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3323eec9 MZ |
1 | /* |
2 | * Copyright (C) 2005,2006,2007,2008 IBM Corporation | |
3 | * | |
4 | * Authors: | |
5 | * Reiner Sailer <sailer@watson.ibm.com> | |
6 | * Serge Hallyn <serue@us.ibm.com> | |
7 | * Kylene Hall <kylene@us.ibm.com> | |
8 | * Mimi Zohar <zohar@us.ibm.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License as | |
12 | * published by the Free Software Foundation, version 2 of the | |
13 | * License. | |
14 | * | |
15 | * File: ima_main.c | |
e0d5bd2a | 16 | * implements the IMA hooks: ima_bprm_check, ima_file_mmap, |
9bbb6cad | 17 | * and ima_file_check. |
3323eec9 MZ |
18 | */ |
19 | #include <linux/module.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/binfmts.h> | |
22 | #include <linux/mount.h> | |
23 | #include <linux/mman.h> | |
5a0e3ad6 | 24 | #include <linux/slab.h> |
3323eec9 MZ |
25 | |
26 | #include "ima.h" | |
27 | ||
28 | int ima_initialized; | |
29 | ||
30 | char *ima_hash = "sha1"; | |
31 | static int __init hash_setup(char *str) | |
32 | { | |
07ff7a0b MZ |
33 | if (strncmp(str, "md5", 3) == 0) |
34 | ima_hash = "md5"; | |
3323eec9 MZ |
35 | return 1; |
36 | } | |
37 | __setup("ima_hash=", hash_setup); | |
38 | ||
8eb988c7 | 39 | /* |
890275b5 | 40 | * ima_rdwr_violation_check |
8eb988c7 | 41 | * |
890275b5 | 42 | * Only invalidate the PCR for measured files: |
8eb988c7 MZ |
43 | * - Opening a file for write when already open for read, |
44 | * results in a time of measure, time of use (ToMToU) error. | |
45 | * - Opening a file for read when already open for write, | |
46 | * could result in a file measurement error. | |
47 | * | |
48 | */ | |
890275b5 | 49 | static void ima_rdwr_violation_check(struct file *file) |
8eb988c7 MZ |
50 | { |
51 | struct dentry *dentry = file->f_path.dentry; | |
52 | struct inode *inode = dentry->d_inode; | |
53 | fmode_t mode = file->f_mode; | |
8eb988c7 | 54 | int rc; |
ad16ad00 | 55 | bool send_tomtou = false, send_writers = false; |
8eb988c7 | 56 | |
890275b5 | 57 | if (!S_ISREG(inode->i_mode) || !ima_initialized) |
8eb988c7 | 58 | return; |
a178d202 | 59 | |
890275b5 | 60 | mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */ |
ad16ad00 | 61 | |
8eb988c7 | 62 | if (mode & FMODE_WRITE) { |
a68a27b6 | 63 | if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) |
ad16ad00 | 64 | send_tomtou = true; |
8eb988c7 MZ |
65 | goto out; |
66 | } | |
ad16ad00 | 67 | |
1adace9b | 68 | rc = ima_must_measure(inode, MAY_READ, FILE_CHECK); |
bade72d6 EP |
69 | if (rc < 0) |
70 | goto out; | |
71 | ||
ad16ad00 EP |
72 | if (atomic_read(&inode->i_writecount) > 0) |
73 | send_writers = true; | |
8eb988c7 | 74 | out: |
890275b5 | 75 | mutex_unlock(&inode->i_mutex); |
ad16ad00 EP |
76 | |
77 | if (send_tomtou) | |
78 | ima_add_violation(inode, dentry->d_name.name, "invalid_pcr", | |
79 | "ToMToU"); | |
80 | if (send_writers) | |
81 | ima_add_violation(inode, dentry->d_name.name, "invalid_pcr", | |
82 | "open_writers"); | |
8eb988c7 MZ |
83 | } |
84 | ||
f381c272 | 85 | static void ima_check_last_writer(struct integrity_iint_cache *iint, |
bc7d2a3e EP |
86 | struct inode *inode, |
87 | struct file *file) | |
88 | { | |
4b2a2c67 | 89 | fmode_t mode = file->f_mode; |
bc7d2a3e | 90 | |
854fdd55 | 91 | mutex_lock(&iint->mutex); |
bc7d2a3e EP |
92 | if (mode & FMODE_WRITE && |
93 | atomic_read(&inode->i_writecount) == 1 && | |
94 | iint->version != inode->i_version) | |
95 | iint->flags &= ~IMA_MEASURED; | |
bc7d2a3e | 96 | mutex_unlock(&iint->mutex); |
bc7d2a3e EP |
97 | } |
98 | ||
3323eec9 MZ |
99 | /** |
100 | * ima_file_free - called on __fput() | |
101 | * @file: pointer to file structure being freed | |
102 | * | |
890275b5 | 103 | * Flag files that changed, based on i_version |
3323eec9 MZ |
104 | */ |
105 | void ima_file_free(struct file *file) | |
106 | { | |
107 | struct inode *inode = file->f_dentry->d_inode; | |
f381c272 | 108 | struct integrity_iint_cache *iint; |
3323eec9 | 109 | |
e950598d | 110 | if (!iint_initialized || !S_ISREG(inode->i_mode)) |
3323eec9 | 111 | return; |
196f5181 | 112 | |
f381c272 | 113 | iint = integrity_iint_find(inode); |
854fdd55 MZ |
114 | if (!iint) |
115 | return; | |
3323eec9 | 116 | |
854fdd55 | 117 | ima_check_last_writer(iint, inode, file); |
3323eec9 MZ |
118 | } |
119 | ||
3323eec9 MZ |
120 | static int process_measurement(struct file *file, const unsigned char *filename, |
121 | int mask, int function) | |
122 | { | |
123 | struct inode *inode = file->f_dentry->d_inode; | |
f381c272 | 124 | struct integrity_iint_cache *iint; |
e950598d | 125 | int rc = 0; |
3323eec9 MZ |
126 | |
127 | if (!ima_initialized || !S_ISREG(inode->i_mode)) | |
128 | return 0; | |
bc7d2a3e | 129 | |
1adace9b | 130 | rc = ima_must_measure(inode, mask, function); |
bc7d2a3e EP |
131 | if (rc != 0) |
132 | return rc; | |
133 | retry: | |
f381c272 | 134 | iint = integrity_iint_find(inode); |
bc7d2a3e | 135 | if (!iint) { |
f381c272 | 136 | rc = integrity_inode_alloc(inode); |
bc7d2a3e EP |
137 | if (!rc || rc == -EEXIST) |
138 | goto retry; | |
139 | return rc; | |
140 | } | |
3323eec9 MZ |
141 | |
142 | mutex_lock(&iint->mutex); | |
bc7d2a3e | 143 | |
1adace9b | 144 | rc = iint->flags & IMA_MEASURED ? 1 : 0; |
3323eec9 MZ |
145 | if (rc != 0) |
146 | goto out; | |
147 | ||
148 | rc = ima_collect_measurement(iint, file); | |
149 | if (!rc) | |
150 | ima_store_measurement(iint, file, filename); | |
151 | out: | |
152 | mutex_unlock(&iint->mutex); | |
3323eec9 MZ |
153 | return rc; |
154 | } | |
155 | ||
156 | /** | |
157 | * ima_file_mmap - based on policy, collect/store measurement. | |
158 | * @file: pointer to the file to be measured (May be NULL) | |
159 | * @prot: contains the protection that will be applied by the kernel. | |
160 | * | |
161 | * Measure files being mmapped executable based on the ima_must_measure() | |
162 | * policy decision. | |
163 | * | |
164 | * Return 0 on success, an error code on failure. | |
165 | * (Based on the results of appraise_measurement().) | |
166 | */ | |
167 | int ima_file_mmap(struct file *file, unsigned long prot) | |
168 | { | |
169 | int rc; | |
170 | ||
171 | if (!file) | |
172 | return 0; | |
173 | if (prot & PROT_EXEC) | |
174 | rc = process_measurement(file, file->f_dentry->d_name.name, | |
175 | MAY_EXEC, FILE_MMAP); | |
176 | return 0; | |
177 | } | |
178 | ||
179 | /** | |
180 | * ima_bprm_check - based on policy, collect/store measurement. | |
181 | * @bprm: contains the linux_binprm structure | |
182 | * | |
183 | * The OS protects against an executable file, already open for write, | |
184 | * from being executed in deny_write_access() and an executable file, | |
185 | * already open for execute, from being modified in get_write_access(). | |
186 | * So we can be certain that what we verify and measure here is actually | |
187 | * what is being executed. | |
188 | * | |
189 | * Return 0 on success, an error code on failure. | |
190 | * (Based on the results of appraise_measurement().) | |
191 | */ | |
192 | int ima_bprm_check(struct linux_binprm *bprm) | |
193 | { | |
194 | int rc; | |
195 | ||
196 | rc = process_measurement(bprm->file, bprm->filename, | |
197 | MAY_EXEC, BPRM_CHECK); | |
198 | return 0; | |
199 | } | |
200 | ||
8eb988c7 MZ |
201 | /** |
202 | * ima_path_check - based on policy, collect/store measurement. | |
203 | * @file: pointer to the file to be measured | |
204 | * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE | |
205 | * | |
206 | * Measure files based on the ima_must_measure() policy decision. | |
207 | * | |
208 | * Always return 0 and audit dentry_open failures. | |
209 | * (Return code will be based upon measurement appraisal.) | |
210 | */ | |
9bbb6cad | 211 | int ima_file_check(struct file *file, int mask) |
8eb988c7 MZ |
212 | { |
213 | int rc; | |
214 | ||
890275b5 | 215 | ima_rdwr_violation_check(file); |
8eb988c7 MZ |
216 | rc = process_measurement(file, file->f_dentry->d_name.name, |
217 | mask & (MAY_READ | MAY_WRITE | MAY_EXEC), | |
1e93d005 | 218 | FILE_CHECK); |
8eb988c7 MZ |
219 | return 0; |
220 | } | |
9bbb6cad | 221 | EXPORT_SYMBOL_GPL(ima_file_check); |
8eb988c7 | 222 | |
3323eec9 MZ |
223 | static int __init init_ima(void) |
224 | { | |
225 | int error; | |
226 | ||
3323eec9 MZ |
227 | error = ima_init(); |
228 | ima_initialized = 1; | |
229 | return error; | |
230 | } | |
231 | ||
bab73937 MZ |
232 | static void __exit cleanup_ima(void) |
233 | { | |
234 | ima_cleanup(); | |
235 | } | |
236 | ||
3323eec9 MZ |
237 | late_initcall(init_ima); /* Start IMA after the TPM is available */ |
238 | ||
239 | MODULE_DESCRIPTION("Integrity Measurement Architecture"); | |
240 | MODULE_LICENSE("GPL"); |