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3323eec9 MZ |
1 | /* |
2 | * Copyright (C) 2008 IBM Corporation | |
3 | * | |
4 | * Author: Mimi Zohar <zohar@us.ibm.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License as | |
8 | * published by the Free Software Foundation, version 2 of the | |
9 | * License. | |
10 | * | |
11 | * File: ima_api.c | |
2fe5d6de MZ |
12 | * Implements must_appraise_or_measure, collect_measurement, |
13 | * appraise_measurement, store_measurement and store_template. | |
3323eec9 MZ |
14 | */ |
15 | #include <linux/module.h> | |
5a0e3ad6 | 16 | #include <linux/slab.h> |
2fe5d6de MZ |
17 | #include <linux/file.h> |
18 | #include <linux/fs.h> | |
19 | #include <linux/xattr.h> | |
20 | #include <linux/evm.h> | |
1525b06d | 21 | |
3323eec9 | 22 | #include "ima.h" |
2fe5d6de | 23 | |
a7ed7c60 RS |
24 | /* |
25 | * ima_free_template_entry - free an existing template entry | |
26 | */ | |
27 | void ima_free_template_entry(struct ima_template_entry *entry) | |
28 | { | |
29 | int i; | |
30 | ||
31 | for (i = 0; i < entry->template_desc->num_fields; i++) | |
32 | kfree(entry->template_data[i].data); | |
33 | ||
34 | kfree(entry); | |
35 | } | |
36 | ||
7bc5f447 RS |
37 | /* |
38 | * ima_alloc_init_template - create and initialize a new template entry | |
39 | */ | |
23b57419 RS |
40 | int ima_alloc_init_template(struct ima_event_data *event_data, |
41 | struct ima_template_entry **entry) | |
7bc5f447 | 42 | { |
a71dc65d RS |
43 | struct ima_template_desc *template_desc = ima_template_desc_current(); |
44 | int i, result = 0; | |
7bc5f447 | 45 | |
a71dc65d RS |
46 | *entry = kzalloc(sizeof(**entry) + template_desc->num_fields * |
47 | sizeof(struct ima_field_data), GFP_NOFS); | |
48 | if (!*entry) | |
7bc5f447 RS |
49 | return -ENOMEM; |
50 | ||
a7ed7c60 | 51 | (*entry)->template_desc = template_desc; |
a71dc65d RS |
52 | for (i = 0; i < template_desc->num_fields; i++) { |
53 | struct ima_template_field *field = template_desc->fields[i]; | |
54 | u32 len; | |
7bc5f447 | 55 | |
23b57419 | 56 | result = field->field_init(event_data, |
a71dc65d RS |
57 | &((*entry)->template_data[i])); |
58 | if (result != 0) | |
59 | goto out; | |
7bc5f447 | 60 | |
a71dc65d RS |
61 | len = (*entry)->template_data[i].len; |
62 | (*entry)->template_data_len += sizeof(len); | |
63 | (*entry)->template_data_len += len; | |
64 | } | |
7bc5f447 | 65 | return 0; |
a71dc65d | 66 | out: |
a7ed7c60 | 67 | ima_free_template_entry(*entry); |
a71dc65d | 68 | *entry = NULL; |
7bc5f447 RS |
69 | return result; |
70 | } | |
71 | ||
3323eec9 MZ |
72 | /* |
73 | * ima_store_template - store ima template measurements | |
74 | * | |
75 | * Calculate the hash of a template entry, add the template entry | |
76 | * to an ordered list of measurement entries maintained inside the kernel, | |
77 | * and also update the aggregate integrity value (maintained inside the | |
78 | * configured TPM PCR) over the hashes of the current list of measurement | |
79 | * entries. | |
80 | * | |
81 | * Applications retrieve the current kernel-held measurement list through | |
82 | * the securityfs entries in /sys/kernel/security/ima. The signed aggregate | |
83 | * TPM PCR (called quote) can be retrieved using a TPM user space library | |
84 | * and is used to validate the measurement list. | |
85 | * | |
86 | * Returns 0 on success, error code otherwise | |
87 | */ | |
88 | int ima_store_template(struct ima_template_entry *entry, | |
9803d413 RS |
89 | int violation, struct inode *inode, |
90 | const unsigned char *filename) | |
3323eec9 | 91 | { |
52a13284 MZ |
92 | static const char op[] = "add_template_measure"; |
93 | static const char audit_cause[] = "hashing_error"; | |
a71dc65d | 94 | char *template_name = entry->template_desc->name; |
3323eec9 | 95 | int result; |
a35c3fb6 DK |
96 | struct { |
97 | struct ima_digest_data hdr; | |
140d8022 | 98 | char digest[TPM_DIGEST_SIZE]; |
a35c3fb6 | 99 | } hash; |
3323eec9 | 100 | |
3323eec9 | 101 | if (!violation) { |
a71dc65d RS |
102 | int num_fields = entry->template_desc->num_fields; |
103 | ||
ea593993 DK |
104 | /* this function uses default algo */ |
105 | hash.hdr.algo = HASH_ALGO_SHA1; | |
a71dc65d | 106 | result = ima_calc_field_array_hash(&entry->template_data[0], |
b6f8f16f | 107 | entry->template_desc, |
a71dc65d | 108 | num_fields, &hash.hdr); |
3323eec9 MZ |
109 | if (result < 0) { |
110 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, | |
a71dc65d | 111 | template_name, op, |
3323eec9 MZ |
112 | audit_cause, result, 0); |
113 | return result; | |
114 | } | |
a35c3fb6 | 115 | memcpy(entry->digest, hash.hdr.digest, hash.hdr.length); |
3323eec9 | 116 | } |
9803d413 | 117 | result = ima_add_template_entry(entry, violation, op, inode, filename); |
3323eec9 MZ |
118 | return result; |
119 | } | |
120 | ||
121 | /* | |
122 | * ima_add_violation - add violation to measurement list. | |
123 | * | |
124 | * Violations are flagged in the measurement list with zero hash values. | |
125 | * By extending the PCR with 0xFF's instead of with zeroes, the PCR | |
126 | * value is invalidated. | |
127 | */ | |
7d802a22 | 128 | void ima_add_violation(struct file *file, const unsigned char *filename, |
8d94eb9b | 129 | struct integrity_iint_cache *iint, |
3323eec9 MZ |
130 | const char *op, const char *cause) |
131 | { | |
132 | struct ima_template_entry *entry; | |
31d4b761 | 133 | struct inode *inode = file_inode(file); |
8d94eb9b RS |
134 | struct ima_event_data event_data = {iint, file, filename, NULL, 0, |
135 | cause}; | |
3323eec9 MZ |
136 | int violation = 1; |
137 | int result; | |
138 | ||
139 | /* can overflow, only indicator */ | |
140 | atomic_long_inc(&ima_htable.violations); | |
141 | ||
23b57419 | 142 | result = ima_alloc_init_template(&event_data, &entry); |
7bc5f447 | 143 | if (result < 0) { |
3323eec9 MZ |
144 | result = -ENOMEM; |
145 | goto err_out; | |
146 | } | |
9803d413 | 147 | result = ima_store_template(entry, violation, inode, filename); |
3323eec9 | 148 | if (result < 0) |
a7ed7c60 | 149 | ima_free_template_entry(entry); |
3323eec9 MZ |
150 | err_out: |
151 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, | |
152 | op, cause, result, 0); | |
153 | } | |
154 | ||
155 | /** | |
d9d300cd | 156 | * ima_get_action - appraise & measure decision based on policy. |
3323eec9 MZ |
157 | * @inode: pointer to inode to measure |
158 | * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE) | |
4ad87a3d | 159 | * @func: caller identifier |
3323eec9 MZ |
160 | * |
161 | * The policy is defined in terms of keypairs: | |
2bb930ab | 162 | * subj=, obj=, type=, func=, mask=, fsmagic= |
3323eec9 | 163 | * subj,obj, and type: are LSM specific. |
2bb930ab DK |
164 | * func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK |
165 | * mask: contains the permission mask | |
3323eec9 MZ |
166 | * fsmagic: hex value |
167 | * | |
2fe5d6de MZ |
168 | * Returns IMA_MEASURE, IMA_APPRAISE mask. |
169 | * | |
170 | */ | |
4ad87a3d | 171 | int ima_get_action(struct inode *inode, int mask, enum ima_hooks func) |
3323eec9 | 172 | { |
e7c568e0 | 173 | int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE; |
2fe5d6de | 174 | |
fd5f4e90 | 175 | flags &= ima_policy_flag; |
2fe5d6de | 176 | |
4ad87a3d | 177 | return ima_match_policy(inode, func, mask, flags); |
2fe5d6de | 178 | } |
3323eec9 | 179 | |
3323eec9 MZ |
180 | /* |
181 | * ima_collect_measurement - collect file measurement | |
182 | * | |
183 | * Calculate the file hash, if it doesn't already exist, | |
184 | * storing the measurement and i_version in the iint. | |
185 | * | |
186 | * Must be called with iint->mutex held. | |
187 | * | |
188 | * Return 0 on success, error code otherwise | |
189 | */ | |
f381c272 | 190 | int ima_collect_measurement(struct integrity_iint_cache *iint, |
cf222217 MZ |
191 | struct file *file, void *buf, loff_t size, |
192 | enum hash_algo algo) | |
3323eec9 | 193 | { |
f9b2a735 | 194 | const char *audit_cause = "failed"; |
496ad9aa | 195 | struct inode *inode = file_inode(file); |
b583043e | 196 | const char *filename = file->f_path.dentry->d_name.name; |
2fe5d6de | 197 | int result = 0; |
a35c3fb6 DK |
198 | struct { |
199 | struct ima_digest_data hdr; | |
200 | char digest[IMA_MAX_DIGEST_SIZE]; | |
201 | } hash; | |
3323eec9 | 202 | |
2fe5d6de | 203 | if (!(iint->flags & IMA_COLLECTED)) { |
496ad9aa | 204 | u64 i_version = file_inode(file)->i_version; |
3323eec9 | 205 | |
f9b2a735 MZ |
206 | if (file->f_flags & O_DIRECT) { |
207 | audit_cause = "failed(directio)"; | |
208 | result = -EACCES; | |
209 | goto out; | |
210 | } | |
211 | ||
1525b06d | 212 | hash.hdr.algo = algo; |
d3634d0f | 213 | |
cf222217 MZ |
214 | result = (!buf) ? ima_calc_file_hash(file, &hash.hdr) : |
215 | ima_calc_buffer_hash(buf, size, &hash.hdr); | |
2fe5d6de | 216 | if (!result) { |
a35c3fb6 DK |
217 | int length = sizeof(hash.hdr) + hash.hdr.length; |
218 | void *tmpbuf = krealloc(iint->ima_hash, length, | |
219 | GFP_NOFS); | |
220 | if (tmpbuf) { | |
221 | iint->ima_hash = tmpbuf; | |
222 | memcpy(iint->ima_hash, &hash, length); | |
223 | iint->version = i_version; | |
224 | iint->flags |= IMA_COLLECTED; | |
225 | } else | |
226 | result = -ENOMEM; | |
2fe5d6de | 227 | } |
3323eec9 | 228 | } |
f9b2a735 | 229 | out: |
2fe5d6de MZ |
230 | if (result) |
231 | integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, | |
f9b2a735 | 232 | filename, "collect_data", audit_cause, |
2fe5d6de | 233 | result, 0); |
3323eec9 MZ |
234 | return result; |
235 | } | |
236 | ||
237 | /* | |
238 | * ima_store_measurement - store file measurement | |
239 | * | |
240 | * Create an "ima" template and then store the template by calling | |
241 | * ima_store_template. | |
242 | * | |
243 | * We only get here if the inode has not already been measured, | |
244 | * but the measurement could already exist: | |
2bb930ab | 245 | * - multiple copies of the same file on either the same or |
3323eec9 MZ |
246 | * different filesystems. |
247 | * - the inode was previously flushed as well as the iint info, | |
248 | * containing the hashing info. | |
249 | * | |
250 | * Must be called with iint->mutex held. | |
251 | */ | |
f381c272 | 252 | void ima_store_measurement(struct integrity_iint_cache *iint, |
bcbc9b0c MZ |
253 | struct file *file, const unsigned char *filename, |
254 | struct evm_ima_xattr_data *xattr_value, | |
255 | int xattr_len) | |
3323eec9 | 256 | { |
52a13284 MZ |
257 | static const char op[] = "add_template_measure"; |
258 | static const char audit_cause[] = "ENOMEM"; | |
3323eec9 | 259 | int result = -ENOMEM; |
496ad9aa | 260 | struct inode *inode = file_inode(file); |
3323eec9 | 261 | struct ima_template_entry *entry; |
8d94eb9b RS |
262 | struct ima_event_data event_data = {iint, file, filename, xattr_value, |
263 | xattr_len, NULL}; | |
3323eec9 MZ |
264 | int violation = 0; |
265 | ||
2fe5d6de MZ |
266 | if (iint->flags & IMA_MEASURED) |
267 | return; | |
268 | ||
23b57419 | 269 | result = ima_alloc_init_template(&event_data, &entry); |
7bc5f447 | 270 | if (result < 0) { |
3323eec9 MZ |
271 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, |
272 | op, audit_cause, result, 0); | |
273 | return; | |
274 | } | |
3323eec9 | 275 | |
9803d413 | 276 | result = ima_store_template(entry, violation, inode, filename); |
45fae749 | 277 | if (!result || result == -EEXIST) |
3323eec9 | 278 | iint->flags |= IMA_MEASURED; |
45fae749 | 279 | if (result < 0) |
a7ed7c60 | 280 | ima_free_template_entry(entry); |
3323eec9 | 281 | } |
e7c568e0 PM |
282 | |
283 | void ima_audit_measurement(struct integrity_iint_cache *iint, | |
284 | const unsigned char *filename) | |
285 | { | |
286 | struct audit_buffer *ab; | |
a35c3fb6 | 287 | char hash[(iint->ima_hash->length * 2) + 1]; |
5278aa52 MZ |
288 | const char *algo_name = hash_algo_name[iint->ima_hash->algo]; |
289 | char algo_hash[sizeof(hash) + strlen(algo_name) + 2]; | |
e7c568e0 PM |
290 | int i; |
291 | ||
292 | if (iint->flags & IMA_AUDITED) | |
293 | return; | |
294 | ||
a35c3fb6 DK |
295 | for (i = 0; i < iint->ima_hash->length; i++) |
296 | hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]); | |
e7c568e0 PM |
297 | hash[i * 2] = '\0'; |
298 | ||
299 | ab = audit_log_start(current->audit_context, GFP_KERNEL, | |
300 | AUDIT_INTEGRITY_RULE); | |
301 | if (!ab) | |
302 | return; | |
303 | ||
304 | audit_log_format(ab, "file="); | |
305 | audit_log_untrustedstring(ab, filename); | |
306 | audit_log_format(ab, " hash="); | |
5278aa52 MZ |
307 | snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash); |
308 | audit_log_untrustedstring(ab, algo_hash); | |
e7c568e0 PM |
309 | |
310 | audit_log_task_info(ab, current); | |
311 | audit_log_end(ab); | |
312 | ||
313 | iint->flags |= IMA_AUDITED; | |
314 | } | |
ea1046d4 | 315 | |
81cd8896 | 316 | const char *ima_d_path(const struct path *path, char **pathbuf) |
ea1046d4 DK |
317 | { |
318 | char *pathname = NULL; | |
319 | ||
456f5fd3 | 320 | *pathbuf = __getname(); |
ea1046d4 | 321 | if (*pathbuf) { |
17f4bad3 | 322 | pathname = d_absolute_path(path, *pathbuf, PATH_MAX); |
ea1046d4 | 323 | if (IS_ERR(pathname)) { |
456f5fd3 | 324 | __putname(*pathbuf); |
ea1046d4 DK |
325 | *pathbuf = NULL; |
326 | pathname = NULL; | |
327 | } | |
328 | } | |
61997c43 | 329 | return pathname ?: (const char *)path->dentry->d_name.name; |
ea1046d4 | 330 | } |