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_lib.c 13 * Library of supported template fields. 14 */ 15 #include <crypto/hash_info.h> 16 17 #include "ima_template_lib.h" 18 19 static bool ima_template_hash_algo_allowed(u8 algo) 20 { 21 if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5) 22 return true; 23 24 return false; 25 } 26 27 enum data_formats { 28 DATA_FMT_DIGEST = 0, 29 DATA_FMT_DIGEST_WITH_ALGO, 30 DATA_FMT_STRING, 31 DATA_FMT_HEX 32 }; 33 34 static int ima_write_template_field_data(const void *data, const u32 datalen, 35 enum data_formats datafmt, 36 struct ima_field_data *field_data) 37 { 38 u8 *buf, *buf_ptr; 39 u32 buflen = datalen; 40 41 if (datafmt == DATA_FMT_STRING) 42 buflen = datalen + 1; 43 44 buf = kzalloc(buflen, GFP_KERNEL); 45 if (!buf) 46 return -ENOMEM; 47 48 memcpy(buf, data, datalen); 49 50 /* 51 * Replace all space characters with underscore for event names and 52 * strings. This avoid that, during the parsing of a measurements list, 53 * filenames with spaces or that end with the suffix ' (deleted)' are 54 * split into multiple template fields (the space is the delimitator 55 * character for measurements lists in ASCII format). 56 */ 57 if (datafmt == DATA_FMT_STRING) { 58 for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++) 59 if (*buf_ptr == ' ') 60 *buf_ptr = '_'; 61 } 62 63 field_data->data = buf; 64 field_data->len = buflen; 65 return 0; 66 } 67 68 static void ima_show_template_data_ascii(struct seq_file *m, 69 enum ima_show_type show, 70 enum data_formats datafmt, 71 struct ima_field_data *field_data) 72 { 73 u8 *buf_ptr = field_data->data, buflen = field_data->len; 74 75 switch (datafmt) { 76 case DATA_FMT_DIGEST_WITH_ALGO: 77 buf_ptr = strnchr(field_data->data, buflen, ':'); 78 if (buf_ptr != field_data->data) 79 seq_printf(m, "%s", field_data->data); 80 81 /* skip ':' and '\0' */ 82 buf_ptr += 2; 83 buflen -= buf_ptr - field_data->data; 84 case DATA_FMT_DIGEST: 85 case DATA_FMT_HEX: 86 if (!buflen) 87 break; 88 ima_print_digest(m, buf_ptr, buflen); 89 break; 90 case DATA_FMT_STRING: 91 seq_printf(m, "%s", buf_ptr); 92 break; 93 default: 94 break; 95 } 96 } 97 98 static void ima_show_template_data_binary(struct seq_file *m, 99 enum ima_show_type show, 100 enum data_formats datafmt, 101 struct ima_field_data *field_data) 102 { 103 u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ? 104 strlen(field_data->data) : field_data->len; 105 106 if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) 107 ima_putc(m, &len, sizeof(len)); 108 109 if (!len) 110 return; 111 112 ima_putc(m, field_data->data, len); 113 } 114 115 static void ima_show_template_field_data(struct seq_file *m, 116 enum ima_show_type show, 117 enum data_formats datafmt, 118 struct ima_field_data *field_data) 119 { 120 switch (show) { 121 case IMA_SHOW_ASCII: 122 ima_show_template_data_ascii(m, show, datafmt, field_data); 123 break; 124 case IMA_SHOW_BINARY: 125 case IMA_SHOW_BINARY_NO_FIELD_LEN: 126 case IMA_SHOW_BINARY_OLD_STRING_FMT: 127 ima_show_template_data_binary(m, show, datafmt, field_data); 128 break; 129 default: 130 break; 131 } 132 } 133 134 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show, 135 struct ima_field_data *field_data) 136 { 137 ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data); 138 } 139 140 void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show, 141 struct ima_field_data *field_data) 142 { 143 ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO, 144 field_data); 145 } 146 147 void ima_show_template_string(struct seq_file *m, enum ima_show_type show, 148 struct ima_field_data *field_data) 149 { 150 ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data); 151 } 152 153 void ima_show_template_sig(struct seq_file *m, enum ima_show_type show, 154 struct ima_field_data *field_data) 155 { 156 ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data); 157 } 158 159 static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo, 160 struct ima_field_data *field_data) 161 { 162 /* 163 * digest formats: 164 * - DATA_FMT_DIGEST: digest 165 * - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest, 166 * where <hash algo> is provided if the hash algoritm is not 167 * SHA1 or MD5 168 */ 169 u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 }; 170 enum data_formats fmt = DATA_FMT_DIGEST; 171 u32 offset = 0; 172 173 if (hash_algo < HASH_ALGO__LAST) { 174 fmt = DATA_FMT_DIGEST_WITH_ALGO; 175 offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s", 176 hash_algo_name[hash_algo]); 177 buffer[offset] = ':'; 178 offset += 2; 179 } 180 181 if (digest) 182 memcpy(buffer + offset, digest, digestsize); 183 else 184 /* 185 * If digest is NULL, the event being recorded is a violation. 186 * Make room for the digest by increasing the offset of 187 * IMA_DIGEST_SIZE. 188 */ 189 offset += IMA_DIGEST_SIZE; 190 191 return ima_write_template_field_data(buffer, offset + digestsize, 192 fmt, field_data); 193 } 194 195 /* 196 * This function writes the digest of an event (with size limit). 197 */ 198 int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file, 199 const unsigned char *filename, 200 struct evm_ima_xattr_data *xattr_value, int xattr_len, 201 struct ima_field_data *field_data) 202 { 203 struct { 204 struct ima_digest_data hdr; 205 char digest[IMA_MAX_DIGEST_SIZE]; 206 } hash; 207 u8 *cur_digest = NULL; 208 u32 cur_digestsize = 0; 209 struct inode *inode; 210 int result; 211 212 memset(&hash, 0, sizeof(hash)); 213 214 if (!iint) /* recording a violation. */ 215 goto out; 216 217 if (ima_template_hash_algo_allowed(iint->ima_hash->algo)) { 218 cur_digest = iint->ima_hash->digest; 219 cur_digestsize = iint->ima_hash->length; 220 goto out; 221 } 222 223 if (!file) /* missing info to re-calculate the digest */ 224 return -EINVAL; 225 226 inode = file_inode(file); 227 hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ? 228 ima_hash_algo : HASH_ALGO_SHA1; 229 result = ima_calc_file_hash(file, &hash.hdr); 230 if (result) { 231 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, 232 filename, "collect_data", 233 "failed", result, 0); 234 return result; 235 } 236 cur_digest = hash.hdr.digest; 237 cur_digestsize = hash.hdr.length; 238 out: 239 return ima_eventdigest_init_common(cur_digest, cur_digestsize, 240 HASH_ALGO__LAST, field_data); 241 } 242 243 /* 244 * This function writes the digest of an event (without size limit). 245 */ 246 int ima_eventdigest_ng_init(struct integrity_iint_cache *iint, 247 struct file *file, const unsigned char *filename, 248 struct evm_ima_xattr_data *xattr_value, 249 int xattr_len, struct ima_field_data *field_data) 250 { 251 u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1; 252 u32 cur_digestsize = 0; 253 254 /* If iint is NULL, we are recording a violation. */ 255 if (!iint) 256 goto out; 257 258 cur_digest = iint->ima_hash->digest; 259 cur_digestsize = iint->ima_hash->length; 260 261 hash_algo = iint->ima_hash->algo; 262 out: 263 return ima_eventdigest_init_common(cur_digest, cur_digestsize, 264 hash_algo, field_data); 265 } 266 267 static int ima_eventname_init_common(struct integrity_iint_cache *iint, 268 struct file *file, 269 const unsigned char *filename, 270 struct ima_field_data *field_data, 271 bool size_limit) 272 { 273 const char *cur_filename = NULL; 274 u32 cur_filename_len = 0; 275 276 BUG_ON(filename == NULL && file == NULL); 277 278 if (filename) { 279 cur_filename = filename; 280 cur_filename_len = strlen(filename); 281 282 if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX) 283 goto out; 284 } 285 286 if (file) { 287 cur_filename = file->f_dentry->d_name.name; 288 cur_filename_len = strlen(cur_filename); 289 } else 290 /* 291 * Truncate filename if the latter is too long and 292 * the file descriptor is not available. 293 */ 294 cur_filename_len = IMA_EVENT_NAME_LEN_MAX; 295 out: 296 return ima_write_template_field_data(cur_filename, cur_filename_len, 297 DATA_FMT_STRING, field_data); 298 } 299 300 /* 301 * This function writes the name of an event (with size limit). 302 */ 303 int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file, 304 const unsigned char *filename, 305 struct evm_ima_xattr_data *xattr_value, int xattr_len, 306 struct ima_field_data *field_data) 307 { 308 return ima_eventname_init_common(iint, file, filename, 309 field_data, true); 310 } 311 312 /* 313 * This function writes the name of an event (without size limit). 314 */ 315 int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file, 316 const unsigned char *filename, 317 struct evm_ima_xattr_data *xattr_value, int xattr_len, 318 struct ima_field_data *field_data) 319 { 320 return ima_eventname_init_common(iint, file, filename, 321 field_data, false); 322 } 323 324 /* 325 * ima_eventsig_init - include the file signature as part of the template data 326 */ 327 int ima_eventsig_init(struct integrity_iint_cache *iint, struct file *file, 328 const unsigned char *filename, 329 struct evm_ima_xattr_data *xattr_value, int xattr_len, 330 struct ima_field_data *field_data) 331 { 332 enum data_formats fmt = DATA_FMT_HEX; 333 int rc = 0; 334 335 if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG)) 336 goto out; 337 338 rc = ima_write_template_field_data(xattr_value, xattr_len, fmt, 339 field_data); 340 out: 341 return rc; 342 } 343