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 26 #define AUDIT_CAUSE_LEN_MAX 32 27 28 LIST_HEAD(ima_measurements); /* list of all measurements */ 29 30 /* key: inode (before secure-hashing a file) */ 31 struct ima_h_table ima_htable = { 32 .len = ATOMIC_LONG_INIT(0), 33 .violations = ATOMIC_LONG_INIT(0), 34 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT 35 }; 36 37 /* mutex protects atomicity of extending measurement list 38 * and extending the TPM PCR aggregate. Since tpm_extend can take 39 * long (and the tpm driver uses a mutex), we can't use the spinlock. 40 */ 41 static DEFINE_MUTEX(ima_extend_list_mutex); 42 43 /* lookup up the digest value in the hash table, and return the entry */ 44 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value) 45 { 46 struct ima_queue_entry *qe, *ret = NULL; 47 unsigned int key; 48 int rc; 49 50 key = ima_hash_key(digest_value); 51 rcu_read_lock(); 52 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { 53 rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); 54 if (rc == 0) { 55 ret = qe; 56 break; 57 } 58 } 59 rcu_read_unlock(); 60 return ret; 61 } 62 63 /* ima_add_template_entry helper function: 64 * - Add template entry to measurement list and hash table. 65 * 66 * (Called with ima_extend_list_mutex held.) 67 */ 68 static int ima_add_digest_entry(struct ima_template_entry *entry) 69 { 70 struct ima_queue_entry *qe; 71 unsigned int key; 72 73 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 74 if (qe == NULL) { 75 pr_err("IMA: OUT OF MEMORY ERROR creating queue entry.\n"); 76 return -ENOMEM; 77 } 78 qe->entry = entry; 79 80 INIT_LIST_HEAD(&qe->later); 81 list_add_tail_rcu(&qe->later, &ima_measurements); 82 83 atomic_long_inc(&ima_htable.len); 84 key = ima_hash_key(entry->digest); 85 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 86 return 0; 87 } 88 89 static int ima_pcr_extend(const u8 *hash) 90 { 91 int result = 0; 92 93 if (!ima_used_chip) 94 return result; 95 96 result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash); 97 if (result != 0) 98 pr_err("IMA: Error Communicating to TPM chip, result: %d\n", 99 result); 100 return result; 101 } 102 103 /* Add template entry to the measurement list and hash table, 104 * and extend the pcr. 105 */ 106 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 107 const char *op, struct inode *inode, 108 const unsigned char *filename) 109 { 110 u8 digest[TPM_DIGEST_SIZE]; 111 const char *audit_cause = "hash_added"; 112 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 113 int audit_info = 1; 114 int result = 0, tpmresult = 0; 115 116 mutex_lock(&ima_extend_list_mutex); 117 if (!violation) { 118 memcpy(digest, entry->digest, sizeof digest); 119 if (ima_lookup_digest_entry(digest)) { 120 audit_cause = "hash_exists"; 121 result = -EEXIST; 122 goto out; 123 } 124 } 125 126 result = ima_add_digest_entry(entry); 127 if (result < 0) { 128 audit_cause = "ENOMEM"; 129 audit_info = 0; 130 goto out; 131 } 132 133 if (violation) /* invalidate pcr */ 134 memset(digest, 0xff, sizeof digest); 135 136 tpmresult = ima_pcr_extend(digest); 137 if (tpmresult != 0) { 138 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 139 tpmresult); 140 audit_cause = tpm_audit_cause; 141 audit_info = 0; 142 } 143 out: 144 mutex_unlock(&ima_extend_list_mutex); 145 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 146 op, audit_cause, result, audit_info); 147 return result; 148 } 149