security/integrity/ima/ima_template_lib.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2013 Politecnico di Torino, Italy
   4  *                    TORSEC group -- https://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 #include "ima_template_lib.h"
  13
  14 static bool ima_template_hash_algo_allowed(u8 algo)
  15 {
  16         if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
  17                 return true;
  18
  19         return false;
  20 }
  21
  22 enum data_formats {
  23         DATA_FMT_DIGEST = 0,
  24         DATA_FMT_DIGEST_WITH_ALGO,
  25         DATA_FMT_STRING,
  26         DATA_FMT_HEX
  27 };
  28
  29 static int ima_write_template_field_data(const void *data, const u32 datalen,
  30                                          enum data_formats datafmt,
  31                                          struct ima_field_data *field_data)
  32 {
  33         u8 *buf, *buf_ptr;
  34         u32 buflen = datalen;
  35
  36         if (datafmt == DATA_FMT_STRING)
  37                 buflen = datalen + 1;
  38
  39         buf = kzalloc(buflen, GFP_KERNEL);
  40         if (!buf)
  41                 return -ENOMEM;
  42
  43         memcpy(buf, data, datalen);
  44
  45         /*
  46          * Replace all space characters with underscore for event names and
  47          * strings. This avoid that, during the parsing of a measurements list,
  48          * filenames with spaces or that end with the suffix ' (deleted)' are
  49          * split into multiple template fields (the space is the delimitator
  50          * character for measurements lists in ASCII format).
  51          */
  52         if (datafmt == DATA_FMT_STRING) {
  53                 for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
  54                         if (*buf_ptr == ' ')
  55                                 *buf_ptr = '_';
  56         }
  57
  58         field_data->data = buf;
  59         field_data->len = buflen;
  60         return 0;
  61 }
  62
  63 static void ima_show_template_data_ascii(struct seq_file *m,
  64                                          enum ima_show_type show,
  65                                          enum data_formats datafmt,
  66                                          struct ima_field_data *field_data)
  67 {
  68         u8 *buf_ptr = field_data->data;
  69         u32 buflen = field_data->len;
  70
  71         switch (datafmt) {
  72         case DATA_FMT_DIGEST_WITH_ALGO:
  73                 buf_ptr = strnchr(field_data->data, buflen, ':');
  74                 if (buf_ptr != field_data->data)
  75                         seq_printf(m, "%s", field_data->data);
  76
  77                 /* skip ':' and '\0' */
  78                 buf_ptr += 2;
  79                 buflen -= buf_ptr - field_data->data;
  80                 fallthrough;
  81         case DATA_FMT_DIGEST:
  82         case DATA_FMT_HEX:
  83                 if (!buflen)
  84                         break;
  85                 ima_print_digest(m, buf_ptr, buflen);
  86                 break;
  87         case DATA_FMT_STRING:
  88                 seq_printf(m, "%s", buf_ptr);
  89                 break;
  90         default:
  91                 break;
  92         }
  93 }
  94
  95 static void ima_show_template_data_binary(struct seq_file *m,
  96                                           enum ima_show_type show,
  97                                           enum data_formats datafmt,
  98                                           struct ima_field_data *field_data)
  99 {
 100         u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
 101             strlen(field_data->data) : field_data->len;
 102
 103         if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
 104                 u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
 105
 106                 ima_putc(m, &field_len, sizeof(field_len));
 107         }
 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 void ima_show_template_buf(struct seq_file *m, enum ima_show_type show,
 160                            struct ima_field_data *field_data)
 161 {
 162         ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
 163 }
 164
 165 /**
 166  * ima_parse_buf() - Parses lengths and data from an input buffer
 167  * @bufstartp:       Buffer start address.
 168  * @bufendp:         Buffer end address.
 169  * @bufcurp:         Pointer to remaining (non-parsed) data.
 170  * @maxfields:       Length of fields array.
 171  * @fields:          Array containing lengths and pointers of parsed data.
 172  * @curfields:       Number of array items containing parsed data.
 173  * @len_mask:        Bitmap (if bit is set, data length should not be parsed).
 174  * @enforce_mask:    Check if curfields == maxfields and/or bufcurp == bufendp.
 175  * @bufname:         String identifier of the input buffer.
 176  *
 177  * Return: 0 on success, -EINVAL on error.
 178  */
 179 int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp,
 180                   int maxfields, struct ima_field_data *fields, int *curfields,
 181                   unsigned long *len_mask, int enforce_mask, char *bufname)
 182 {
 183         void *bufp = bufstartp;
 184         int i;
 185
 186         for (i = 0; i < maxfields; i++) {
 187                 if (len_mask == NULL || !test_bit(i, len_mask)) {
 188                         if (bufp > (bufendp - sizeof(u32)))
 189                                 break;
 190
 191                         fields[i].len = *(u32 *)bufp;
 192                         if (ima_canonical_fmt)
 193                                 fields[i].len = le32_to_cpu(fields[i].len);
 194
 195                         bufp += sizeof(u32);
 196                 }
 197
 198                 if (bufp > (bufendp - fields[i].len))
 199                         break;
 200
 201                 fields[i].data = bufp;
 202                 bufp += fields[i].len;
 203         }
 204
 205         if ((enforce_mask & ENFORCE_FIELDS) && i != maxfields) {
 206                 pr_err("%s: nr of fields mismatch: expected: %d, current: %d\n",
 207                        bufname, maxfields, i);
 208                 return -EINVAL;
 209         }
 210
 211         if ((enforce_mask & ENFORCE_BUFEND) && bufp != bufendp) {
 212                 pr_err("%s: buf end mismatch: expected: %p, current: %p\n",
 213                        bufname, bufendp, bufp);
 214                 return -EINVAL;
 215         }
 216
 217         if (curfields)
 218                 *curfields = i;
 219
 220         if (bufcurp)
 221                 *bufcurp = bufp;
 222
 223         return 0;
 224 }
 225
 226 static int ima_eventdigest_init_common(const u8 *digest, u32 digestsize,
 227                                        u8 hash_algo,
 228                                        struct ima_field_data *field_data)
 229 {
 230         /*
 231          * digest formats:
 232          *  - DATA_FMT_DIGEST: digest
 233          *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
 234          *    where <hash algo> is provided if the hash algoritm is not
 235          *    SHA1 or MD5
 236          */
 237         u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
 238         enum data_formats fmt = DATA_FMT_DIGEST;
 239         u32 offset = 0;
 240
 241         if (hash_algo < HASH_ALGO__LAST) {
 242                 fmt = DATA_FMT_DIGEST_WITH_ALGO;
 243                 offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
 244                                    hash_algo_name[hash_algo]);
 245                 buffer[offset] = ':';
 246                 offset += 2;
 247         }
 248
 249         if (digest)
 250                 memcpy(buffer + offset, digest, digestsize);
 251         else
 252                 /*
 253                  * If digest is NULL, the event being recorded is a violation.
 254                  * Make room for the digest by increasing the offset of
 255                  * IMA_DIGEST_SIZE.
 256                  */
 257                 offset += IMA_DIGEST_SIZE;
 258
 259         return ima_write_template_field_data(buffer, offset + digestsize,
 260                                              fmt, field_data);
 261 }
 262
 263 /*
 264  * This function writes the digest of an event (with size limit).
 265  */
 266 int ima_eventdigest_init(struct ima_event_data *event_data,
 267                          struct ima_field_data *field_data)
 268 {
 269         struct {
 270                 struct ima_digest_data hdr;
 271                 char digest[IMA_MAX_DIGEST_SIZE];
 272         } hash;
 273         u8 *cur_digest = NULL;
 274         u32 cur_digestsize = 0;
 275         struct inode *inode;
 276         int result;
 277
 278         memset(&hash, 0, sizeof(hash));
 279
 280         if (event_data->violation)      /* recording a violation. */
 281                 goto out;
 282
 283         if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
 284                 cur_digest = event_data->iint->ima_hash->digest;
 285                 cur_digestsize = event_data->iint->ima_hash->length;
 286                 goto out;
 287         }
 288
 289         if ((const char *)event_data->filename == boot_aggregate_name) {
 290                 if (ima_tpm_chip) {
 291                         hash.hdr.algo = HASH_ALGO_SHA1;
 292                         result = ima_calc_boot_aggregate(&hash.hdr);
 293
 294                         /* algo can change depending on available PCR banks */
 295                         if (!result && hash.hdr.algo != HASH_ALGO_SHA1)
 296                                 result = -EINVAL;
 297
 298                         if (result < 0)
 299                                 memset(&hash, 0, sizeof(hash));
 300                 }
 301
 302                 cur_digest = hash.hdr.digest;
 303                 cur_digestsize = hash_digest_size[HASH_ALGO_SHA1];
 304                 goto out;
 305         }
 306
 307         if (!event_data->file)  /* missing info to re-calculate the digest */
 308                 return -EINVAL;
 309
 310         inode = file_inode(event_data->file);
 311         hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
 312             ima_hash_algo : HASH_ALGO_SHA1;
 313         result = ima_calc_file_hash(event_data->file, &hash.hdr);
 314         if (result) {
 315                 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
 316                                     event_data->filename, "collect_data",
 317                                     "failed", result, 0);
 318                 return result;
 319         }
 320         cur_digest = hash.hdr.digest;
 321         cur_digestsize = hash.hdr.length;
 322 out:
 323         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 324                                            HASH_ALGO__LAST, field_data);
 325 }
 326
 327 /*
 328  * This function writes the digest of an event (without size limit).
 329  */
 330 int ima_eventdigest_ng_init(struct ima_event_data *event_data,
 331                             struct ima_field_data *field_data)
 332 {
 333         u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
 334         u32 cur_digestsize = 0;
 335
 336         if (event_data->violation)      /* recording a violation. */
 337                 goto out;
 338
 339         cur_digest = event_data->iint->ima_hash->digest;
 340         cur_digestsize = event_data->iint->ima_hash->length;
 341
 342         hash_algo = event_data->iint->ima_hash->algo;
 343 out:
 344         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 345                                            hash_algo, field_data);
 346 }
 347
 348 /*
 349  * This function writes the digest of the file which is expected to match the
 350  * digest contained in the file's appended signature.
 351  */
 352 int ima_eventdigest_modsig_init(struct ima_event_data *event_data,
 353                                 struct ima_field_data *field_data)
 354 {
 355         enum hash_algo hash_algo;
 356         const u8 *cur_digest;
 357         u32 cur_digestsize;
 358
 359         if (!event_data->modsig)
 360                 return 0;
 361
 362         if (event_data->violation) {
 363                 /* Recording a violation. */
 364                 hash_algo = HASH_ALGO_SHA1;
 365                 cur_digest = NULL;
 366                 cur_digestsize = 0;
 367         } else {
 368                 int rc;
 369
 370                 rc = ima_get_modsig_digest(event_data->modsig, &hash_algo,
 371                                            &cur_digest, &cur_digestsize);
 372                 if (rc)
 373                         return rc;
 374                 else if (hash_algo == HASH_ALGO__LAST || cur_digestsize == 0)
 375                         /* There was some error collecting the digest. */
 376                         return -EINVAL;
 377         }
 378
 379         return ima_eventdigest_init_common(cur_digest, cur_digestsize,
 380                                            hash_algo, field_data);
 381 }
 382
 383 static int ima_eventname_init_common(struct ima_event_data *event_data,
 384                                      struct ima_field_data *field_data,
 385                                      bool size_limit)
 386 {
 387         const char *cur_filename = NULL;
 388         u32 cur_filename_len = 0;
 389
 390         BUG_ON(event_data->filename == NULL && event_data->file == NULL);
 391
 392         if (event_data->filename) {
 393                 cur_filename = event_data->filename;
 394                 cur_filename_len = strlen(event_data->filename);
 395
 396                 if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
 397                         goto out;
 398         }
 399
 400         if (event_data->file) {
 401                 cur_filename = event_data->file->f_path.dentry->d_name.name;
 402                 cur_filename_len = strlen(cur_filename);
 403         } else
 404                 /*
 405                  * Truncate filename if the latter is too long and
 406                  * the file descriptor is not available.
 407                  */
 408                 cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
 409 out:
 410         return ima_write_template_field_data(cur_filename, cur_filename_len,
 411                                              DATA_FMT_STRING, field_data);
 412 }
 413
 414 /*
 415  * This function writes the name of an event (with size limit).
 416  */
 417 int ima_eventname_init(struct ima_event_data *event_data,
 418                        struct ima_field_data *field_data)
 419 {
 420         return ima_eventname_init_common(event_data, field_data, true);
 421 }
 422
 423 /*
 424  * This function writes the name of an event (without size limit).
 425  */
 426 int ima_eventname_ng_init(struct ima_event_data *event_data,
 427                           struct ima_field_data *field_data)
 428 {
 429         return ima_eventname_init_common(event_data, field_data, false);
 430 }
 431
 432 /*
 433  *  ima_eventsig_init - include the file signature as part of the template data
 434  */
 435 int ima_eventsig_init(struct ima_event_data *event_data,
 436                       struct ima_field_data *field_data)
 437 {
 438         struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
 439
 440         if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
 441                 return 0;
 442
 443         return ima_write_template_field_data(xattr_value, event_data->xattr_len,
 444                                              DATA_FMT_HEX, field_data);
 445 }
 446
 447 /*
 448  *  ima_eventbuf_init - include the buffer(kexec-cmldine) as part of the
 449  *  template data.
 450  */
 451 int ima_eventbuf_init(struct ima_event_data *event_data,
 452                       struct ima_field_data *field_data)
 453 {
 454         if ((!event_data->buf) || (event_data->buf_len == 0))
 455                 return 0;
 456
 457         return ima_write_template_field_data(event_data->buf,
 458                                              event_data->buf_len, DATA_FMT_HEX,
 459                                              field_data);
 460 }
 461
 462 /*
 463  *  ima_eventmodsig_init - include the appended file signature as part of the
 464  *  template data
 465  */
 466 int ima_eventmodsig_init(struct ima_event_data *event_data,
 467                          struct ima_field_data *field_data)
 468 {
 469         const void *data;
 470         u32 data_len;
 471         int rc;
 472
 473         if (!event_data->modsig)
 474                 return 0;
 475
 476         /*
 477          * modsig is a runtime structure containing pointers. Get its raw data
 478          * instead.
 479          */
 480         rc = ima_get_raw_modsig(event_data->modsig, &data, &data_len);
 481         if (rc)
 482                 return rc;
 483
 484         return ima_write_template_field_data(data, data_len, DATA_FMT_HEX,
 485                                              field_data);
 486 }