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 #ifdef CONFIG_IMA_KEXEC 33 static unsigned long binary_runtime_size; 34 #else 35 static unsigned long binary_runtime_size = ULONG_MAX; 36 #endif 37 38 /* key: inode (before secure-hashing a file) */ 39 struct ima_h_table ima_htable = { 40 .len = ATOMIC_LONG_INIT(0), 41 .violations = ATOMIC_LONG_INIT(0), 42 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT 43 }; 44 45 /* mutex protects atomicity of extending measurement list 46 * and extending the TPM PCR aggregate. Since tpm_extend can take 47 * long (and the tpm driver uses a mutex), we can't use the spinlock. 48 */ 49 static DEFINE_MUTEX(ima_extend_list_mutex); 50 51 /* lookup up the digest value in the hash table, and return the entry */ 52 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, 53 int pcr) 54 { 55 struct ima_queue_entry *qe, *ret = NULL; 56 unsigned int key; 57 int rc; 58 59 key = ima_hash_key(digest_value); 60 rcu_read_lock(); 61 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { 62 rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); 63 if ((rc == 0) && (qe->entry->pcr == pcr)) { 64 ret = qe; 65 break; 66 } 67 } 68 rcu_read_unlock(); 69 return ret; 70 } 71 72 /* 73 * Calculate the memory required for serializing a single 74 * binary_runtime_measurement list entry, which contains a 75 * couple of variable length fields (e.g template name and data). 76 */ 77 static int get_binary_runtime_size(struct ima_template_entry *entry) 78 { 79 int size = 0; 80 81 size += sizeof(u32); /* pcr */ 82 size += sizeof(entry->digest); 83 size += sizeof(int); /* template name size field */ 84 size += strlen(entry->template_desc->name); 85 size += sizeof(entry->template_data_len); 86 size += entry->template_data_len; 87 return size; 88 } 89 90 /* ima_add_template_entry helper function: 91 * - Add template entry to the measurement list and hash table, for 92 * all entries except those carried across kexec. 93 * 94 * (Called with ima_extend_list_mutex held.) 95 */ 96 static int ima_add_digest_entry(struct ima_template_entry *entry, 97 bool update_htable) 98 { 99 struct ima_queue_entry *qe; 100 unsigned int key; 101 102 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 103 if (qe == NULL) { 104 pr_err("OUT OF MEMORY ERROR creating queue entry\n"); 105 return -ENOMEM; 106 } 107 qe->entry = entry; 108 109 INIT_LIST_HEAD(&qe->later); 110 list_add_tail_rcu(&qe->later, &ima_measurements); 111 112 atomic_long_inc(&ima_htable.len); 113 if (update_htable) { 114 key = ima_hash_key(entry->digest); 115 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 116 } 117 118 if (binary_runtime_size != ULONG_MAX) { 119 int size; 120 121 size = get_binary_runtime_size(entry); 122 binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ? 123 binary_runtime_size + size : ULONG_MAX; 124 } 125 return 0; 126 } 127 128 /* 129 * Return the amount of memory required for serializing the 130 * entire binary_runtime_measurement list, including the ima_kexec_hdr 131 * structure. 132 */ 133 unsigned long ima_get_binary_runtime_size(void) 134 { 135 if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr))) 136 return ULONG_MAX; 137 else 138 return binary_runtime_size + sizeof(struct ima_kexec_hdr); 139 }; 140 141 static int ima_pcr_extend(const u8 *hash, int pcr) 142 { 143 int result = 0; 144 145 if (!ima_used_chip) 146 return result; 147 148 result = tpm_pcr_extend(NULL, pcr, hash); 149 if (result != 0) 150 pr_err("Error Communicating to TPM chip, result: %d\n", result); 151 return result; 152 } 153 154 /* 155 * Add template entry to the measurement list and hash table, and 156 * extend the pcr. 157 * 158 * On systems which support carrying the IMA measurement list across 159 * kexec, maintain the total memory size required for serializing the 160 * binary_runtime_measurements. 161 */ 162 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 163 const char *op, struct inode *inode, 164 const unsigned char *filename) 165 { 166 u8 digest[TPM_DIGEST_SIZE]; 167 const char *audit_cause = "hash_added"; 168 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 169 int audit_info = 1; 170 int result = 0, tpmresult = 0; 171 172 mutex_lock(&ima_extend_list_mutex); 173 if (!violation) { 174 memcpy(digest, entry->digest, sizeof(digest)); 175 if (ima_lookup_digest_entry(digest, entry->pcr)) { 176 audit_cause = "hash_exists"; 177 result = -EEXIST; 178 goto out; 179 } 180 } 181 182 result = ima_add_digest_entry(entry, 1); 183 if (result < 0) { 184 audit_cause = "ENOMEM"; 185 audit_info = 0; 186 goto out; 187 } 188 189 if (violation) /* invalidate pcr */ 190 memset(digest, 0xff, sizeof(digest)); 191 192 tpmresult = ima_pcr_extend(digest, entry->pcr); 193 if (tpmresult != 0) { 194 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 195 tpmresult); 196 audit_cause = tpm_audit_cause; 197 audit_info = 0; 198 } 199 out: 200 mutex_unlock(&ima_extend_list_mutex); 201 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 202 op, audit_cause, result, audit_info); 203 return result; 204 } 205 206 int ima_restore_measurement_entry(struct ima_template_entry *entry) 207 { 208 int result = 0; 209 210 mutex_lock(&ima_extend_list_mutex); 211 result = ima_add_digest_entry(entry, 0); 212 mutex_unlock(&ima_extend_list_mutex); 213 return result; 214 } 215