root/security/integrity/ima/ima_template_lib.c

DEFINITIONS

1. ima_template_hash_algo_allowed
2. ima_write_template_field_data
3. ima_show_template_data_ascii
4. ima_show_template_data_binary
5. ima_show_template_field_data
6. ima_show_template_digest
7. ima_show_template_digest_ng
8. ima_show_template_string
9. ima_show_template_sig
10. ima_show_template_buf
11. ima_parse_buf
12. ima_eventdigest_init_common
13. ima_eventdigest_init
14. ima_eventdigest_ng_init
15. ima_eventdigest_modsig_init
16. ima_eventname_init_common
17. ima_eventname_init
18. ima_eventname_ng_init
19. ima_eventsig_init
20. ima_eventbuf_init
21. ima_eventmodsig_init

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2013 Politecnico di Torino, Italy
   4  *                    TORSEC group -- http://security.polito.it
   5  *
   6  * Author: Roberto Sassu <roberto.sassu@polito.it>
   7  *
   8  * File: ima_template_lib.c
   9  *      Library of supported template fields.
  10  */
  11 
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13 
  14 #include "ima_template_lib.h"
  15 
  16 static bool ima_template_hash_algo_allowed(u8 algo)
  17 {
  18         if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
  19                 return true;
  20 
  21         return false;
  22 }
  23 
  24 enum data_formats {
  25         DATA_FMT_DIGEST = 0,
  26         DATA_FMT_DIGEST_WITH_ALGO,
  27         DATA_FMT_STRING,
  28         DATA_FMT_HEX
  29 };
  30 
  31 static int ima_write_template_field_data(const void *data, const u32 datalen,
  32                                          enum data_formats datafmt,
  33                                          struct ima_field_data *field_data)
  34 {
  35         u8 *buf, *buf_ptr;
  36         u32 buflen = datalen;
  37 
  38         if (datafmt == DATA_FMT_STRING)
  39                 buflen = datalen + 1;
  40 
  41         buf = kzalloc(buflen, GFP_KERNEL);
  42         if (!buf)
  43                 return -ENOMEM;
  44 
  45         memcpy(buf, data, datalen);
  46 
  47         /*
  48          * Replace all space characters with underscore for event names and
  49          * strings. This avoid that, during the parsing of a measurements list,
  50          * filenames with spaces or that end with the suffix ' (deleted)' are
  51          * split into multiple template fields (the space is the delimitator
  52          * character for measurements lists in ASCII format).
  53          */
  54         if (datafmt == DATA_FMT_STRING) {
  55                 for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
  56                         if (*buf_ptr == ' ')
  57                                 *buf_ptr = '_';
  58         }
  59 
  60         field_data->data = buf;
  61         field_data->len = buflen;
  62         return 0;
  63 }
  64 
  65 static void ima_show_template_data_ascii(struct seq_file *m,
  66                                          enum ima_show_type show,
  67                                          enum data_formats datafmt,
  68                                          struct ima_field_data *field_data)
  69 {
  70         u8 *buf_ptr = field_data->data;
  71         u32 buflen = field_data->len;
  72 
  73         switch (datafmt) {
  74         case DATA_FMT_DIGEST_WITH_ALGO:
  75                 buf_ptr = strnchr(field_data->data, buflen, ':');
  76                 if (buf_ptr != field_data->data)
  77                         seq_printf(m, "%s", field_data->data);
  78 
  79                 /* skip ':' and '\0' */
  80                 buf_ptr += 2;
  81                 buflen -= buf_ptr - field_data->data;
  82                 /* fall through */
  83         case DATA_FMT_DIGEST:
  84         case DATA_FMT_HEX:
  85                 if (!buflen)
  86                         break;
  87                 ima_print_digest(m, buf_ptr, buflen);
  88                 break;
  89         case DATA_FMT_STRING:
  90                 seq_printf(m, "%s", buf_ptr);
  91                 break;
  92         default:
  93                 break;
  94         }
  95 }
  96 
  97 static void ima_show_template_data_binary(struct seq_file *m,
  98                                           enum ima_show_type show,
  99                                           enum data_formats datafmt,
 100                                           struct ima_field_data *field_data)
 101 {
 102         u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
 103             strlen(field_data->data) : field_data->len;
 104 
 105         if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
 106                 u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
 107 
 108                 ima_putc(m, &field_len, sizeof(field_len));
 109         }
 110 
 111         if (!len)
 112                 return;
 113 
 114         ima_putc(m, field_data->data, len);
 115 }
 116 
 117 static void ima_show_template_field_data(struct seq_file *m,
 118                                          enum ima_show_type show,
 119                                          enum data_formats datafmt,
 120                                          struct ima_field_data *field_data)
 121 {
 122         switch (show) {
 123         case IMA_SHOW_ASCII:
 124                 ima_show_template_data_ascii(m, show, datafmt, field_data);
 125                 break;
 126         case IMA_SHOW_BINARY:
 127         case IMA_SHOW_BINARY_NO_FIELD_LEN:
 128         case IMA_SHOW_BINARY_OLD_STRING_FMT:
 129                 ima_show_template_data_binary(m, show, datafmt, field_data);
 130                 break;
 131         default:
 132                 break;
 133         }
 134 }
 135 
 136 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
 137                               struct ima_field_data *field_data)
 138 {
 139         ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
 140 }
 141 
 142 void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
 143                                  struct ima_field_data *field_data)
 144 {
 145         ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
 146                                      field_data);
 147 }
 148 
 149 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
 150                               struct ima_field_data *field_data)
 151 {
 152         ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
 153 }
 154 
 155 void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
 156                            struct ima_field_data *field_data)
 157 {
 158         ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
 159 }
 160 
 161 void ima_show_template_buf(struct seq_file *m, enum ima_show_type show,
 162                            struct ima_field_data *field_data)
 163 {
 164         ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
 165 }
 166 
 167 /**
 168  * ima_parse_buf() - Parses lengths and data from an input buffer
 169  * @bufstartp:       Buffer start address.
 170  * @bufendp:         Buffer end address.
 171  * @bufcurp:         Pointer to remaining (non-parsed) data.
 172  * @maxfields:       Length of fields array.
 173  * @fields:          Array containing lengths and pointers of parsed data.
 174  * @curfields:       Number of array items containing parsed data.
 175  * @len_mask:        Bitmap (if bit is set, data length should not be parsed).
 176  * @enforce_mask:    Check if curfields == maxfields and/or bufcurp == bufendp.
 177  * @bufname:         String identifier of the input buffer.
 178  *
 179  * Return: 0 on success, -EINVAL on error.
 180  */
 181 int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
 182                   int maxfields, struct ima_field_data *fields, int *curfields,
 183                   unsigned long *len_mask, int enforce_mask, char *bufname)
 184 {
 185         void *bufp = bufstartp;
 186         int i;
 187 
 188         for (i = 0; i < maxfields; i++) {
 189                 if (len_mask == NULL || !test_bit(i, len_mask)) {
 190                         if (bufp > (bufendp - sizeof(u32)))
 191                                 break;
 192 
 193                         fields[i].len = *(u32 *)bufp;
 194                         if (ima_canonical_fmt)
 195                                 fields[i].len = le32_to_cpu(fields[i].len);
 196 
 197                         bufp += sizeof(u32);
 198                 }
 199 
 200                 if (bufp > (bufendp - fields[i].len))
 201                         break;
 202 
 203                 fields[i].data = bufp;
 204                 bufp += fields[i].len;
 205         }
 206 
 207         if ((enforce_mask & ENFORCE_FIELDS) && i != maxfields) {
 208                 pr_err("%s: nr of fields mismatch: expected: %d, current: %d\n",
 209                        bufname, maxfields, i);
 210                 return -EINVAL;
 211         }
 212 
 213         if ((enforce_mask & ENFORCE_BUFEND) && bufp != bufendp) {
 214                 pr_err("%s: buf end mismatch: expected: %p, current: %p\n",
 215                        bufname, bufendp, bufp);
 216                 return -EINVAL;
 217         }
 218 
 219         if (curfields)
 220                 *curfields = i;
 221 
 222         if (bufcurp)
 223                 *bufcurp = bufp;
 224 
 225         return 0;
 226 }
 227 
 228 static int ima_eventdigest_init_common(const u8 *digest, u32 digestsize,
 229                                        u8 hash_algo,
 230                                        struct ima_field_data *field_data)
 231 {
 232         /*
 233          * digest formats:
 234          *  - DATA_FMT_DIGEST: digest
 235          *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
 236          *    where <hash algo> is provided if the hash algoritm is not
 237          *    SHA1 or MD5
 238          */
 239         u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
 240         enum data_formats fmt = DATA_FMT_DIGEST;
 241         u32 offset = 0;
 242 
 243         if (hash_algo < HASH_ALGO__LAST) {
 244                 fmt = DATA_FMT_DIGEST_WITH_ALGO;
 245                 offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
 246                                    hash_algo_name[hash_algo]);
 247                 buffer[offset] = ':';
 248                 offset += 2;
 249         }
 250 
 251         if (digest)
 252                 memcpy(buffer + offset, digest, digestsize);
 253         else
 254                 /*
 255                  * If digest is NULL, the event being recorded is a violation.
 256                  * Make room for the digest by increasing the offset of
 257                  * IMA_DIGEST_SIZE.
 258                  */
 259                 offset += IMA_DIGEST_SIZE;
 260 
 261         return ima_write_template_field_data(buffer, offset + digestsize,
 262                                              fmt, field_data);
 263 }
 264 
 265 /*
 266  * This function writes the digest of an event (with size limit).
 267  */
 268 int ima_eventdigest_init(struct ima_event_data *event_data,
 269                          struct ima_field_data *field_data)
 270 {
 271         struct {
 272                 struct ima_digest_data hdr;
 273                 char digest[IMA_MAX_DIGEST_SIZE];
 274         } hash;
 275         u8 *cur_digest = NULL;
 276         u32 cur_digestsize = 0;
 277         struct inode *inode;
 278         int result;
 279 
 280         memset(&hash, 0, sizeof(hash));
 281 
 282         if (event_data->violation)      /* recording a violation. */
 283                 goto out;
 284 
 285         if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
 286                 cur_digest = event_data->iint->ima_hash->digest;
 287                 cur_digestsize = event_data->iint->ima_hash->length;
 288                 goto out;
 289         }
 290 
 291         if (!event_data->file)  /* missing info to re-calculate the digest */
 292                 return -EINVAL;
 293 
 294         inode = file_inode(event_data->file);
 295         hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
 296             ima_hash_algo : HASH_ALGO_SHA1;
 297         result = ima_calc_file_hash(event_data->file, &hash.hdr);
 298         if (result) {
 299                 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
 300                                     event_data->filename, "collect_data",
 301                                     "failed", result, 0);
 302                 return result;
 303         }
 304         cur_digest = hash.hdr.digest;
 305         cur_digestsize = hash.hdr.length;
 306 out:
 307         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 308                                            HASH_ALGO__LAST, field_data);
 309 }
 310 
 311 /*
 312  * This function writes the digest of an event (without size limit).
 313  */
 314 int ima_eventdigest_ng_init(struct ima_event_data *event_data,
 315                             struct ima_field_data *field_data)
 316 {
 317         u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
 318         u32 cur_digestsize = 0;
 319 
 320         if (event_data->violation)      /* recording a violation. */
 321                 goto out;
 322 
 323         cur_digest = event_data->iint->ima_hash->digest;
 324         cur_digestsize = event_data->iint->ima_hash->length;
 325 
 326         hash_algo = event_data->iint->ima_hash->algo;
 327 out:
 328         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 329                                            hash_algo, field_data);
 330 }
 331 
 332 /*
 333  * This function writes the digest of the file which is expected to match the
 334  * digest contained in the file's appended signature.
 335  */
 336 int ima_eventdigest_modsig_init(struct ima_event_data *event_data,
 337                                 struct ima_field_data *field_data)
 338 {
 339         enum hash_algo hash_algo;
 340         const u8 *cur_digest;
 341         u32 cur_digestsize;
 342 
 343         if (!event_data->modsig)
 344                 return 0;
 345 
 346         if (event_data->violation) {
 347                 /* Recording a violation. */
 348                 hash_algo = HASH_ALGO_SHA1;
 349                 cur_digest = NULL;
 350                 cur_digestsize = 0;
 351         } else {
 352                 int rc;
 353 
 354                 rc = ima_get_modsig_digest(event_data->modsig, &hash_algo,
 355                                            &cur_digest, &cur_digestsize);
 356                 if (rc)
 357                         return rc;
 358                 else if (hash_algo == HASH_ALGO__LAST || cur_digestsize == 0)
 359                         /* There was some error collecting the digest. */
 360                         return -EINVAL;
 361         }
 362 
 363         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 364                                            hash_algo, field_data);
 365 }
 366 
 367 static int ima_eventname_init_common(struct ima_event_data *event_data,
 368                                      struct ima_field_data *field_data,
 369                                      bool size_limit)
 370 {
 371         const char *cur_filename = NULL;
 372         u32 cur_filename_len = 0;
 373 
 374         BUG_ON(event_data->filename == NULL && event_data->file == NULL);
 375 
 376         if (event_data->filename) {
 377                 cur_filename = event_data->filename;
 378                 cur_filename_len = strlen(event_data->filename);
 379 
 380                 if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
 381                         goto out;
 382         }
 383 
 384         if (event_data->file) {
 385                 cur_filename = event_data->file->f_path.dentry->d_name.name;
 386                 cur_filename_len = strlen(cur_filename);
 387         } else
 388                 /*
 389                  * Truncate filename if the latter is too long and
 390                  * the file descriptor is not available.
 391                  */
 392                 cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
 393 out:
 394         return ima_write_template_field_data(cur_filename, cur_filename_len,
 395                                              DATA_FMT_STRING, field_data);
 396 }
 397 
 398 /*
 399  * This function writes the name of an event (with size limit).
 400  */
 401 int ima_eventname_init(struct ima_event_data *event_data,
 402                        struct ima_field_data *field_data)
 403 {
 404         return ima_eventname_init_common(event_data, field_data, true);
 405 }
 406 
 407 /*
 408  * This function writes the name of an event (without size limit).
 409  */
 410 int ima_eventname_ng_init(struct ima_event_data *event_data,
 411                           struct ima_field_data *field_data)
 412 {
 413         return ima_eventname_init_common(event_data, field_data, false);
 414 }
 415 
 416 /*
 417  *  ima_eventsig_init - include the file signature as part of the template data
 418  */
 419 int ima_eventsig_init(struct ima_event_data *event_data,
 420                       struct ima_field_data *field_data)
 421 {
 422         struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
 423 
 424         if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
 425                 return 0;
 426 
 427         return ima_write_template_field_data(xattr_value, event_data->xattr_len,
 428                                              DATA_FMT_HEX, field_data);
 429 }
 430 
 431 /*
 432  *  ima_eventbuf_init - include the buffer(kexec-cmldine) as part of the
 433  *  template data.
 434  */
 435 int ima_eventbuf_init(struct ima_event_data *event_data,
 436                       struct ima_field_data *field_data)
 437 {
 438         if ((!event_data->buf) || (event_data->buf_len == 0))
 439                 return 0;
 440 
 441         return ima_write_template_field_data(event_data->buf,
 442                                              event_data->buf_len, DATA_FMT_HEX,
 443                                              field_data);
 444 }
 445 
 446 /*
 447  *  ima_eventmodsig_init - include the appended file signature as part of the
 448  *  template data
 449  */
 450 int ima_eventmodsig_init(struct ima_event_data *event_data,
 451                          struct ima_field_data *field_data)
 452 {
 453         const void *data;
 454         u32 data_len;
 455         int rc;
 456 
 457         if (!event_data->modsig)
 458                 return 0;
 459 
 460         /*
 461          * modsig is a runtime structure containing pointers. Get its raw data
 462          * instead.
 463          */
 464         rc = ima_get_raw_modsig(event_data->modsig, &data, &data_len);
 465         if (rc)
 466                 return rc;
 467 
 468         return ima_write_template_field_data(data, data_len, DATA_FMT_HEX,
 469                                              field_data);
 470 }