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 */
ima_lookup_digest_entry(u8 * digest_value,int pcr)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 */
get_binary_runtime_size(struct ima_template_entry * entry)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 */
ima_add_digest_entry(struct ima_template_entry * entry,bool update_htable)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 */
ima_get_binary_runtime_size(void)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
ima_pcr_extend(const u8 * hash,int pcr)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 */
ima_add_template_entry(struct ima_template_entry * entry,int violation,const char * op,struct inode * inode,const unsigned char * filename)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
ima_restore_measurement_entry(struct ima_template_entry * entry)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
ima_init_digests(void)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