security/integrity/ima/ima_queue.c

   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 #include <linux/rculist.h>
  19 #include <linux/slab.h>
  20 #include "ima.h"
  21
  22 #define AUDIT_CAUSE_LEN_MAX 32
  23
  24 /* pre-allocated array of tpm_digest structures to extend a PCR */
  25 static struct tpm_digest *digests;
  26
  27 LIST_HEAD(ima_measurements);    /* list of all measurements */
  28 #ifdef CONFIG_IMA_KEXEC
  29 static unsigned long binary_runtime_size;
  30 #else
  31 static unsigned long binary_runtime_size = ULONG_MAX;
  32 #endif
  33
  34 /* key: inode (before secure-hashing a file) */
  35 struct ima_h_table ima_htable = {
  36         .len = ATOMIC_LONG_INIT(0),
  37         .violations = ATOMIC_LONG_INIT(0),
  38         .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
  39 };
  40
  41 /* mutex protects atomicity of extending measurement list
  42  * and extending the TPM PCR aggregate. Since tpm_extend can take
  43  * long (and the tpm driver uses a mutex), we can't use the spinlock.
  44  */
  45 static DEFINE_MUTEX(ima_extend_list_mutex);
  46
  47 /* lookup up the digest value in the hash table, and return the entry */
  48 static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
  49                                                        int pcr)
  50 {
  51         struct ima_queue_entry *qe, *ret = NULL;
  52         unsigned int key;
  53         int rc;
  54
  55         key = ima_hash_key(digest_value);
  56         rcu_read_lock();
  57         hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
  58                 rc = memcmp(qe->entry->digests[ima_hash_algo_idx].digest,
  59                             digest_value, hash_digest_size[ima_hash_algo]);
  60                 if ((rc == 0) && (qe->entry->pcr == pcr)) {
  61                         ret = qe;
  62                         break;
  63                 }
  64         }
  65         rcu_read_unlock();
  66         return ret;
  67 }
  68
  69 /*
  70  * Calculate the memory required for serializing a single
  71  * binary_runtime_measurement list entry, which contains a
  72  * couple of variable length fields (e.g template name and data).
  73  */
  74 static int get_binary_runtime_size(struct ima_template_entry *entry)
  75 {
  76         int size = 0;
  77
  78         size += sizeof(u32);    /* pcr */
  79         size += TPM_DIGEST_SIZE;
  80         size += sizeof(int);    /* template name size field */
  81         size += strlen(entry->template_desc->name);
  82         size += sizeof(entry->template_data_len);
  83         size += entry->template_data_len;
  84         return size;
  85 }
  86
  87 /* ima_add_template_entry helper function:
  88  * - Add template entry to the measurement list and hash table, for
  89  *   all entries except those carried across kexec.
  90  *
  91  * (Called with ima_extend_list_mutex held.)
  92  */
  93 static int ima_add_digest_entry(struct ima_template_entry *entry,
  94                                 bool update_htable)
  95 {
  96         struct ima_queue_entry *qe;
  97         unsigned int key;
  98
  99         qe = kmalloc(sizeof(*qe), GFP_KERNEL);
 100         if (qe == NULL) {
 101                 pr_err("OUT OF MEMORY ERROR creating queue entry\n");
 102                 return -ENOMEM;
 103         }
 104         qe->entry = entry;
 105
 106         INIT_LIST_HEAD(&qe->later);
 107         list_add_tail_rcu(&qe->later, &ima_measurements);
 108
 109         atomic_long_inc(&ima_htable.len);
 110         if (update_htable) {
 111                 key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
 112                 hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
 113         }
 114
 115         if (binary_runtime_size != ULONG_MAX) {
 116                 int size;
 117
 118                 size = get_binary_runtime_size(entry);
 119                 binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
 120                      binary_runtime_size + size : ULONG_MAX;
 121         }
 122         return 0;
 123 }
 124
 125 /*
 126  * Return the amount of memory required for serializing the
 127  * entire binary_runtime_measurement list, including the ima_kexec_hdr
 128  * structure.
 129  */
 130 unsigned long ima_get_binary_runtime_size(void)
 131 {
 132         if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
 133                 return ULONG_MAX;
 134         else
 135                 return binary_runtime_size + sizeof(struct ima_kexec_hdr);
 136 }
 137
 138 static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
 139 {
 140         int result = 0;
 141
 142         if (!ima_tpm_chip)
 143                 return result;
 144
 145         result = tpm_pcr_extend(ima_tpm_chip, pcr, digests_arg);
 146         if (result != 0)
 147                 pr_err("Error Communicating to TPM chip, result: %d\n", result);
 148         return result;
 149 }
 150
 151 /*
 152  * Add template entry to the measurement list and hash table, and
 153  * extend the pcr.
 154  *
 155  * On systems which support carrying the IMA measurement list across
 156  * kexec, maintain the total memory size required for serializing the
 157  * binary_runtime_measurements.
 158  */
 159 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
 160                            const char *op, struct inode *inode,
 161                            const unsigned char *filename)
 162 {
 163         u8 *digest = entry->digests[ima_hash_algo_idx].digest;
 164         struct tpm_digest *digests_arg = entry->digests;
 165         const char *audit_cause = "hash_added";
 166         char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
 167         int audit_info = 1;
 168         int result = 0, tpmresult = 0;
 169
 170         mutex_lock(&ima_extend_list_mutex);
 171         if (!violation && !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
 172                 if (ima_lookup_digest_entry(digest, entry->pcr)) {
 173                         audit_cause = "hash_exists";
 174                         result = -EEXIST;
 175                         goto out;
 176                 }
 177         }
 178
 179         result = ima_add_digest_entry(entry,
 180                                       !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE));
 181         if (result < 0) {
 182                 audit_cause = "ENOMEM";
 183                 audit_info = 0;
 184                 goto out;
 185         }
 186
 187         if (violation)          /* invalidate pcr */
 188                 digests_arg = digests;
 189
 190         tpmresult = ima_pcr_extend(digests_arg, entry->pcr);
 191         if (tpmresult != 0) {
 192                 snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
 193                          tpmresult);
 194                 audit_cause = tpm_audit_cause;
 195                 audit_info = 0;
 196         }
 197 out:
 198         mutex_unlock(&ima_extend_list_mutex);
 199         integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
 200                             op, audit_cause, result, audit_info);
 201         return result;
 202 }
 203
 204 int ima_restore_measurement_entry(struct ima_template_entry *entry)
 205 {
 206         int result = 0;
 207
 208         mutex_lock(&ima_extend_list_mutex);
 209         result = ima_add_digest_entry(entry, 0);
 210         mutex_unlock(&ima_extend_list_mutex);
 211         return result;
 212 }
 213
 214 int __init ima_init_digests(void)
 215 {
 216         u16 digest_size;
 217         u16 crypto_id;
 218         int i;
 219
 220         if (!ima_tpm_chip)
 221                 return 0;
 222
 223         digests = kcalloc(ima_tpm_chip->nr_allocated_banks, sizeof(*digests),
 224                           GFP_NOFS);
 225         if (!digests)
 226                 return -ENOMEM;
 227
 228         for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
 229                 digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
 230                 digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
 231                 crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
 232
 233                 /* for unmapped TPM algorithms digest is still a padded SHA1 */
 234                 if (crypto_id == HASH_ALGO__LAST)
 235                         digest_size = SHA1_DIGEST_SIZE;
 236
 237                 memset(digests[i].digest, 0xff, digest_size);
 238         }
 239
 240         return 0;
 241 }