150 lines
3.9 KiB
C
150 lines
3.9 KiB
C
/*
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* Copyright (C) 2005,2006,2007,2008 IBM Corporation
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*
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* Authors:
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* Serge Hallyn <serue@us.ibm.com>
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* Reiner Sailer <sailer@watson.ibm.com>
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* Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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* File: ima_queue.c
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* Implements queues that store template measurements and
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* maintains aggregate over the stored measurements
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* in the pre-configured TPM PCR (if available).
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* The measurement list is append-only. No entry is
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* ever removed or changed during the boot-cycle.
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*/
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#include <linux/module.h>
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#include <linux/rculist.h>
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#include <linux/slab.h>
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#include "ima.h"
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#define AUDIT_CAUSE_LEN_MAX 32
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LIST_HEAD(ima_measurements); /* list of all measurements */
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/* key: inode (before secure-hashing a file) */
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struct ima_h_table ima_htable = {
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.len = ATOMIC_LONG_INIT(0),
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.violations = ATOMIC_LONG_INIT(0),
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.queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
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};
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/* mutex protects atomicity of extending measurement list
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* and extending the TPM PCR aggregate. Since tpm_extend can take
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* long (and the tpm driver uses a mutex), we can't use the spinlock.
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*/
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static DEFINE_MUTEX(ima_extend_list_mutex);
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/* lookup up the digest value in the hash table, and return the entry */
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static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
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{
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struct ima_queue_entry *qe, *ret = NULL;
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unsigned int key;
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struct hlist_node *pos;
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int rc;
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key = ima_hash_key(digest_value);
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rcu_read_lock();
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hlist_for_each_entry_rcu(qe, pos, &ima_htable.queue[key], hnext) {
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rc = memcmp(qe->entry->digest, digest_value, IMA_DIGEST_SIZE);
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if (rc == 0) {
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ret = qe;
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break;
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}
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}
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rcu_read_unlock();
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return ret;
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}
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/* ima_add_template_entry helper function:
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* - Add template entry to measurement list and hash table.
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*
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* (Called with ima_extend_list_mutex held.)
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*/
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static int ima_add_digest_entry(struct ima_template_entry *entry)
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{
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struct ima_queue_entry *qe;
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unsigned int key;
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qe = kmalloc(sizeof(*qe), GFP_KERNEL);
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if (qe == NULL) {
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pr_err("IMA: OUT OF MEMORY ERROR creating queue entry.\n");
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return -ENOMEM;
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}
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qe->entry = entry;
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INIT_LIST_HEAD(&qe->later);
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list_add_tail_rcu(&qe->later, &ima_measurements);
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atomic_long_inc(&ima_htable.len);
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key = ima_hash_key(entry->digest);
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hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
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return 0;
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}
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static int ima_pcr_extend(const u8 *hash)
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{
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int result = 0;
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if (!ima_used_chip)
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return result;
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result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
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if (result != 0)
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pr_err("IMA: Error Communicating to TPM chip, result: %d\n",
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result);
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return result;
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}
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/* Add template entry to the measurement list and hash table,
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* and extend the pcr.
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*/
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int ima_add_template_entry(struct ima_template_entry *entry, int violation,
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const char *op, struct inode *inode)
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{
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u8 digest[IMA_DIGEST_SIZE];
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const char *audit_cause = "hash_added";
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char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
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int audit_info = 1;
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int result = 0, tpmresult = 0;
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mutex_lock(&ima_extend_list_mutex);
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if (!violation) {
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memcpy(digest, entry->digest, sizeof digest);
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if (ima_lookup_digest_entry(digest)) {
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audit_cause = "hash_exists";
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result = -EEXIST;
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goto out;
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}
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}
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result = ima_add_digest_entry(entry);
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if (result < 0) {
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audit_cause = "ENOMEM";
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audit_info = 0;
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goto out;
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}
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if (violation) /* invalidate pcr */
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memset(digest, 0xff, sizeof digest);
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tpmresult = ima_pcr_extend(digest);
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if (tpmresult != 0) {
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snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
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tpmresult);
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audit_cause = tpm_audit_cause;
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audit_info = 0;
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}
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out:
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mutex_unlock(&ima_extend_list_mutex);
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integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
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entry->template.file_name,
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op, audit_cause, result, audit_info);
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return result;
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}
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