MAX;
}
return 0;
}
/*
* Return the amount of memory required for serializing the
* entire binary_runtime_measurement list, including the ima_kexec_hdr
* structure.
*/
unsigned long ima_get_binary_runtime_size(void)
{
if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
return ULONG_MAX;
else
return binary_runtime_size + sizeof(struct ima_kexec_hdr);
};
static int ima_pcr_extend(const u8 *hash, int pcr)
{
int result = 0;
if (!ima_used_chip)
return result;
result = tpm_pcr_extend(NULL, pcr, hash);
if (result != 0)
pr_err("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.
*
* On systems which support carrying the IMA measurement list across
* kexec, maintain the total memory size required for serializing the
* binary_runtime_measurements.
*/
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, entry->pcr)) {
audit_cause = "hash_exists";
result = -EEXIST;
goto out;
}
}
result = ima_add_digest_entry(entry, 1);
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, entry->pcr);
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;
}
int ima_restore_measurement_entry(struct ima_template_entry *entry)
{
int result = 0;
mutex_lock(&ima_extend_list_mutex);
result = ima_add_digest_entry(entry, 0);
mutex_unlock(&ima_extend_list_mutex);
return result;
}
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