security/integrity/ima/ima_template_lib.c

   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_EVENT_NAME,
  31         DATA_FMT_STRING,
  32         DATA_FMT_HEX
  33 };
  34
  35 static int ima_write_template_field_data(const void *data, const u32 datalen,
  36                                          enum data_formats datafmt,
  37                                          struct ima_field_data *field_data)
  38 {
  39         u8 *buf, *buf_ptr;
  40         u32 buflen;
  41
  42         switch (datafmt) {
  43         case DATA_FMT_EVENT_NAME:
  44                 buflen = IMA_EVENT_NAME_LEN_MAX + 1;
  45                 break;
  46         case DATA_FMT_STRING:
  47                 buflen = datalen + 1;
  48                 break;
  49         default:
  50                 buflen = datalen;
  51         }
  52
  53         buf = kzalloc(buflen, GFP_KERNEL);
  54         if (!buf)
  55                 return -ENOMEM;
  56
  57         memcpy(buf, data, datalen);
  58
  59         /*
  60          * Replace all space characters with underscore for event names and
  61          * strings. This avoid that, during the parsing of a measurements list,
  62          * filenames with spaces or that end with the suffix ' (deleted)' are
  63          * split into multiple template fields (the space is the delimitator
  64          * character for measurements lists in ASCII format).
  65          */
  66         if (datafmt == DATA_FMT_EVENT_NAME || datafmt == DATA_FMT_STRING) {
  67                 for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
  68                         if (*buf_ptr == ' ')
  69                                 *buf_ptr = '_';
  70         }
  71
  72         field_data->data = buf;
  73         field_data->len = buflen;
  74         return 0;
  75 }
  76
  77 static void ima_show_template_data_ascii(struct seq_file *m,
  78                                          enum ima_show_type show,
  79                                          enum data_formats datafmt,
  80                                          struct ima_field_data *field_data)
  81 {
  82         u8 *buf_ptr = field_data->data, buflen = field_data->len;
  83
  84         switch (datafmt) {
  85         case DATA_FMT_DIGEST_WITH_ALGO:
  86                 buf_ptr = strnchr(field_data->data, buflen, ':');
  87                 if (buf_ptr != field_data->data)
  88                         seq_printf(m, "%s", field_data->data);
  89
  90                 /* skip ':' and '\0' */
  91                 buf_ptr += 2;
  92                 buflen -= buf_ptr - field_data->data;
  93         case DATA_FMT_DIGEST:
  94         case DATA_FMT_HEX:
  95                 if (!buflen)
  96                         break;
  97                 ima_print_digest(m, buf_ptr, buflen);
  98                 break;
  99         case DATA_FMT_STRING:
 100                 seq_printf(m, "%s", buf_ptr);
 101                 break;
 102         default:
 103                 break;
 104         }
 105 }
 106
 107 static void ima_show_template_data_binary(struct seq_file *m,
 108                                           enum ima_show_type show,
 109                                           enum data_formats datafmt,
 110                                           struct ima_field_data *field_data)
 111 {
 112         if (show != IMA_SHOW_BINARY_NO_FIELD_LEN)
 113                 ima_putc(m, &field_data->len, sizeof(u32));
 114
 115         if (!field_data->len)
 116                 return;
 117
 118         ima_putc(m, field_data->data, field_data->len);
 119 }
 120
 121 static void ima_show_template_field_data(struct seq_file *m,
 122                                          enum ima_show_type show,
 123                                          enum data_formats datafmt,
 124                                          struct ima_field_data *field_data)
 125 {
 126         switch (show) {
 127         case IMA_SHOW_ASCII:
 128                 ima_show_template_data_ascii(m, show, datafmt, field_data);
 129                 break;
 130         case IMA_SHOW_BINARY:
 131         case IMA_SHOW_BINARY_NO_FIELD_LEN:
 132                 ima_show_template_data_binary(m, show, datafmt, field_data);
 133                 break;
 134         default:
 135                 break;
 136         }
 137 }
 138
 139 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
 140                               struct ima_field_data *field_data)
 141 {
 142         ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
 143 }
 144
 145 void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
 146                                  struct ima_field_data *field_data)
 147 {
 148         ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
 149                                      field_data);
 150 }
 151
 152 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
 153                               struct ima_field_data *field_data)
 154 {
 155         ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
 156 }
 157
 158 void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
 159                            struct ima_field_data *field_data)
 160 {
 161         ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
 162 }
 163
 164 static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
 165                                        struct ima_field_data *field_data)
 166 {
 167         /*
 168          * digest formats:
 169          *  - DATA_FMT_DIGEST: digest
 170          *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
 171          *    where <hash algo> is provided if the hash algoritm is not
 172          *    SHA1 or MD5
 173          */
 174         u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
 175         enum data_formats fmt = DATA_FMT_DIGEST;
 176         u32 offset = 0;
 177
 178         if (hash_algo < HASH_ALGO__LAST) {
 179                 fmt = DATA_FMT_DIGEST_WITH_ALGO;
 180                 offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
 181                                    hash_algo_name[hash_algo]);
 182                 buffer[offset] = ':';
 183                 offset += 2;
 184         }
 185
 186         if (digest)
 187                 memcpy(buffer + offset, digest, digestsize);
 188         else
 189                 /*
 190                  * If digest is NULL, the event being recorded is a violation.
 191                  * Make room for the digest by increasing the offset of
 192                  * IMA_DIGEST_SIZE.
 193                  */
 194                 offset += IMA_DIGEST_SIZE;
 195
 196         return ima_write_template_field_data(buffer, offset + digestsize,
 197                                              fmt, field_data);
 198 }
 199
 200 /*
 201  * This function writes the digest of an event (with size limit).
 202  */
 203 int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
 204                          const unsigned char *filename,
 205                          struct evm_ima_xattr_data *xattr_value, int xattr_len,
 206                          struct ima_field_data *field_data)
 207 {
 208         struct {
 209                 struct ima_digest_data hdr;
 210                 char digest[IMA_MAX_DIGEST_SIZE];
 211         } hash;
 212         u8 *cur_digest = NULL;
 213         u32 cur_digestsize = 0;
 214         struct inode *inode;
 215         int result;
 216
 217         memset(&hash, 0, sizeof(hash));
 218
 219         if (!iint)              /* recording a violation. */
 220                 goto out;
 221
 222         if (ima_template_hash_algo_allowed(iint->ima_hash->algo)) {
 223                 cur_digest = iint->ima_hash->digest;
 224                 cur_digestsize = iint->ima_hash->length;
 225                 goto out;
 226         }
 227
 228         if (!file)              /* missing info to re-calculate the digest */
 229                 return -EINVAL;
 230
 231         inode = file_inode(file);
 232         hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
 233             ima_hash_algo : HASH_ALGO_SHA1;
 234         result = ima_calc_file_hash(file, &hash.hdr);
 235         if (result) {
 236                 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
 237                                     filename, "collect_data",
 238                                     "failed", result, 0);
 239                 return result;
 240         }
 241         cur_digest = hash.hdr.digest;
 242         cur_digestsize = hash.hdr.length;
 243 out:
 244         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 245                                            HASH_ALGO__LAST, field_data);
 246 }
 247
 248 /*
 249  * This function writes the digest of an event (without size limit).
 250  */
 251 int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
 252                             struct file *file, const unsigned char *filename,
 253                             struct evm_ima_xattr_data *xattr_value,
 254                             int xattr_len, struct ima_field_data *field_data)
 255 {
 256         u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
 257         u32 cur_digestsize = 0;
 258
 259         /* If iint is NULL, we are recording a violation. */
 260         if (!iint)
 261                 goto out;
 262
 263         cur_digest = iint->ima_hash->digest;
 264         cur_digestsize = iint->ima_hash->length;
 265
 266         hash_algo = iint->ima_hash->algo;
 267 out:
 268         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 269                                            hash_algo, field_data);
 270 }
 271
 272 static int ima_eventname_init_common(struct integrity_iint_cache *iint,
 273                                      struct file *file,
 274                                      const unsigned char *filename,
 275                                      struct ima_field_data *field_data,
 276                                      bool size_limit)
 277 {
 278         const char *cur_filename = NULL;
 279         u32 cur_filename_len = 0;
 280         enum data_formats fmt = size_limit ?
 281             DATA_FMT_EVENT_NAME : DATA_FMT_STRING;
 282
 283         BUG_ON(filename == NULL && file == NULL);
 284
 285         if (filename) {
 286                 cur_filename = filename;
 287                 cur_filename_len = strlen(filename);
 288
 289                 if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
 290                         goto out;
 291         }
 292
 293         if (file) {
 294                 cur_filename = file->f_dentry->d_name.name;
 295                 cur_filename_len = strlen(cur_filename);
 296         } else
 297                 /*
 298                  * Truncate filename if the latter is too long and
 299                  * the file descriptor is not available.
 300                  */
 301                 cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
 302 out:
 303         return ima_write_template_field_data(cur_filename, cur_filename_len,
 304                                              fmt, field_data);
 305 }
 306
 307 /*
 308  * This function writes the name of an event (with size limit).
 309  */
 310 int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
 311                        const unsigned char *filename,
 312                        struct evm_ima_xattr_data *xattr_value, int xattr_len,
 313                        struct ima_field_data *field_data)
 314 {
 315         return ima_eventname_init_common(iint, file, filename,
 316                                          field_data, true);
 317 }
 318
 319 /*
 320  * This function writes the name of an event (without size limit).
 321  */
 322 int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file,
 323                           const unsigned char *filename,
 324                           struct evm_ima_xattr_data *xattr_value, int xattr_len,
 325                           struct ima_field_data *field_data)
 326 {
 327         return ima_eventname_init_common(iint, file, filename,
 328                                          field_data, false);
 329 }
 330
 331 /*
 332  *  ima_eventsig_init - include the file signature as part of the template data
 333  */
 334 int ima_eventsig_init(struct integrity_iint_cache *iint, struct file *file,
 335                       const unsigned char *filename,
 336                       struct evm_ima_xattr_data *xattr_value, int xattr_len,
 337                       struct ima_field_data *field_data)
 338 {
 339         enum data_formats fmt = DATA_FMT_HEX;
 340         int rc = 0;
 341
 342         if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
 343                 goto out;
 344
 345         rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
 346                                            field_data);
 347 out:
 348         return rc;
 349 }