Commit | Line | Data |
---|---|---|
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 | |
12 | * Implements must_measure, collect_measurement, store_measurement, | |
13 | * and store_template. | |
14 | */ | |
15 | #include <linux/module.h> | |
5a0e3ad6 | 16 | #include <linux/slab.h> |
3323eec9 MZ |
17 | |
18 | #include "ima.h" | |
523979ad | 19 | static const char *IMA_TEMPLATE_NAME = "ima"; |
3323eec9 MZ |
20 | |
21 | /* | |
22 | * ima_store_template - store ima template measurements | |
23 | * | |
24 | * Calculate the hash of a template entry, add the template entry | |
25 | * to an ordered list of measurement entries maintained inside the kernel, | |
26 | * and also update the aggregate integrity value (maintained inside the | |
27 | * configured TPM PCR) over the hashes of the current list of measurement | |
28 | * entries. | |
29 | * | |
30 | * Applications retrieve the current kernel-held measurement list through | |
31 | * the securityfs entries in /sys/kernel/security/ima. The signed aggregate | |
32 | * TPM PCR (called quote) can be retrieved using a TPM user space library | |
33 | * and is used to validate the measurement list. | |
34 | * | |
35 | * Returns 0 on success, error code otherwise | |
36 | */ | |
37 | int ima_store_template(struct ima_template_entry *entry, | |
38 | int violation, struct inode *inode) | |
39 | { | |
40 | const char *op = "add_template_measure"; | |
41 | const char *audit_cause = "hashing_error"; | |
42 | int result; | |
43 | ||
44 | memset(entry->digest, 0, sizeof(entry->digest)); | |
45 | entry->template_name = IMA_TEMPLATE_NAME; | |
46 | entry->template_len = sizeof(entry->template); | |
47 | ||
48 | if (!violation) { | |
49 | result = ima_calc_template_hash(entry->template_len, | |
50 | &entry->template, | |
51 | entry->digest); | |
52 | if (result < 0) { | |
53 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, | |
54 | entry->template_name, op, | |
55 | audit_cause, result, 0); | |
56 | return result; | |
57 | } | |
58 | } | |
59 | result = ima_add_template_entry(entry, violation, op, inode); | |
60 | return result; | |
61 | } | |
62 | ||
63 | /* | |
64 | * ima_add_violation - add violation to measurement list. | |
65 | * | |
66 | * Violations are flagged in the measurement list with zero hash values. | |
67 | * By extending the PCR with 0xFF's instead of with zeroes, the PCR | |
68 | * value is invalidated. | |
69 | */ | |
70 | void ima_add_violation(struct inode *inode, const unsigned char *filename, | |
71 | const char *op, const char *cause) | |
72 | { | |
73 | struct ima_template_entry *entry; | |
74 | int violation = 1; | |
75 | int result; | |
76 | ||
77 | /* can overflow, only indicator */ | |
78 | atomic_long_inc(&ima_htable.violations); | |
79 | ||
80 | entry = kmalloc(sizeof(*entry), GFP_KERNEL); | |
81 | if (!entry) { | |
82 | result = -ENOMEM; | |
83 | goto err_out; | |
84 | } | |
85 | memset(&entry->template, 0, sizeof(entry->template)); | |
86 | strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX); | |
87 | result = ima_store_template(entry, violation, inode); | |
88 | if (result < 0) | |
89 | kfree(entry); | |
90 | err_out: | |
91 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, | |
92 | op, cause, result, 0); | |
93 | } | |
94 | ||
95 | /** | |
96 | * ima_must_measure - measure decision based on policy. | |
97 | * @inode: pointer to inode to measure | |
98 | * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE) | |
1e93d005 | 99 | * @function: calling function (FILE_CHECK, BPRM_CHECK, FILE_MMAP) |
3323eec9 MZ |
100 | * |
101 | * The policy is defined in terms of keypairs: | |
102 | * subj=, obj=, type=, func=, mask=, fsmagic= | |
103 | * subj,obj, and type: are LSM specific. | |
1e93d005 | 104 | * func: FILE_CHECK | BPRM_CHECK | FILE_MMAP |
3323eec9 MZ |
105 | * mask: contains the permission mask |
106 | * fsmagic: hex value | |
107 | * | |
108 | * Must be called with iint->mutex held. | |
109 | * | |
110 | * Return 0 to measure. Return 1 if already measured. | |
111 | * For matching a DONT_MEASURE policy, no policy, or other | |
112 | * error, return an error code. | |
113 | */ | |
114 | int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode, | |
115 | int mask, int function) | |
116 | { | |
117 | int must_measure; | |
118 | ||
119 | if (iint->flags & IMA_MEASURED) | |
120 | return 1; | |
121 | ||
122 | must_measure = ima_match_policy(inode, function, mask); | |
123 | return must_measure ? 0 : -EACCES; | |
124 | } | |
125 | ||
126 | /* | |
127 | * ima_collect_measurement - collect file measurement | |
128 | * | |
129 | * Calculate the file hash, if it doesn't already exist, | |
130 | * storing the measurement and i_version in the iint. | |
131 | * | |
132 | * Must be called with iint->mutex held. | |
133 | * | |
134 | * Return 0 on success, error code otherwise | |
135 | */ | |
136 | int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file) | |
137 | { | |
138 | int result = -EEXIST; | |
139 | ||
140 | if (!(iint->flags & IMA_MEASURED)) { | |
141 | u64 i_version = file->f_dentry->d_inode->i_version; | |
142 | ||
143 | memset(iint->digest, 0, IMA_DIGEST_SIZE); | |
144 | result = ima_calc_hash(file, iint->digest); | |
145 | if (!result) | |
146 | iint->version = i_version; | |
147 | } | |
148 | return result; | |
149 | } | |
150 | ||
151 | /* | |
152 | * ima_store_measurement - store file measurement | |
153 | * | |
154 | * Create an "ima" template and then store the template by calling | |
155 | * ima_store_template. | |
156 | * | |
157 | * We only get here if the inode has not already been measured, | |
158 | * but the measurement could already exist: | |
159 | * - multiple copies of the same file on either the same or | |
160 | * different filesystems. | |
161 | * - the inode was previously flushed as well as the iint info, | |
162 | * containing the hashing info. | |
163 | * | |
164 | * Must be called with iint->mutex held. | |
165 | */ | |
166 | void ima_store_measurement(struct ima_iint_cache *iint, struct file *file, | |
167 | const unsigned char *filename) | |
168 | { | |
169 | const char *op = "add_template_measure"; | |
170 | const char *audit_cause = "ENOMEM"; | |
171 | int result = -ENOMEM; | |
172 | struct inode *inode = file->f_dentry->d_inode; | |
173 | struct ima_template_entry *entry; | |
174 | int violation = 0; | |
175 | ||
176 | entry = kmalloc(sizeof(*entry), GFP_KERNEL); | |
177 | if (!entry) { | |
178 | integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, | |
179 | op, audit_cause, result, 0); | |
180 | return; | |
181 | } | |
182 | memset(&entry->template, 0, sizeof(entry->template)); | |
183 | memcpy(entry->template.digest, iint->digest, IMA_DIGEST_SIZE); | |
184 | strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX); | |
185 | ||
186 | result = ima_store_template(entry, violation, inode); | |
187 | if (!result) | |
188 | iint->flags |= IMA_MEASURED; | |
189 | else | |
190 | kfree(entry); | |
191 | } |