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 { 49 struct ima_queue_entry *qe, *ret = NULL; 50 unsigned int key; 51 int rc; 52 53 key = ima_hash_key(digest_value); 54 rcu_read_lock(); 55 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { 56 rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); 57 if (rc == 0) { 58 ret = qe; 59 break; 60 } 61 } 62 rcu_read_unlock(); 63 return ret; 64 } 65 66 /* ima_add_template_entry helper function: 67 * - Add template entry to measurement list and hash table. 68 * 69 * (Called with ima_extend_list_mutex held.) 70 */ 71 static int ima_add_digest_entry(struct ima_template_entry *entry) 72 { 73 struct ima_queue_entry *qe; 74 unsigned int key; 75 76 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 77 if (qe == NULL) { 78 pr_err("OUT OF MEMORY ERROR creating queue entry\n"); 79 return -ENOMEM; 80 } 81 qe->entry = entry; 82 83 INIT_LIST_HEAD(&qe->later); 84 list_add_tail_rcu(&qe->later, &ima_measurements); 85 86 atomic_long_inc(&ima_htable.len); 87 key = ima_hash_key(entry->digest); 88 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 89 return 0; 90 } 91 92 static int ima_pcr_extend(const u8 *hash) 93 { 94 int result = 0; 95 96 if (!ima_used_chip) 97 return result; 98 99 result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash); 100 if (result != 0) 101 pr_err("Error Communicating to TPM chip, result: %d\n", result); 102 return result; 103 } 104 105 /* Add template entry to the measurement list and hash table, 106 * and extend the pcr. 107 */ 108 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 109 const char *op, struct inode *inode, 110 const unsigned char *filename) 111 { 112 u8 digest[TPM_DIGEST_SIZE]; 113 const char *audit_cause = "hash_added"; 114 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 115 int audit_info = 1; 116 int result = 0, tpmresult = 0; 117 118 mutex_lock(&ima_extend_list_mutex); 119 if (!violation) { 120 memcpy(digest, entry->digest, sizeof(digest)); 121 if (ima_lookup_digest_entry(digest)) { 122 audit_cause = "hash_exists"; 123 result = -EEXIST; 124 goto out; 125 } 126 } 127 128 result = ima_add_digest_entry(entry); 129 if (result < 0) { 130 audit_cause = "ENOMEM"; 131 audit_info = 0; 132 goto out; 133 } 134 135 if (violation) /* invalidate pcr */ 136 memset(digest, 0xff, sizeof(digest)); 137 138 tpmresult = ima_pcr_extend(digest); 139 if (tpmresult != 0) { 140 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 141 tpmresult); 142 audit_cause = tpm_audit_cause; 143 audit_info = 0; 144 } 145 out: 146 mutex_unlock(&ima_extend_list_mutex); 147 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 148 op, audit_cause, result, audit_info); 149 return result; 150 } 151