1 /* 2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 3 * 4 * Authors: 5 * Serge Hallyn <[email protected]> 6 * Reiner Sailer <[email protected]> 7 * Mimi Zohar <[email protected]> 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 the measurement list and hash table, for 69 * all entries except those carried across kexec. 70 * 71 * (Called with ima_extend_list_mutex held.) 72 */ 73 static int ima_add_digest_entry(struct ima_template_entry *entry, 74 bool update_htable) 75 { 76 struct ima_queue_entry *qe; 77 unsigned int key; 78 79 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 80 if (qe == NULL) { 81 pr_err("OUT OF MEMORY ERROR creating queue entry\n"); 82 return -ENOMEM; 83 } 84 qe->entry = entry; 85 86 INIT_LIST_HEAD(&qe->later); 87 list_add_tail_rcu(&qe->later, &ima_measurements); 88 89 atomic_long_inc(&ima_htable.len); 90 if (update_htable) { 91 key = ima_hash_key(entry->digest); 92 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 93 } 94 return 0; 95 } 96 97 static int ima_pcr_extend(const u8 *hash, int pcr) 98 { 99 int result = 0; 100 101 if (!ima_used_chip) 102 return result; 103 104 result = tpm_pcr_extend(TPM_ANY_NUM, pcr, hash); 105 if (result != 0) 106 pr_err("Error Communicating to TPM chip, result: %d\n", result); 107 return result; 108 } 109 110 /* Add template entry to the measurement list and hash table, 111 * and extend the pcr. 112 */ 113 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 114 const char *op, struct inode *inode, 115 const unsigned char *filename) 116 { 117 u8 digest[TPM_DIGEST_SIZE]; 118 const char *audit_cause = "hash_added"; 119 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 120 int audit_info = 1; 121 int result = 0, tpmresult = 0; 122 123 mutex_lock(&ima_extend_list_mutex); 124 if (!violation) { 125 memcpy(digest, entry->digest, sizeof(digest)); 126 if (ima_lookup_digest_entry(digest, entry->pcr)) { 127 audit_cause = "hash_exists"; 128 result = -EEXIST; 129 goto out; 130 } 131 } 132 133 result = ima_add_digest_entry(entry, 1); 134 if (result < 0) { 135 audit_cause = "ENOMEM"; 136 audit_info = 0; 137 goto out; 138 } 139 140 if (violation) /* invalidate pcr */ 141 memset(digest, 0xff, sizeof(digest)); 142 143 tpmresult = ima_pcr_extend(digest, entry->pcr); 144 if (tpmresult != 0) { 145 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 146 tpmresult); 147 audit_cause = tpm_audit_cause; 148 audit_info = 0; 149 } 150 out: 151 mutex_unlock(&ima_extend_list_mutex); 152 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 153 op, audit_cause, result, audit_info); 154 return result; 155 } 156 157 int ima_restore_measurement_entry(struct ima_template_entry *entry) 158 { 159 int result = 0; 160 161 mutex_lock(&ima_extend_list_mutex); 162 result = ima_add_digest_entry(entry, 0); 163 mutex_unlock(&ima_extend_list_mutex); 164 return result; 165 } 166