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