ima: Do not free 'entry' before it is initialized
[deliverable/linux.git] / security / integrity / ima / ima_api.c
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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
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12 * Implements must_appraise_or_measure, collect_measurement,
13 * appraise_measurement, store_measurement and store_template.
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14 */
15#include <linux/module.h>
5a0e3ad6 16#include <linux/slab.h>
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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
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24/*
25 * ima_alloc_init_template - create and initialize a new template entry
26 */
27int ima_alloc_init_template(struct integrity_iint_cache *iint,
28 struct file *file, const unsigned char *filename,
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29 struct evm_ima_xattr_data *xattr_value,
30 int xattr_len, struct ima_template_entry **entry)
7bc5f447 31{
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32 struct ima_template_desc *template_desc = ima_template_desc_current();
33 int i, result = 0;
7bc5f447 34
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35 *entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
36 sizeof(struct ima_field_data), GFP_NOFS);
37 if (!*entry)
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38 return -ENOMEM;
39
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40 for (i = 0; i < template_desc->num_fields; i++) {
41 struct ima_template_field *field = template_desc->fields[i];
42 u32 len;
7bc5f447 43
a71dc65d 44 result = field->field_init(iint, file, filename,
bcbc9b0c 45 xattr_value, xattr_len,
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46 &((*entry)->template_data[i]));
47 if (result != 0)
48 goto out;
7bc5f447 49
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50 len = (*entry)->template_data[i].len;
51 (*entry)->template_data_len += sizeof(len);
52 (*entry)->template_data_len += len;
53 }
54 (*entry)->template_desc = template_desc;
7bc5f447 55 return 0;
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56out:
57 kfree(*entry);
58 *entry = NULL;
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59 return result;
60}
61
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62/*
63 * ima_store_template - store ima template measurements
64 *
65 * Calculate the hash of a template entry, add the template entry
66 * to an ordered list of measurement entries maintained inside the kernel,
67 * and also update the aggregate integrity value (maintained inside the
68 * configured TPM PCR) over the hashes of the current list of measurement
69 * entries.
70 *
71 * Applications retrieve the current kernel-held measurement list through
72 * the securityfs entries in /sys/kernel/security/ima. The signed aggregate
73 * TPM PCR (called quote) can be retrieved using a TPM user space library
74 * and is used to validate the measurement list.
75 *
76 * Returns 0 on success, error code otherwise
77 */
78int ima_store_template(struct ima_template_entry *entry,
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79 int violation, struct inode *inode,
80 const unsigned char *filename)
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81{
82 const char *op = "add_template_measure";
83 const char *audit_cause = "hashing_error";
a71dc65d 84 char *template_name = entry->template_desc->name;
3323eec9 85 int result;
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86 struct {
87 struct ima_digest_data hdr;
140d8022 88 char digest[TPM_DIGEST_SIZE];
a35c3fb6 89 } hash;
3323eec9 90
3323eec9 91 if (!violation) {
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92 int num_fields = entry->template_desc->num_fields;
93
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94 /* this function uses default algo */
95 hash.hdr.algo = HASH_ALGO_SHA1;
a71dc65d 96 result = ima_calc_field_array_hash(&entry->template_data[0],
b6f8f16f 97 entry->template_desc,
a71dc65d 98 num_fields, &hash.hdr);
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99 if (result < 0) {
100 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
a71dc65d 101 template_name, op,
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102 audit_cause, result, 0);
103 return result;
104 }
a35c3fb6 105 memcpy(entry->digest, hash.hdr.digest, hash.hdr.length);
3323eec9 106 }
9803d413 107 result = ima_add_template_entry(entry, violation, op, inode, filename);
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108 return result;
109}
110
111/*
112 * ima_add_violation - add violation to measurement list.
113 *
114 * Violations are flagged in the measurement list with zero hash values.
115 * By extending the PCR with 0xFF's instead of with zeroes, the PCR
116 * value is invalidated.
117 */
7d802a22 118void ima_add_violation(struct file *file, const unsigned char *filename,
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119 const char *op, const char *cause)
120{
121 struct ima_template_entry *entry;
7d802a22 122 struct inode *inode = file->f_dentry->d_inode;
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123 int violation = 1;
124 int result;
125
126 /* can overflow, only indicator */
127 atomic_long_inc(&ima_htable.violations);
128
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129 result = ima_alloc_init_template(NULL, file, filename,
130 NULL, 0, &entry);
7bc5f447 131 if (result < 0) {
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132 result = -ENOMEM;
133 goto err_out;
134 }
9803d413 135 result = ima_store_template(entry, violation, inode, filename);
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136 if (result < 0)
137 kfree(entry);
138err_out:
139 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
140 op, cause, result, 0);
141}
142
143/**
d9d300cd 144 * ima_get_action - appraise & measure decision based on policy.
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145 * @inode: pointer to inode to measure
146 * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
16cac49f 147 * @function: calling function (FILE_CHECK, BPRM_CHECK, MMAP_CHECK, MODULE_CHECK)
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148 *
149 * The policy is defined in terms of keypairs:
150 * subj=, obj=, type=, func=, mask=, fsmagic=
151 * subj,obj, and type: are LSM specific.
16cac49f 152 * func: FILE_CHECK | BPRM_CHECK | MMAP_CHECK | MODULE_CHECK
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153 * mask: contains the permission mask
154 * fsmagic: hex value
155 *
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156 * Returns IMA_MEASURE, IMA_APPRAISE mask.
157 *
158 */
d9d300cd 159int ima_get_action(struct inode *inode, int mask, int function)
3323eec9 160{
e7c568e0 161 int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE;
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162
163 if (!ima_appraise)
164 flags &= ~IMA_APPRAISE;
165
166 return ima_match_policy(inode, function, mask, flags);
167}
3323eec9 168
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169int ima_must_measure(struct inode *inode, int mask, int function)
170{
171 return ima_match_policy(inode, function, mask, IMA_MEASURE);
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172}
173
174/*
175 * ima_collect_measurement - collect file measurement
176 *
177 * Calculate the file hash, if it doesn't already exist,
178 * storing the measurement and i_version in the iint.
179 *
180 * Must be called with iint->mutex held.
181 *
182 * Return 0 on success, error code otherwise
183 */
f381c272 184int ima_collect_measurement(struct integrity_iint_cache *iint,
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185 struct file *file,
186 struct evm_ima_xattr_data **xattr_value,
187 int *xattr_len)
3323eec9 188{
496ad9aa 189 struct inode *inode = file_inode(file);
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190 const char *filename = file->f_dentry->d_name.name;
191 int result = 0;
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192 struct {
193 struct ima_digest_data hdr;
194 char digest[IMA_MAX_DIGEST_SIZE];
195 } hash;
3323eec9 196
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197 if (xattr_value)
198 *xattr_len = ima_read_xattr(file->f_dentry, xattr_value);
199
2fe5d6de 200 if (!(iint->flags & IMA_COLLECTED)) {
496ad9aa 201 u64 i_version = file_inode(file)->i_version;
3323eec9 202
c7c8bb23 203 /* use default hash algorithm */
a35c3fb6 204 hash.hdr.algo = ima_hash_algo;
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205
206 if (xattr_value)
a35c3fb6 207 ima_get_hash_algo(*xattr_value, *xattr_len, &hash.hdr);
d3634d0f 208
a35c3fb6 209 result = ima_calc_file_hash(file, &hash.hdr);
2fe5d6de 210 if (!result) {
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211 int length = sizeof(hash.hdr) + hash.hdr.length;
212 void *tmpbuf = krealloc(iint->ima_hash, length,
213 GFP_NOFS);
214 if (tmpbuf) {
215 iint->ima_hash = tmpbuf;
216 memcpy(iint->ima_hash, &hash, length);
217 iint->version = i_version;
218 iint->flags |= IMA_COLLECTED;
219 } else
220 result = -ENOMEM;
2fe5d6de 221 }
3323eec9 222 }
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223 if (result)
224 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
225 filename, "collect_data", "failed",
226 result, 0);
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227 return result;
228}
229
230/*
231 * ima_store_measurement - store file measurement
232 *
233 * Create an "ima" template and then store the template by calling
234 * ima_store_template.
235 *
236 * We only get here if the inode has not already been measured,
237 * but the measurement could already exist:
238 * - multiple copies of the same file on either the same or
239 * different filesystems.
240 * - the inode was previously flushed as well as the iint info,
241 * containing the hashing info.
242 *
243 * Must be called with iint->mutex held.
244 */
f381c272 245void ima_store_measurement(struct integrity_iint_cache *iint,
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246 struct file *file, const unsigned char *filename,
247 struct evm_ima_xattr_data *xattr_value,
248 int xattr_len)
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249{
250 const char *op = "add_template_measure";
251 const char *audit_cause = "ENOMEM";
252 int result = -ENOMEM;
496ad9aa 253 struct inode *inode = file_inode(file);
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254 struct ima_template_entry *entry;
255 int violation = 0;
256
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257 if (iint->flags & IMA_MEASURED)
258 return;
259
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260 result = ima_alloc_init_template(iint, file, filename,
261 xattr_value, xattr_len, &entry);
7bc5f447 262 if (result < 0) {
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263 integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
264 op, audit_cause, result, 0);
265 return;
266 }
3323eec9 267
9803d413 268 result = ima_store_template(entry, violation, inode, filename);
45fae749 269 if (!result || result == -EEXIST)
3323eec9 270 iint->flags |= IMA_MEASURED;
45fae749 271 if (result < 0)
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272 kfree(entry);
273}
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274
275void ima_audit_measurement(struct integrity_iint_cache *iint,
276 const unsigned char *filename)
277{
278 struct audit_buffer *ab;
a35c3fb6 279 char hash[(iint->ima_hash->length * 2) + 1];
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280 const char *algo_name = hash_algo_name[iint->ima_hash->algo];
281 char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
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282 int i;
283
284 if (iint->flags & IMA_AUDITED)
285 return;
286
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287 for (i = 0; i < iint->ima_hash->length; i++)
288 hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
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289 hash[i * 2] = '\0';
290
291 ab = audit_log_start(current->audit_context, GFP_KERNEL,
292 AUDIT_INTEGRITY_RULE);
293 if (!ab)
294 return;
295
296 audit_log_format(ab, "file=");
297 audit_log_untrustedstring(ab, filename);
298 audit_log_format(ab, " hash=");
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299 snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
300 audit_log_untrustedstring(ab, algo_hash);
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301
302 audit_log_task_info(ab, current);
303 audit_log_end(ab);
304
305 iint->flags |= IMA_AUDITED;
306}
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307
308const char *ima_d_path(struct path *path, char **pathbuf)
309{
310 char *pathname = NULL;
311
312 /* We will allow 11 spaces for ' (deleted)' to be appended */
313 *pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
314 if (*pathbuf) {
315 pathname = d_path(path, *pathbuf, PATH_MAX + 11);
316 if (IS_ERR(pathname)) {
317 kfree(*pathbuf);
318 *pathbuf = NULL;
319 pathname = NULL;
320 }
321 }
322 return pathname;
323}
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