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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> | |
ea593993 | 21 | #include <crypto/hash_info.h> |
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 | */ | |
40 | int ima_alloc_init_template(struct integrity_iint_cache *iint, | |
41 | struct file *file, const unsigned char *filename, | |
bcbc9b0c MZ |
42 | struct evm_ima_xattr_data *xattr_value, |
43 | int xattr_len, struct ima_template_entry **entry) | |
7bc5f447 | 44 | { |
a71dc65d RS |
45 | struct ima_template_desc *template_desc = ima_template_desc_current(); |
46 | int i, result = 0; | |
7bc5f447 | 47 | |
a71dc65d RS |
48 | *entry = kzalloc(sizeof(**entry) + template_desc->num_fields * |
49 | sizeof(struct ima_field_data), GFP_NOFS); | |
50 | if (!*entry) | |
7bc5f447 RS |
51 | return -ENOMEM; |
52 | ||
a7ed7c60 | 53 | (*entry)->template_desc = template_desc; |
a71dc65d RS |
54 | for (i = 0; i < template_desc->num_fields; i++) { |
55 | struct ima_template_field *field = template_desc->fields[i]; | |
56 | u32 len; | |
7bc5f447 | 57 | |
a71dc65d | 58 | result = field->field_init(iint, file, filename, |
bcbc9b0c | 59 | xattr_value, xattr_len, |
a71dc65d RS |
60 | &((*entry)->template_data[i])); |
61 | if (result != 0) | |
62 | goto out; | |
7bc5f447 | 63 | |
a71dc65d RS |
64 | len = (*entry)->template_data[i].len; |
65 | (*entry)->template_data_len += sizeof(len); | |
66 | (*entry)->template_data_len += len; | |
67 | } | |
7bc5f447 | 68 | return 0; |
a71dc65d | 69 | out: |
a7ed7c60 | 70 | ima_free_template_entry(*entry); |
a71dc65d | 71 | *entry = NULL; |
7bc5f447 RS |
72 | return result; |
73 | } | |
74 | ||
3323eec9 MZ |
75 | /* |
76 | * ima_store_template - store ima template measurements | |
77 | * | |
78 | * Calculate the hash of a template entry, add the template entry | |
79 | * to an ordered list of measurement entries maintained inside the kernel, | |
80 | * and also update the aggregate integrity value (maintained inside the | |
81 | * configured TPM PCR) over the hashes of the current list of measurement | |
82 | * entries. | |
83 | * | |
84 | * Applications retrieve the current kernel-held measurement list through | |
85 | * the securityfs entries in /sys/kernel/security/ima. The signed aggregate | |
86 | * TPM PCR (called quote) can be retrieved using a TPM user space library | |
87 | * and is used to validate the measurement list. | |
88 | * | |
89 | * Returns 0 on success, error code otherwise | |
90 | */ | |
91 | int ima_store_template(struct ima_template_entry *entry, | |
9803d413 RS |
92 | int violation, struct inode *inode, |
93 | const unsigned char *filename) | |
3323eec9 | 94 | { |
52a13284 MZ |
95 | static const char op[] = "add_template_measure"; |
96 | static const char audit_cause[] = "hashing_error"; | |
a71dc65d | 97 | char *template_name = entry->template_desc->name; |
3323eec9 | 98 | int result; |
a35c3fb6 DK |
99 | struct { |
100 | struct ima_digest_data hdr; | |
140d8022 | 101 | char digest[TPM_DIGEST_SIZE]; |
a35c3fb6 | 102 | } hash; |
3323eec9 | 103 | |
3323eec9 | 104 | if (!violation) { |
a71dc65d RS |
105 | int num_fields = entry->template_desc->num_fields; |
106 | ||
ea593993 DK |
107 | /* this function uses default algo */ |
108 | hash.hdr.algo = HASH_ALGO_SHA1; | |
a71dc65d | 109 | result = ima_calc_field_array_hash(&entry->template_data[0], |
b6f8f16f | 110 | entry->template_desc, |
a71dc65d | 111 | num_fields, &hash.hdr); |
3323eec9 MZ |
112 | if (result < 0) { |
113 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, | |
a71dc65d | 114 | template_name, op, |
3323eec9 MZ |
115 | audit_cause, result, 0); |
116 | return result; | |
117 | } | |
a35c3fb6 | 118 | memcpy(entry->digest, hash.hdr.digest, hash.hdr.length); |
3323eec9 | 119 | } |
9803d413 | 120 | result = ima_add_template_entry(entry, violation, op, inode, filename); |
3323eec9 MZ |
121 | return result; |
122 | } | |
123 | ||
124 | /* | |
125 | * ima_add_violation - add violation to measurement list. | |
126 | * | |
127 | * Violations are flagged in the measurement list with zero hash values. | |
128 | * By extending the PCR with 0xFF's instead of with zeroes, the PCR | |
129 | * value is invalidated. | |
130 | */ | |
7d802a22 | 131 | void ima_add_violation(struct file *file, const unsigned char *filename, |
3323eec9 MZ |
132 | const char *op, const char *cause) |
133 | { | |
134 | struct ima_template_entry *entry; | |
31d4b761 | 135 | struct inode *inode = file_inode(file); |
3323eec9 MZ |
136 | int violation = 1; |
137 | int result; | |
138 | ||
139 | /* can overflow, only indicator */ | |
140 | atomic_long_inc(&ima_htable.violations); | |
141 | ||
bcbc9b0c MZ |
142 | result = ima_alloc_init_template(NULL, file, filename, |
143 | NULL, 0, &entry); | |
7bc5f447 | 144 | if (result < 0) { |
3323eec9 MZ |
145 | result = -ENOMEM; |
146 | goto err_out; | |
147 | } | |
9803d413 | 148 | result = ima_store_template(entry, violation, inode, filename); |
3323eec9 | 149 | if (result < 0) |
a7ed7c60 | 150 | ima_free_template_entry(entry); |
3323eec9 MZ |
151 | err_out: |
152 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, | |
153 | op, cause, result, 0); | |
154 | } | |
155 | ||
156 | /** | |
d9d300cd | 157 | * ima_get_action - appraise & measure decision based on policy. |
3323eec9 MZ |
158 | * @inode: pointer to inode to measure |
159 | * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE) | |
16cac49f | 160 | * @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK) |
3323eec9 MZ |
161 | * |
162 | * The policy is defined in terms of keypairs: | |
2bb930ab | 163 | * subj=, obj=, type=, func=, mask=, fsmagic= |
3323eec9 | 164 | * subj,obj, and type: are LSM specific. |
2bb930ab DK |
165 | * func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK |
166 | * mask: contains the permission mask | |
3323eec9 MZ |
167 | * fsmagic: hex value |
168 | * | |
2fe5d6de MZ |
169 | * Returns IMA_MEASURE, IMA_APPRAISE mask. |
170 | * | |
171 | */ | |
d9d300cd | 172 | int ima_get_action(struct inode *inode, int mask, int function) |
3323eec9 | 173 | { |
e7c568e0 | 174 | int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE; |
2fe5d6de MZ |
175 | |
176 | if (!ima_appraise) | |
177 | flags &= ~IMA_APPRAISE; | |
178 | ||
179 | return ima_match_policy(inode, function, mask, flags); | |
180 | } | |
3323eec9 | 181 | |
2fe5d6de MZ |
182 | int ima_must_measure(struct inode *inode, int mask, int function) |
183 | { | |
184 | return ima_match_policy(inode, function, mask, IMA_MEASURE); | |
3323eec9 MZ |
185 | } |
186 | ||
187 | /* | |
188 | * ima_collect_measurement - collect file measurement | |
189 | * | |
190 | * Calculate the file hash, if it doesn't already exist, | |
191 | * storing the measurement and i_version in the iint. | |
192 | * | |
193 | * Must be called with iint->mutex held. | |
194 | * | |
195 | * Return 0 on success, error code otherwise | |
196 | */ | |
f381c272 | 197 | int ima_collect_measurement(struct integrity_iint_cache *iint, |
d3634d0f DK |
198 | struct file *file, |
199 | struct evm_ima_xattr_data **xattr_value, | |
200 | int *xattr_len) | |
3323eec9 | 201 | { |
496ad9aa | 202 | struct inode *inode = file_inode(file); |
2fe5d6de MZ |
203 | const char *filename = file->f_dentry->d_name.name; |
204 | int result = 0; | |
a35c3fb6 DK |
205 | struct { |
206 | struct ima_digest_data hdr; | |
207 | char digest[IMA_MAX_DIGEST_SIZE]; | |
208 | } hash; | |
3323eec9 | 209 | |
d3634d0f DK |
210 | if (xattr_value) |
211 | *xattr_len = ima_read_xattr(file->f_dentry, xattr_value); | |
212 | ||
2fe5d6de | 213 | if (!(iint->flags & IMA_COLLECTED)) { |
496ad9aa | 214 | u64 i_version = file_inode(file)->i_version; |
3323eec9 | 215 | |
c7c8bb23 | 216 | /* use default hash algorithm */ |
a35c3fb6 | 217 | hash.hdr.algo = ima_hash_algo; |
d3634d0f DK |
218 | |
219 | if (xattr_value) | |
a35c3fb6 | 220 | ima_get_hash_algo(*xattr_value, *xattr_len, &hash.hdr); |
d3634d0f | 221 | |
a35c3fb6 | 222 | result = ima_calc_file_hash(file, &hash.hdr); |
2fe5d6de | 223 | if (!result) { |
a35c3fb6 DK |
224 | int length = sizeof(hash.hdr) + hash.hdr.length; |
225 | void *tmpbuf = krealloc(iint->ima_hash, length, | |
226 | GFP_NOFS); | |
227 | if (tmpbuf) { | |
228 | iint->ima_hash = tmpbuf; | |
229 | memcpy(iint->ima_hash, &hash, length); | |
230 | iint->version = i_version; | |
231 | iint->flags |= IMA_COLLECTED; | |
232 | } else | |
233 | result = -ENOMEM; | |
2fe5d6de | 234 | } |
3323eec9 | 235 | } |
2fe5d6de MZ |
236 | if (result) |
237 | integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, | |
238 | filename, "collect_data", "failed", | |
239 | result, 0); | |
3323eec9 MZ |
240 | return result; |
241 | } | |
242 | ||
243 | /* | |
244 | * ima_store_measurement - store file measurement | |
245 | * | |
246 | * Create an "ima" template and then store the template by calling | |
247 | * ima_store_template. | |
248 | * | |
249 | * We only get here if the inode has not already been measured, | |
250 | * but the measurement could already exist: | |
2bb930ab | 251 | * - multiple copies of the same file on either the same or |
3323eec9 MZ |
252 | * different filesystems. |
253 | * - the inode was previously flushed as well as the iint info, | |
254 | * containing the hashing info. | |
255 | * | |
256 | * Must be called with iint->mutex held. | |
257 | */ | |
f381c272 | 258 | void ima_store_measurement(struct integrity_iint_cache *iint, |
bcbc9b0c MZ |
259 | struct file *file, const unsigned char *filename, |
260 | struct evm_ima_xattr_data *xattr_value, | |
261 | int xattr_len) | |
3323eec9 | 262 | { |
52a13284 MZ |
263 | static const char op[] = "add_template_measure"; |
264 | static const char audit_cause[] = "ENOMEM"; | |
3323eec9 | 265 | int result = -ENOMEM; |
496ad9aa | 266 | struct inode *inode = file_inode(file); |
3323eec9 MZ |
267 | struct ima_template_entry *entry; |
268 | int violation = 0; | |
269 | ||
2fe5d6de MZ |
270 | if (iint->flags & IMA_MEASURED) |
271 | return; | |
272 | ||
bcbc9b0c MZ |
273 | result = ima_alloc_init_template(iint, file, filename, |
274 | xattr_value, xattr_len, &entry); | |
7bc5f447 | 275 | if (result < 0) { |
3323eec9 MZ |
276 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, |
277 | op, audit_cause, result, 0); | |
278 | return; | |
279 | } | |
3323eec9 | 280 | |
9803d413 | 281 | result = ima_store_template(entry, violation, inode, filename); |
45fae749 | 282 | if (!result || result == -EEXIST) |
3323eec9 | 283 | iint->flags |= IMA_MEASURED; |
45fae749 | 284 | if (result < 0) |
a7ed7c60 | 285 | ima_free_template_entry(entry); |
3323eec9 | 286 | } |
e7c568e0 PM |
287 | |
288 | void ima_audit_measurement(struct integrity_iint_cache *iint, | |
289 | const unsigned char *filename) | |
290 | { | |
291 | struct audit_buffer *ab; | |
a35c3fb6 | 292 | char hash[(iint->ima_hash->length * 2) + 1]; |
5278aa52 MZ |
293 | const char *algo_name = hash_algo_name[iint->ima_hash->algo]; |
294 | char algo_hash[sizeof(hash) + strlen(algo_name) + 2]; | |
e7c568e0 PM |
295 | int i; |
296 | ||
297 | if (iint->flags & IMA_AUDITED) | |
298 | return; | |
299 | ||
a35c3fb6 DK |
300 | for (i = 0; i < iint->ima_hash->length; i++) |
301 | hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]); | |
e7c568e0 PM |
302 | hash[i * 2] = '\0'; |
303 | ||
304 | ab = audit_log_start(current->audit_context, GFP_KERNEL, | |
305 | AUDIT_INTEGRITY_RULE); | |
306 | if (!ab) | |
307 | return; | |
308 | ||
309 | audit_log_format(ab, "file="); | |
310 | audit_log_untrustedstring(ab, filename); | |
311 | audit_log_format(ab, " hash="); | |
5278aa52 MZ |
312 | snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash); |
313 | audit_log_untrustedstring(ab, algo_hash); | |
e7c568e0 PM |
314 | |
315 | audit_log_task_info(ab, current); | |
316 | audit_log_end(ab); | |
317 | ||
318 | iint->flags |= IMA_AUDITED; | |
319 | } | |
ea1046d4 DK |
320 | |
321 | const char *ima_d_path(struct path *path, char **pathbuf) | |
322 | { | |
323 | char *pathname = NULL; | |
324 | ||
325 | /* We will allow 11 spaces for ' (deleted)' to be appended */ | |
326 | *pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL); | |
327 | if (*pathbuf) { | |
328 | pathname = d_path(path, *pathbuf, PATH_MAX + 11); | |
329 | if (IS_ERR(pathname)) { | |
330 | kfree(*pathbuf); | |
331 | *pathbuf = NULL; | |
332 | pathname = NULL; | |
333 | } | |
334 | } | |
61997c43 | 335 | return pathname ?: (const char *)path->dentry->d_name.name; |
ea1046d4 | 336 | } |