1 /*
2  * Copyright (C) 2013 Politecnico di Torino, Italy
3  *                    TORSEC group -- http://security.polito.it
4  *
5  * Author: Roberto Sassu <roberto.sassu@polito.it>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License as
9  * published by the Free Software Foundation, version 2 of the
10  * License.
11  *
12  * File: ima_template.c
13  *      Helpers to manage template descriptors.
14  */
15 #include <crypto/hash_info.h>
16 
17 #include "ima.h"
18 #include "ima_template_lib.h"
19 
20 static struct ima_template_desc defined_templates[] = {
21 	{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
22 	{.name = "ima-ng",.fmt = "d-ng|n-ng"},
23 	{.name = "ima-sig",.fmt = "d-ng|n-ng|sig"},
24 };
25 
26 static struct ima_template_field supported_fields[] = {
27 	{.field_id = "d",.field_init = ima_eventdigest_init,
28 	 .field_show = ima_show_template_digest},
29 	{.field_id = "n",.field_init = ima_eventname_init,
30 	 .field_show = ima_show_template_string},
31 	{.field_id = "d-ng",.field_init = ima_eventdigest_ng_init,
32 	 .field_show = ima_show_template_digest_ng},
33 	{.field_id = "n-ng",.field_init = ima_eventname_ng_init,
34 	 .field_show = ima_show_template_string},
35 	{.field_id = "sig",.field_init = ima_eventsig_init,
36 	 .field_show = ima_show_template_sig},
37 };
38 
39 static struct ima_template_desc *ima_template;
40 static struct ima_template_desc *lookup_template_desc(const char *name);
41 
42 static int __init ima_template_setup(char *str)
43 {
44 	struct ima_template_desc *template_desc;
45 	int template_len = strlen(str);
46 
47 	/*
48 	 * Verify that a template with the supplied name exists.
49 	 * If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
50 	 */
51 	template_desc = lookup_template_desc(str);
52 	if (!template_desc)
53 		return 1;
54 
55 	/*
56 	 * Verify whether the current hash algorithm is supported
57 	 * by the 'ima' template.
58 	 */
59 	if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 &&
60 	    ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) {
61 		pr_err("IMA: template does not support hash alg\n");
62 		return 1;
63 	}
64 
65 	ima_template = template_desc;
66 	return 1;
67 }
68 __setup("ima_template=", ima_template_setup);
69 
70 static struct ima_template_desc *lookup_template_desc(const char *name)
71 {
72 	int i;
73 
74 	for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
75 		if (strcmp(defined_templates[i].name, name) == 0)
76 			return defined_templates + i;
77 	}
78 
79 	return NULL;
80 }
81 
82 static struct ima_template_field *lookup_template_field(const char *field_id)
83 {
84 	int i;
85 
86 	for (i = 0; i < ARRAY_SIZE(supported_fields); i++)
87 		if (strncmp(supported_fields[i].field_id, field_id,
88 			    IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0)
89 			return &supported_fields[i];
90 	return NULL;
91 }
92 
93 static int template_fmt_size(const char *template_fmt)
94 {
95 	char c;
96 	int template_fmt_len = strlen(template_fmt);
97 	int i = 0, j = 0;
98 
99 	while (i < template_fmt_len) {
100 		c = template_fmt[i];
101 		if (c == '|')
102 			j++;
103 		i++;
104 	}
105 
106 	return j + 1;
107 }
108 
109 static int template_desc_init_fields(const char *template_fmt,
110 				     struct ima_template_field ***fields,
111 				     int *num_fields)
112 {
113 	char *c, *template_fmt_copy, *template_fmt_ptr;
114 	int template_num_fields = template_fmt_size(template_fmt);
115 	int i, result = 0;
116 
117 	if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX)
118 		return -EINVAL;
119 
120 	/* copying is needed as strsep() modifies the original buffer */
121 	template_fmt_copy = kstrdup(template_fmt, GFP_KERNEL);
122 	if (template_fmt_copy == NULL)
123 		return -ENOMEM;
124 
125 	*fields = kzalloc(template_num_fields * sizeof(*fields), GFP_KERNEL);
126 	if (*fields == NULL) {
127 		result = -ENOMEM;
128 		goto out;
129 	}
130 
131 	template_fmt_ptr = template_fmt_copy;
132 	for (i = 0; (c = strsep(&template_fmt_ptr, "|")) != NULL &&
133 	     i < template_num_fields; i++) {
134 		struct ima_template_field *f = lookup_template_field(c);
135 
136 		if (!f) {
137 			result = -ENOENT;
138 			goto out;
139 		}
140 		(*fields)[i] = f;
141 	}
142 	*num_fields = i;
143 out:
144 	if (result < 0) {
145 		kfree(*fields);
146 		*fields = NULL;
147 	}
148 	kfree(template_fmt_copy);
149 	return result;
150 }
151 
152 static int init_defined_templates(void)
153 {
154 	int i = 0;
155 	int result = 0;
156 
157 	/* Init defined templates. */
158 	for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
159 		struct ima_template_desc *template = &defined_templates[i];
160 
161 		result = template_desc_init_fields(template->fmt,
162 						   &(template->fields),
163 						   &(template->num_fields));
164 		if (result < 0)
165 			return result;
166 	}
167 	return result;
168 }
169 
170 struct ima_template_desc *ima_template_desc_current(void)
171 {
172 	if (!ima_template)
173 		ima_template =
174 		    lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE);
175 	return ima_template;
176 }
177 
178 int ima_init_template(void)
179 {
180 	int result;
181 
182 	result = init_defined_templates();
183 	if (result < 0)
184 		return result;
185 
186 	return 0;
187 }
188