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 "ima.h"
  24
  25 LIST_HEAD(ima_measurements);    /* list of all measurements */
  26
  27 /* key: inode (before secure-hashing a file) */
  28 struct ima_h_table ima_htable = {
  29         .len = ATOMIC_LONG_INIT(0),
  30         .violations = ATOMIC_LONG_INIT(0),
  31         .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
  32 };
  33
  34 /* mutex protects atomicity of extending measurement list
  35  * and extending the TPM PCR aggregate. Since tpm_extend can take
  36  * long (and the tpm driver uses a mutex), we can't use the spinlock.
  37  */
  38 static DEFINE_MUTEX(ima_extend_list_mutex);
  39
  40 /* lookup up the digest value in the hash table, and return the entry */
  41 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
  42 {
  43         struct ima_queue_entry *qe, *ret = NULL;
  44         unsigned int key;
  45         struct hlist_node *pos;
  46         int rc;
  47
  48         key = ima_hash_key(digest_value);
  49         rcu_read_lock();
  50         hlist_for_each_entry_rcu(qe, pos, &ima_htable.queue[key], hnext) {
  51                 rc = memcmp(qe->entry->digest, digest_value, IMA_DIGEST_SIZE);
  52                 if (rc == 0) {
  53                         ret = qe;
  54                         break;
  55                 }
  56         }
  57         rcu_read_unlock();
  58         return ret;
  59 }
  60
  61 /* ima_add_template_entry helper function:
  62  * - Add template entry to measurement list and hash table.
  63  *
  64  * (Called with ima_extend_list_mutex held.)
  65  */
  66 static int ima_add_digest_entry(struct ima_template_entry *entry)
  67 {
  68         struct ima_queue_entry *qe;
  69         unsigned int key;
  70
  71         qe = kmalloc(sizeof(*qe), GFP_KERNEL);
  72         if (qe == NULL) {
  73                 pr_err("OUT OF MEMORY ERROR creating queue entry.\n");
  74                 return -ENOMEM;
  75         }
  76         qe->entry = entry;
  77
  78         INIT_LIST_HEAD(&qe->later);
  79         list_add_tail_rcu(&qe->later, &ima_measurements);
  80
  81         atomic_long_inc(&ima_htable.len);
  82         key = ima_hash_key(entry->digest);
  83         hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
  84         return 0;
  85 }
  86
  87 static int ima_pcr_extend(const u8 *hash)
  88 {
  89         int result = 0;
  90
  91         if (!ima_used_chip)
  92                 return result;
  93
  94         result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
  95         if (result != 0)
  96                 pr_err("Error Communicating to TPM chip\n");
  97         return result;
  98 }
  99
 100 /* Add template entry to the measurement list and hash table,
 101  * and extend the pcr.
 102  */
 103 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
 104                            const char *op, struct inode *inode)
 105 {
 106         u8 digest[IMA_DIGEST_SIZE];
 107         const char *audit_cause = "hash_added";
 108         int audit_info = 1;
 109         int result = 0;
 110
 111         mutex_lock(&ima_extend_list_mutex);
 112         if (!violation) {
 113                 memcpy(digest, entry->digest, sizeof digest);
 114                 if (ima_lookup_digest_entry(digest)) {
 115                         audit_cause = "hash_exists";
 116                         goto out;
 117                 }
 118         }
 119
 120         result = ima_add_digest_entry(entry);
 121         if (result < 0) {
 122                 audit_cause = "ENOMEM";
 123                 audit_info = 0;
 124                 goto out;
 125         }
 126
 127         if (violation)          /* invalidate pcr */
 128                 memset(digest, 0xff, sizeof digest);
 129
 130         result = ima_pcr_extend(digest);
 131         if (result != 0) {
 132                 audit_cause = "TPM error";
 133                 audit_info = 0;
 134         }
 135 out:
 136         mutex_unlock(&ima_extend_list_mutex);
 137         integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
 138                             entry->template.file_name,
 139                             op, audit_cause, result, audit_info);
 140         return result;
 141 }