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/rculist.h> 25 #include <linux/slab.h> 26 #include "ima.h" 27 28 #define AUDIT_CAUSE_LEN_MAX 32 29 30 LIST_HEAD(ima_measurements); /* list of all measurements */ 31 #ifdef CONFIG_IMA_KEXEC 32 static unsigned long binary_runtime_size; 33 #else 34 static unsigned long binary_runtime_size = ULONG_MAX; 35 #endif 36 37 /* key: inode (before secure-hashing a file) */ 38 struct ima_h_table ima_htable = { 39 .len = ATOMIC_LONG_INIT(0), 40 .violations = ATOMIC_LONG_INIT(0), 41 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT 42 }; 43 44 /* mutex protects atomicity of extending measurement list 45 * and extending the TPM PCR aggregate. Since tpm_extend can take 46 * long (and the tpm driver uses a mutex), we can't use the spinlock. 47 */ 48 static DEFINE_MUTEX(ima_extend_list_mutex); 49 50 /* lookup up the digest value in the hash table, and return the entry */ 51 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, 52 int pcr) 53 { 54 struct ima_queue_entry *qe, *ret = NULL; 55 unsigned int key; 56 int rc; 57 58 key = ima_hash_key(digest_value); 59 rcu_read_lock(); 60 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { 61 rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); 62 if ((rc == 0) && (qe->entry->pcr == pcr)) { 63 ret = qe; 64 break; 65 } 66 } 67 rcu_read_unlock(); 68 return ret; 69 } 70 71 /* 72 * Calculate the memory required for serializing a single 73 * binary_runtime_measurement list entry, which contains a 74 * couple of variable length fields (e.g template name and data). 75 */ 76 static int get_binary_runtime_size(struct ima_template_entry *entry) 77 { 78 int size = 0; 79 80 size += sizeof(u32); /* pcr */ 81 size += sizeof(entry->digest); 82 size += sizeof(int); /* template name size field */ 83 size += strlen(entry->template_desc->name); 84 size += sizeof(entry->template_data_len); 85 size += entry->template_data_len; 86 return size; 87 } 88 89 /* ima_add_template_entry helper function: 90 * - Add template entry to the measurement list and hash table, for 91 * all entries except those carried across kexec. 92 * 93 * (Called with ima_extend_list_mutex held.) 94 */ 95 static int ima_add_digest_entry(struct ima_template_entry *entry, 96 bool update_htable) 97 { 98 struct ima_queue_entry *qe; 99 unsigned int key; 100 101 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 102 if (qe == NULL) { 103 pr_err("OUT OF MEMORY ERROR creating queue entry\n"); 104 return -ENOMEM; 105 } 106 qe->entry = entry; 107 108 INIT_LIST_HEAD(&qe->later); 109 list_add_tail_rcu(&qe->later, &ima_measurements); 110 111 atomic_long_inc(&ima_htable.len); 112 if (update_htable) { 113 key = ima_hash_key(entry->digest); 114 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 115 } 116 117 if (binary_runtime_size != ULONG_MAX) { 118 int size; 119 120 size = get_binary_runtime_size(entry); 121 binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ? 122 binary_runtime_size + size : ULONG_MAX; 123 } 124 return 0; 125 } 126 127 /* 128 * Return the amount of memory required for serializing the 129 * entire binary_runtime_measurement list, including the ima_kexec_hdr 130 * structure. 131 */ 132 unsigned long ima_get_binary_runtime_size(void) 133 { 134 if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr))) 135 return ULONG_MAX; 136 else 137 return binary_runtime_size + sizeof(struct ima_kexec_hdr); 138 }; 139 140 static int ima_pcr_extend(const u8 *hash, int pcr) 141 { 142 int result = 0; 143 144 if (!ima_tpm_chip) 145 return result; 146 147 result = tpm_pcr_extend(ima_tpm_chip, pcr, hash); 148 if (result != 0) 149 pr_err("Error Communicating to TPM chip, result: %d\n", result); 150 return result; 151 } 152 153 /* 154 * Add template entry to the measurement list and hash table, and 155 * extend the pcr. 156 * 157 * On systems which support carrying the IMA measurement list across 158 * kexec, maintain the total memory size required for serializing the 159 * binary_runtime_measurements. 160 */ 161 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 162 const char *op, struct inode *inode, 163 const unsigned char *filename) 164 { 165 u8 digest[TPM_DIGEST_SIZE]; 166 const char *audit_cause = "hash_added"; 167 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 168 int audit_info = 1; 169 int result = 0, tpmresult = 0; 170 171 mutex_lock(&ima_extend_list_mutex); 172 if (!violation) { 173 memcpy(digest, entry->digest, sizeof(digest)); 174 if (ima_lookup_digest_entry(digest, entry->pcr)) { 175 audit_cause = "hash_exists"; 176 result = -EEXIST; 177 goto out; 178 } 179 } 180 181 result = ima_add_digest_entry(entry, 1); 182 if (result < 0) { 183 audit_cause = "ENOMEM"; 184 audit_info = 0; 185 goto out; 186 } 187 188 if (violation) /* invalidate pcr */ 189 memset(digest, 0xff, sizeof(digest)); 190 191 tpmresult = ima_pcr_extend(digest, entry->pcr); 192 if (tpmresult != 0) { 193 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 194 tpmresult); 195 audit_cause = tpm_audit_cause; 196 audit_info = 0; 197 } 198 out: 199 mutex_unlock(&ima_extend_list_mutex); 200 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 201 op, audit_cause, result, audit_info); 202 return result; 203 } 204 205 int ima_restore_measurement_entry(struct ima_template_entry *entry) 206 { 207 int result = 0; 208 209 mutex_lock(&ima_extend_list_mutex); 210 result = ima_add_digest_entry(entry, 0); 211 mutex_unlock(&ima_extend_list_mutex); 212 return result; 213 } 214