root/security/integrity/ima/ima_queue.c

DEFINITIONS

1. ima_lookup_digest_entry
2. get_binary_runtime_size
3. ima_add_digest_entry
4. ima_get_binary_runtime_size
5. ima_pcr_extend
6. ima_add_template_entry
7. ima_restore_measurement_entry
8. ima_init_digests

   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 }