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 16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 17 18 #include <crypto/hash_info.h> 19 20 #include "ima.h" 21 #include "ima_template_lib.h" 22 23 static struct ima_template_desc defined_templates[] = { 24 {.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT}, 25 {.name = "ima-ng", .fmt = "d-ng|n-ng"}, 26 {.name = "ima-sig", .fmt = "d-ng|n-ng|sig"}, 27 {.name = "", .fmt = ""}, /* placeholder for a custom format */ 28 }; 29 30 static struct ima_template_field supported_fields[] = { 31 {.field_id = "d", .field_init = ima_eventdigest_init, 32 .field_show = ima_show_template_digest}, 33 {.field_id = "n", .field_init = ima_eventname_init, 34 .field_show = ima_show_template_string}, 35 {.field_id = "d-ng", .field_init = ima_eventdigest_ng_init, 36 .field_show = ima_show_template_digest_ng}, 37 {.field_id = "n-ng", .field_init = ima_eventname_ng_init, 38 .field_show = ima_show_template_string}, 39 {.field_id = "sig", .field_init = ima_eventsig_init, 40 .field_show = ima_show_template_sig}, 41 }; 42 43 static struct ima_template_desc *ima_template; 44 static struct ima_template_desc *lookup_template_desc(const char *name); 45 static int template_desc_init_fields(const char *template_fmt, 46 struct ima_template_field ***fields, 47 int *num_fields); 48 49 static int __init ima_template_setup(char *str) 50 { 51 struct ima_template_desc *template_desc; 52 int template_len = strlen(str); 53 54 if (ima_template) 55 return 1; 56 57 /* 58 * Verify that a template with the supplied name exists. 59 * If not, use CONFIG_IMA_DEFAULT_TEMPLATE. 60 */ 61 template_desc = lookup_template_desc(str); 62 if (!template_desc) { 63 pr_err("template %s not found, using %s\n", 64 str, CONFIG_IMA_DEFAULT_TEMPLATE); 65 return 1; 66 } 67 68 /* 69 * Verify whether the current hash algorithm is supported 70 * by the 'ima' template. 71 */ 72 if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 && 73 ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) { 74 pr_err("template does not support hash alg\n"); 75 return 1; 76 } 77 78 ima_template = template_desc; 79 return 1; 80 } 81 __setup("ima_template=", ima_template_setup); 82 83 static int __init ima_template_fmt_setup(char *str) 84 { 85 int num_templates = ARRAY_SIZE(defined_templates); 86 87 if (ima_template) 88 return 1; 89 90 if (template_desc_init_fields(str, NULL, NULL) < 0) { 91 pr_err("format string '%s' not valid, using template %s\n", 92 str, CONFIG_IMA_DEFAULT_TEMPLATE); 93 return 1; 94 } 95 96 defined_templates[num_templates - 1].fmt = str; 97 ima_template = defined_templates + num_templates - 1; 98 return 1; 99 } 100 __setup("ima_template_fmt=", ima_template_fmt_setup); 101 102 static struct ima_template_desc *lookup_template_desc(const char *name) 103 { 104 int i; 105 106 for (i = 0; i < ARRAY_SIZE(defined_templates); i++) { 107 if (strcmp(defined_templates[i].name, name) == 0) 108 return defined_templates + i; 109 } 110 111 return NULL; 112 } 113 114 static struct ima_template_field *lookup_template_field(const char *field_id) 115 { 116 int i; 117 118 for (i = 0; i < ARRAY_SIZE(supported_fields); i++) 119 if (strncmp(supported_fields[i].field_id, field_id, 120 IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0) 121 return &supported_fields[i]; 122 return NULL; 123 } 124 125 static int template_fmt_size(const char *template_fmt) 126 { 127 char c; 128 int template_fmt_len = strlen(template_fmt); 129 int i = 0, j = 0; 130 131 while (i < template_fmt_len) { 132 c = template_fmt[i]; 133 if (c == '|') 134 j++; 135 i++; 136 } 137 138 return j + 1; 139 } 140 141 static int template_desc_init_fields(const char *template_fmt, 142 struct ima_template_field ***fields, 143 int *num_fields) 144 { 145 const char *template_fmt_ptr; 146 struct ima_template_field *found_fields[IMA_TEMPLATE_NUM_FIELDS_MAX]; 147 int template_num_fields = template_fmt_size(template_fmt); 148 int i, len; 149 150 if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) { 151 pr_err("format string '%s' contains too many fields\n", 152 template_fmt); 153 return -EINVAL; 154 } 155 156 for (i = 0, template_fmt_ptr = template_fmt; i < template_num_fields; 157 i++, template_fmt_ptr += len + 1) { 158 char tmp_field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN + 1]; 159 160 len = strchrnul(template_fmt_ptr, '|') - template_fmt_ptr; 161 if (len == 0 || len > IMA_TEMPLATE_FIELD_ID_MAX_LEN) { 162 pr_err("Invalid field with length %d\n", len); 163 return -EINVAL; 164 } 165 166 memcpy(tmp_field_id, template_fmt_ptr, len); 167 tmp_field_id[len] = '\0'; 168 found_fields[i] = lookup_template_field(tmp_field_id); 169 if (!found_fields[i]) { 170 pr_err("field '%s' not found\n", tmp_field_id); 171 return -ENOENT; 172 } 173 } 174 175 if (fields && num_fields) { 176 *fields = kmalloc_array(i, sizeof(*fields), GFP_KERNEL); 177 if (*fields == NULL) 178 return -ENOMEM; 179 180 memcpy(*fields, found_fields, i * sizeof(*fields)); 181 *num_fields = i; 182 } 183 184 return 0; 185 } 186 187 struct ima_template_desc *ima_template_desc_current(void) 188 { 189 if (!ima_template) 190 ima_template = 191 lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE); 192 return ima_template; 193 } 194 195 int __init ima_init_template(void) 196 { 197 struct ima_template_desc *template = ima_template_desc_current(); 198 int result; 199 200 result = template_desc_init_fields(template->fmt, 201 &(template->fields), 202 &(template->num_fields)); 203 if (result < 0) 204 pr_err("template %s init failed, result: %d\n", 205 (strlen(template->name) ? 206 template->name : template->fmt), result); 207 208 return result; 209 } 210