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 22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 23 24 #include <linux/module.h> 25 #include <linux/rculist.h> 26 #include <linux/slab.h> 27 #include "ima.h" 28 29 #define AUDIT_CAUSE_LEN_MAX 32 30 31 LIST_HEAD(ima_measurements); /* list of all measurements */ 32 33 /* key: inode (before secure-hashing a file) */ 34 struct ima_h_table ima_htable = { 35 .len = ATOMIC_LONG_INIT(0), 36 .violations = ATOMIC_LONG_INIT(0), 37 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT 38 }; 39 40 /* mutex protects atomicity of extending measurement list 41 * and extending the TPM PCR aggregate. Since tpm_extend can take 42 * long (and the tpm driver uses a mutex), we can't use the spinlock. 43 */ 44 static DEFINE_MUTEX(ima_extend_list_mutex); 45 46 /* lookup up the digest value in the hash table, and return the entry */ 47 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, 48 int pcr) 49 { 50 struct ima_queue_entry *qe, *ret = NULL; 51 unsigned int key; 52 int rc; 53 54 key = ima_hash_key(digest_value); 55 rcu_read_lock(); 56 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { 57 rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); 58 if ((rc == 0) && (qe->entry->pcr == pcr)) { 59 ret = qe; 60 break; 61 } 62 } 63 rcu_read_unlock(); 64 return ret; 65 } 66 67 /* ima_add_template_entry helper function: 68 * - Add template entry to measurement list and hash table. 69 * 70 * (Called with ima_extend_list_mutex held.) 71 */ 72 static int ima_add_digest_entry(struct ima_template_entry *entry) 73 { 74 struct ima_queue_entry *qe; 75 unsigned int key; 76 77 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 78 if (qe == NULL) { 79 pr_err("OUT OF MEMORY ERROR creating queue entry\n"); 80 return -ENOMEM; 81 } 82 qe->entry = entry; 83 84 INIT_LIST_HEAD(&qe->later); 85 list_add_tail_rcu(&qe->later, &ima_measurements); 86 87 atomic_long_inc(&ima_htable.len); 88 key = ima_hash_key(entry->digest); 89 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 90 return 0; 91 } 92 93 static int ima_pcr_extend(const u8 *hash, int pcr) 94 { 95 int result = 0; 96 97 if (!ima_used_chip) 98 return result; 99 100 result = tpm_pcr_extend(TPM_ANY_NUM, pcr, hash); 101 if (result != 0) 102 pr_err("Error Communicating to TPM chip, result: %d\n", result); 103 return result; 104 } 105 106 /* Add template entry to the measurement list and hash table, 107 * and extend the pcr. 108 */ 109 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 110 const char *op, struct inode *inode, 111 const unsigned char *filename) 112 { 113 u8 digest[TPM_DIGEST_SIZE]; 114 const char *audit_cause = "hash_added"; 115 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 116 int audit_info = 1; 117 int result = 0, tpmresult = 0; 118 119 mutex_lock(&ima_extend_list_mutex); 120 if (!violation) { 121 memcpy(digest, entry->digest, sizeof(digest)); 122 if (ima_lookup_digest_entry(digest, entry->pcr)) { 123 audit_cause = "hash_exists"; 124 result = -EEXIST; 125 goto out; 126 } 127 } 128 129 result = ima_add_digest_entry(entry); 130 if (result < 0) { 131 audit_cause = "ENOMEM"; 132 audit_info = 0; 133 goto out; 134 } 135 136 if (violation) /* invalidate pcr */ 137 memset(digest, 0xff, sizeof(digest)); 138 139 tpmresult = ima_pcr_extend(digest, entry->pcr); 140 if (tpmresult != 0) { 141 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 142 tpmresult); 143 audit_cause = tpm_audit_cause; 144 audit_info = 0; 145 } 146 out: 147 mutex_unlock(&ima_extend_list_mutex); 148 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 149 op, audit_cause, result, audit_info); 150 return result; 151 } 152 153 int ima_restore_measurement_entry(struct ima_template_entry *entry) 154 { 155 int result = 0; 156 157 mutex_lock(&ima_extend_list_mutex); 158 result = ima_add_digest_entry(entry); 159 mutex_unlock(&ima_extend_list_mutex); 160 return result; 161 } 162