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: digest_value); |
56 | rcu_read_lock(); |
57 | hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) { |
58 | rc = memcmp(p: qe->entry->digests[ima_hash_algo_idx].digest, |
59 | q: digest_value, size: 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(size: 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(list: &qe->later); |
107 | list_add_tail_rcu(new: &qe->later, head: &ima_measurements); |
108 | |
109 | atomic_long_inc(v: &ima_htable.len); |
110 | if (update_htable) { |
111 | key = ima_hash_key(digest: entry->digests[ima_hash_algo_idx].digest); |
112 | hlist_add_head_rcu(n: &qe->hnext, h: &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(chip: ima_tpm_chip, pcr_idx: pcr, digests: 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_value: digest, pcr: entry->pcr)) { |
173 | audit_cause = "hash_exists" ; |
174 | result = -EEXIST; |
175 | goto out; |
176 | } |
177 | } |
178 | |
179 | result = ima_add_digest_entry(entry, |
180 | update_htable: !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, pcr: entry->pcr); |
191 | if (tpmresult != 0) { |
192 | snprintf(buf: tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, fmt: "TPM_error(%d)" , |
193 | tpmresult); |
194 | audit_cause = tpm_audit_cause; |
195 | audit_info = 0; |
196 | } |
197 | out: |
198 | mutex_unlock(lock: &ima_extend_list_mutex); |
199 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, fname: filename, |
200 | op, cause: audit_cause, result, info: 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, update_htable: 0); |
210 | mutex_unlock(lock: &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(n: ima_tpm_chip->nr_allocated_banks, size: 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 | } |
242 | |