1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 4 * 5 * Authors: 6 * Serge Hallyn <serue@us.ibm.com> 7 * Reiner Sailer <sailer@watson.ibm.com> 8 * Mimi Zohar <zohar@us.ibm.com> 9 * 10 * File: ima_queue.c 11 * Implements queues that store template measurements and 12 * maintains aggregate over the stored measurements 13 * in the pre-configured TPM PCR (if available). 14 * The measurement list is append-only. No entry is 15 * ever removed or changed during the boot-cycle. 16 */ 17 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 19 20 #include <linux/rculist.h> 21 #include <linux/slab.h> 22 #include "ima.h" 23 24 #define AUDIT_CAUSE_LEN_MAX 32 25 26 /* pre-allocated array of tpm_digest structures to extend a PCR */ 27 static struct tpm_digest *digests; 28 29 LIST_HEAD(ima_measurements); /* list of all measurements */ 30 #ifdef CONFIG_IMA_KEXEC 31 static unsigned long binary_runtime_size; 32 #else 33 static unsigned long binary_runtime_size = ULONG_MAX; 34 #endif 35 36 /* key: inode (before secure-hashing a file) */ 37 struct ima_h_table ima_htable = { 38 .len = ATOMIC_LONG_INIT(0), 39 .violations = ATOMIC_LONG_INIT(0), 40 .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT 41 }; 42 43 /* mutex protects atomicity of extending measurement list 44 * and extending the TPM PCR aggregate. Since tpm_extend can take 45 * long (and the tpm driver uses a mutex), we can't use the spinlock. 46 */ 47 static DEFINE_MUTEX(ima_extend_list_mutex); 48 49 /* lookup up the digest value in the hash table, and return the entry */ 50 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, 51 int pcr) 52 { 53 struct ima_queue_entry *qe, *ret = NULL; 54 unsigned int key; 55 int rc; 56 57 key = ima_hash_key(digest_value); 58 rcu_read_lock(); 59 hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { 60 rc = memcmp(qe->entry->digest, digest_value, TPM_DIGEST_SIZE); 61 if ((rc == 0) && (qe->entry->pcr == pcr)) { 62 ret = qe; 63 break; 64 } 65 } 66 rcu_read_unlock(); 67 return ret; 68 } 69 70 /* 71 * Calculate the memory required for serializing a single 72 * binary_runtime_measurement list entry, which contains a 73 * couple of variable length fields (e.g template name and data). 74 */ 75 static int get_binary_runtime_size(struct ima_template_entry *entry) 76 { 77 int size = 0; 78 79 size += sizeof(u32); /* pcr */ 80 size += sizeof(entry->digest); 81 size += sizeof(int); /* template name size field */ 82 size += strlen(entry->template_desc->name); 83 size += sizeof(entry->template_data_len); 84 size += entry->template_data_len; 85 return size; 86 } 87 88 /* ima_add_template_entry helper function: 89 * - Add template entry to the measurement list and hash table, for 90 * all entries except those carried across kexec. 91 * 92 * (Called with ima_extend_list_mutex held.) 93 */ 94 static int ima_add_digest_entry(struct ima_template_entry *entry, 95 bool update_htable) 96 { 97 struct ima_queue_entry *qe; 98 unsigned int key; 99 100 qe = kmalloc(sizeof(*qe), GFP_KERNEL); 101 if (qe == NULL) { 102 pr_err("OUT OF MEMORY ERROR creating queue entry\n"); 103 return -ENOMEM; 104 } 105 qe->entry = entry; 106 107 INIT_LIST_HEAD(&qe->later); 108 list_add_tail_rcu(&qe->later, &ima_measurements); 109 110 atomic_long_inc(&ima_htable.len); 111 if (update_htable) { 112 key = ima_hash_key(entry->digest); 113 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]); 114 } 115 116 if (binary_runtime_size != ULONG_MAX) { 117 int size; 118 119 size = get_binary_runtime_size(entry); 120 binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ? 121 binary_runtime_size + size : ULONG_MAX; 122 } 123 return 0; 124 } 125 126 /* 127 * Return the amount of memory required for serializing the 128 * entire binary_runtime_measurement list, including the ima_kexec_hdr 129 * structure. 130 */ 131 unsigned long ima_get_binary_runtime_size(void) 132 { 133 if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr))) 134 return ULONG_MAX; 135 else 136 return binary_runtime_size + sizeof(struct ima_kexec_hdr); 137 }; 138 139 static int ima_pcr_extend(const u8 *hash, int pcr) 140 { 141 int result = 0; 142 int i; 143 144 if (!ima_tpm_chip) 145 return result; 146 147 for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) 148 memcpy(digests[i].digest, hash, TPM_DIGEST_SIZE); 149 150 result = tpm_pcr_extend(ima_tpm_chip, pcr, digests); 151 if (result != 0) 152 pr_err("Error Communicating to TPM chip, result: %d\n", result); 153 return result; 154 } 155 156 /* 157 * Add template entry to the measurement list and hash table, and 158 * extend the pcr. 159 * 160 * On systems which support carrying the IMA measurement list across 161 * kexec, maintain the total memory size required for serializing the 162 * binary_runtime_measurements. 163 */ 164 int ima_add_template_entry(struct ima_template_entry *entry, int violation, 165 const char *op, struct inode *inode, 166 const unsigned char *filename) 167 { 168 u8 digest[TPM_DIGEST_SIZE]; 169 const char *audit_cause = "hash_added"; 170 char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX]; 171 int audit_info = 1; 172 int result = 0, tpmresult = 0; 173 174 mutex_lock(&ima_extend_list_mutex); 175 if (!violation) { 176 memcpy(digest, entry->digest, sizeof(digest)); 177 if (ima_lookup_digest_entry(digest, entry->pcr)) { 178 audit_cause = "hash_exists"; 179 result = -EEXIST; 180 goto out; 181 } 182 } 183 184 result = ima_add_digest_entry(entry, 1); 185 if (result < 0) { 186 audit_cause = "ENOMEM"; 187 audit_info = 0; 188 goto out; 189 } 190 191 if (violation) /* invalidate pcr */ 192 memset(digest, 0xff, sizeof(digest)); 193 194 tpmresult = ima_pcr_extend(digest, entry->pcr); 195 if (tpmresult != 0) { 196 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)", 197 tpmresult); 198 audit_cause = tpm_audit_cause; 199 audit_info = 0; 200 } 201 out: 202 mutex_unlock(&ima_extend_list_mutex); 203 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, 204 op, audit_cause, result, audit_info); 205 return result; 206 } 207 208 int ima_restore_measurement_entry(struct ima_template_entry *entry) 209 { 210 int result = 0; 211 212 mutex_lock(&ima_extend_list_mutex); 213 result = ima_add_digest_entry(entry, 0); 214 mutex_unlock(&ima_extend_list_mutex); 215 return result; 216 } 217 218 int __init ima_init_digests(void) 219 { 220 int i; 221 222 if (!ima_tpm_chip) 223 return 0; 224 225 digests = kcalloc(ima_tpm_chip->nr_allocated_banks, sizeof(*digests), 226 GFP_NOFS); 227 if (!digests) 228 return -ENOMEM; 229 230 for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) 231 digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id; 232 233 return 0; 234 } 235