src/shared/condition.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <fnmatch.h>
  23 #include <limits.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <sys/stat.h>
  27 #include <time.h>
  28 #include <unistd.h>
  29
  30 #include "sd-id128.h"
  31
  32 #include "alloc-util.h"
  33 #include "apparmor-util.h"
  34 #include "architecture.h"
  35 #include "audit-util.h"
  36 #include "cap-list.h"
  37 #include "condition.h"
  38 #include "extract-word.h"
  39 #include "fd-util.h"
  40 #include "fileio.h"
  41 #include "glob-util.h"
  42 #include "hostname-util.h"
  43 #include "ima-util.h"
  44 #include "list.h"
  45 #include "macro.h"
  46 #include "mount-util.h"
  47 #include "parse-util.h"
  48 #include "path-util.h"
  49 #include "proc-cmdline.h"
  50 #include "selinux-util.h"
  51 #include "smack-util.h"
  52 #include "stat-util.h"
  53 #include "string-table.h"
  54 #include "string-util.h"
  55 #include "util.h"
  56 #include "virt.h"
  57
  58 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  59         Condition *c;
  60         int r;
  61
  62         assert(type >= 0);
  63         assert(type < _CONDITION_TYPE_MAX);
  64         assert((!parameter) == (type == CONDITION_NULL));
  65
  66         c = new0(Condition, 1);
  67         if (!c)
  68                 return NULL;
  69
  70         c->type = type;
  71         c->trigger = trigger;
  72         c->negate = negate;
  73
  74         r = free_and_strdup(&c->parameter, parameter);
  75         if (r < 0) {
  76                 free(c);
  77                 return NULL;
  78         }
  79
  80         return c;
  81 }
  82
  83 void condition_free(Condition *c) {
  84         assert(c);
  85
  86         free(c->parameter);
  87         free(c);
  88 }
  89
  90 Condition* condition_free_list(Condition *first) {
  91         Condition *c, *n;
  92
  93         LIST_FOREACH_SAFE(conditions, c, n, first)
  94                 condition_free(c);
  95
  96         return NULL;
  97 }
  98
  99 static int condition_test_kernel_command_line(Condition *c) {
 100         _cleanup_free_ char *line = NULL;
 101         const char *p;
 102         bool equal;
 103         int r;
 104
 105         assert(c);
 106         assert(c->parameter);
 107         assert(c->type == CONDITION_KERNEL_COMMAND_LINE);
 108
 109         r = proc_cmdline(&line);
 110         if (r < 0)
 111                 return r;
 112
 113         equal = !!strchr(c->parameter, '=');
 114         p = line;
 115
 116         for (;;) {
 117                 _cleanup_free_ char *word = NULL;
 118                 bool found;
 119
 120                 r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
 121                 if (r < 0)
 122                         return r;
 123                 if (r == 0)
 124                         break;
 125
 126                 if (equal)
 127                         found = streq(word, c->parameter);
 128                 else {
 129                         const char *f;
 130
 131                         f = startswith(word, c->parameter);
 132                         found = f && (*f == '=' || *f == 0);
 133                 }
 134
 135                 if (found)
 136                         return true;
 137         }
 138
 139         return false;
 140 }
 141
 142 static int condition_test_virtualization(Condition *c) {
 143         int b, v;
 144
 145         assert(c);
 146         assert(c->parameter);
 147         assert(c->type == CONDITION_VIRTUALIZATION);
 148
 149         if (streq(c->parameter, "private-users"))
 150                 return running_in_userns();
 151
 152         v = detect_virtualization();
 153         if (v < 0)
 154                 return v;
 155
 156         /* First, compare with yes/no */
 157         b = parse_boolean(c->parameter);
 158         if (b >= 0)
 159                 return b == !!v;
 160
 161         /* Then, compare categorization */
 162         if (streq(c->parameter, "vm"))
 163                 return VIRTUALIZATION_IS_VM(v);
 164
 165         if (streq(c->parameter, "container"))
 166                 return VIRTUALIZATION_IS_CONTAINER(v);
 167
 168         /* Finally compare id */
 169         return v != VIRTUALIZATION_NONE && streq(c->parameter, virtualization_to_string(v));
 170 }
 171
 172 static int condition_test_architecture(Condition *c) {
 173         int a, b;
 174
 175         assert(c);
 176         assert(c->parameter);
 177         assert(c->type == CONDITION_ARCHITECTURE);
 178
 179         a = uname_architecture();
 180         if (a < 0)
 181                 return a;
 182
 183         if (streq(c->parameter, "native"))
 184                 b = native_architecture();
 185         else {
 186                 b = architecture_from_string(c->parameter);
 187                 if (b < 0) /* unknown architecture? Then it's definitely not ours */
 188                         return false;
 189         }
 190
 191         return a == b;
 192 }
 193
 194 static int condition_test_host(Condition *c) {
 195         _cleanup_free_ char *h = NULL;
 196         sd_id128_t x, y;
 197         int r;
 198
 199         assert(c);
 200         assert(c->parameter);
 201         assert(c->type == CONDITION_HOST);
 202
 203         if (sd_id128_from_string(c->parameter, &x) >= 0) {
 204
 205                 r = sd_id128_get_machine(&y);
 206                 if (r < 0)
 207                         return r;
 208
 209                 return sd_id128_equal(x, y);
 210         }
 211
 212         h = gethostname_malloc();
 213         if (!h)
 214                 return -ENOMEM;
 215
 216         return fnmatch(c->parameter, h, FNM_CASEFOLD) == 0;
 217 }
 218
 219 static int condition_test_ac_power(Condition *c) {
 220         int r;
 221
 222         assert(c);
 223         assert(c->parameter);
 224         assert(c->type == CONDITION_AC_POWER);
 225
 226         r = parse_boolean(c->parameter);
 227         if (r < 0)
 228                 return r;
 229
 230         return (on_ac_power() != 0) == !!r;
 231 }
 232
 233 static int condition_test_security(Condition *c) {
 234         assert(c);
 235         assert(c->parameter);
 236         assert(c->type == CONDITION_SECURITY);
 237
 238         if (streq(c->parameter, "selinux"))
 239                 return mac_selinux_have();
 240         if (streq(c->parameter, "smack"))
 241                 return mac_smack_use();
 242         if (streq(c->parameter, "apparmor"))
 243                 return mac_apparmor_use();
 244         if (streq(c->parameter, "audit"))
 245                 return use_audit();
 246         if (streq(c->parameter, "ima"))
 247                 return use_ima();
 248
 249         return false;
 250 }
 251
 252 static int condition_test_capability(Condition *c) {
 253         _cleanup_fclose_ FILE *f = NULL;
 254         int value;
 255         char line[LINE_MAX];
 256         unsigned long long capabilities = -1;
 257
 258         assert(c);
 259         assert(c->parameter);
 260         assert(c->type == CONDITION_CAPABILITY);
 261
 262         /* If it's an invalid capability, we don't have it */
 263         value = capability_from_name(c->parameter);
 264         if (value < 0)
 265                 return -EINVAL;
 266
 267         /* If it's a valid capability we default to assume
 268          * that we have it */
 269
 270         f = fopen("/proc/self/status", "re");
 271         if (!f)
 272                 return -errno;
 273
 274         while (fgets(line, sizeof(line), f)) {
 275                 truncate_nl(line);
 276
 277                 if (startswith(line, "CapBnd:")) {
 278                         (void) sscanf(line+7, "%llx", &capabilities);
 279                         break;
 280                 }
 281         }
 282
 283         return !!(capabilities & (1ULL << value));
 284 }
 285
 286 static int condition_test_needs_update(Condition *c) {
 287         const char *p;
 288         struct stat usr, other;
 289
 290         assert(c);
 291         assert(c->parameter);
 292         assert(c->type == CONDITION_NEEDS_UPDATE);
 293
 294         /* If the file system is read-only we shouldn't suggest an update */
 295         if (path_is_read_only_fs(c->parameter) > 0)
 296                 return false;
 297
 298         /* Any other failure means we should allow the condition to be true,
 299          * so that we rather invoke too many update tools than too
 300          * few. */
 301
 302         if (!path_is_absolute(c->parameter))
 303                 return true;
 304
 305         p = strjoina(c->parameter, "/.updated");
 306         if (lstat(p, &other) < 0)
 307                 return true;
 308
 309         if (lstat("/usr/", &usr) < 0)
 310                 return true;
 311
 312         /*
 313          * First, compare seconds as they are always accurate...
 314          */
 315         if (usr.st_mtim.tv_sec != other.st_mtim.tv_sec)
 316                 return usr.st_mtim.tv_sec > other.st_mtim.tv_sec;
 317
 318         /*
 319          * ...then compare nanoseconds.
 320          *
 321          * A false positive is only possible when /usr's nanoseconds > 0
 322          * (otherwise /usr cannot be strictly newer than the target file)
 323          * AND the target file's nanoseconds == 0
 324          * (otherwise the filesystem supports nsec timestamps, see stat(2)).
 325          */
 326         if (usr.st_mtim.tv_nsec > 0 && other.st_mtim.tv_nsec == 0) {
 327                 _cleanup_free_ char *timestamp_str = NULL;
 328                 uint64_t timestamp;
 329                 int r;
 330
 331                 r = parse_env_file(p, NULL, "TIMESTAMP_NSEC", &timestamp_str, NULL);
 332                 if (r < 0) {
 333                         log_error_errno(r, "Failed to parse timestamp file '%s', using mtime: %m", p);
 334                         return true;
 335                 } else if (r == 0) {
 336                         log_debug("No data in timestamp file '%s', using mtime", p);
 337                         return true;
 338                 }
 339
 340                 r = safe_atou64(timestamp_str, &timestamp);
 341                 if (r < 0) {
 342                         log_error_errno(r, "Failed to parse timestamp value '%s' in file '%s', using mtime: %m", timestamp_str, p);
 343                         return true;
 344                 }
 345
 346                 timespec_store(&other.st_mtim, timestamp);
 347         }
 348
 349         return usr.st_mtim.tv_nsec > other.st_mtim.tv_nsec;
 350 }
 351
 352 static int condition_test_first_boot(Condition *c) {
 353         int r;
 354
 355         assert(c);
 356         assert(c->parameter);
 357         assert(c->type == CONDITION_FIRST_BOOT);
 358
 359         r = parse_boolean(c->parameter);
 360         if (r < 0)
 361                 return r;
 362
 363         return (access("/run/systemd/first-boot", F_OK) >= 0) == !!r;
 364 }
 365
 366 static int condition_test_path_exists(Condition *c) {
 367         assert(c);
 368         assert(c->parameter);
 369         assert(c->type == CONDITION_PATH_EXISTS);
 370
 371         return access(c->parameter, F_OK) >= 0;
 372 }
 373
 374 static int condition_test_path_exists_glob(Condition *c) {
 375         assert(c);
 376         assert(c->parameter);
 377         assert(c->type == CONDITION_PATH_EXISTS_GLOB);
 378
 379         return glob_exists(c->parameter) > 0;
 380 }
 381
 382 static int condition_test_path_is_directory(Condition *c) {
 383         assert(c);
 384         assert(c->parameter);
 385         assert(c->type == CONDITION_PATH_IS_DIRECTORY);
 386
 387         return is_dir(c->parameter, true) > 0;
 388 }
 389
 390 static int condition_test_path_is_symbolic_link(Condition *c) {
 391         assert(c);
 392         assert(c->parameter);
 393         assert(c->type == CONDITION_PATH_IS_SYMBOLIC_LINK);
 394
 395         return is_symlink(c->parameter) > 0;
 396 }
 397
 398 static int condition_test_path_is_mount_point(Condition *c) {
 399         assert(c);
 400         assert(c->parameter);
 401         assert(c->type == CONDITION_PATH_IS_MOUNT_POINT);
 402
 403         return path_is_mount_point(c->parameter, AT_SYMLINK_FOLLOW) > 0;
 404 }
 405
 406 static int condition_test_path_is_read_write(Condition *c) {
 407         assert(c);
 408         assert(c->parameter);
 409         assert(c->type == CONDITION_PATH_IS_READ_WRITE);
 410
 411         return path_is_read_only_fs(c->parameter) <= 0;
 412 }
 413
 414 static int condition_test_directory_not_empty(Condition *c) {
 415         int r;
 416
 417         assert(c);
 418         assert(c->parameter);
 419         assert(c->type == CONDITION_DIRECTORY_NOT_EMPTY);
 420
 421         r = dir_is_empty(c->parameter);
 422         return r <= 0 && r != -ENOENT;
 423 }
 424
 425 static int condition_test_file_not_empty(Condition *c) {
 426         struct stat st;
 427
 428         assert(c);
 429         assert(c->parameter);
 430         assert(c->type == CONDITION_FILE_NOT_EMPTY);
 431
 432         return (stat(c->parameter, &st) >= 0 &&
 433                 S_ISREG(st.st_mode) &&
 434                 st.st_size > 0);
 435 }
 436
 437 static int condition_test_file_is_executable(Condition *c) {
 438         struct stat st;
 439
 440         assert(c);
 441         assert(c->parameter);
 442         assert(c->type == CONDITION_FILE_IS_EXECUTABLE);
 443
 444         return (stat(c->parameter, &st) >= 0 &&
 445                 S_ISREG(st.st_mode) &&
 446                 (st.st_mode & 0111));
 447 }
 448
 449 static int condition_test_null(Condition *c) {
 450         assert(c);
 451         assert(c->type == CONDITION_NULL);
 452
 453         /* Note that during parsing we already evaluate the string and
 454          * store it in c->negate */
 455         return true;
 456 }
 457
 458 int condition_test(Condition *c) {
 459
 460         static int (*const condition_tests[_CONDITION_TYPE_MAX])(Condition *c) = {
 461                 [CONDITION_PATH_EXISTS] = condition_test_path_exists,
 462                 [CONDITION_PATH_EXISTS_GLOB] = condition_test_path_exists_glob,
 463                 [CONDITION_PATH_IS_DIRECTORY] = condition_test_path_is_directory,
 464                 [CONDITION_PATH_IS_SYMBOLIC_LINK] = condition_test_path_is_symbolic_link,
 465                 [CONDITION_PATH_IS_MOUNT_POINT] = condition_test_path_is_mount_point,
 466                 [CONDITION_PATH_IS_READ_WRITE] = condition_test_path_is_read_write,
 467                 [CONDITION_DIRECTORY_NOT_EMPTY] = condition_test_directory_not_empty,
 468                 [CONDITION_FILE_NOT_EMPTY] = condition_test_file_not_empty,
 469                 [CONDITION_FILE_IS_EXECUTABLE] = condition_test_file_is_executable,
 470                 [CONDITION_KERNEL_COMMAND_LINE] = condition_test_kernel_command_line,
 471                 [CONDITION_VIRTUALIZATION] = condition_test_virtualization,
 472                 [CONDITION_SECURITY] = condition_test_security,
 473                 [CONDITION_CAPABILITY] = condition_test_capability,
 474                 [CONDITION_HOST] = condition_test_host,
 475                 [CONDITION_AC_POWER] = condition_test_ac_power,
 476                 [CONDITION_ARCHITECTURE] = condition_test_architecture,
 477                 [CONDITION_NEEDS_UPDATE] = condition_test_needs_update,
 478                 [CONDITION_FIRST_BOOT] = condition_test_first_boot,
 479                 [CONDITION_NULL] = condition_test_null,
 480         };
 481
 482         int r, b;
 483
 484         assert(c);
 485         assert(c->type >= 0);
 486         assert(c->type < _CONDITION_TYPE_MAX);
 487
 488         r = condition_tests[c->type](c);
 489         if (r < 0) {
 490                 c->result = CONDITION_ERROR;
 491                 return r;
 492         }
 493
 494         b = (r > 0) == !c->negate;
 495         c->result = b ? CONDITION_SUCCEEDED : CONDITION_FAILED;
 496         return b;
 497 }
 498
 499 void condition_dump(Condition *c, FILE *f, const char *prefix, const char *(*to_string)(ConditionType t)) {
 500         assert(c);
 501         assert(f);
 502
 503         if (!prefix)
 504                 prefix = "";
 505
 506         fprintf(f,
 507                 "%s\t%s: %s%s%s %s\n",
 508                 prefix,
 509                 to_string(c->type),
 510                 c->trigger ? "|" : "",
 511                 c->negate ? "!" : "",
 512                 c->parameter,
 513                 condition_result_to_string(c->result));
 514 }
 515
 516 void condition_dump_list(Condition *first, FILE *f, const char *prefix, const char *(*to_string)(ConditionType t)) {
 517         Condition *c;
 518
 519         LIST_FOREACH(conditions, c, first)
 520                 condition_dump(c, f, prefix, to_string);
 521 }
 522
 523 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 524         [CONDITION_ARCHITECTURE] = "ConditionArchitecture",
 525         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 526         [CONDITION_HOST] = "ConditionHost",
 527         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 528         [CONDITION_SECURITY] = "ConditionSecurity",
 529         [CONDITION_CAPABILITY] = "ConditionCapability",
 530         [CONDITION_AC_POWER] = "ConditionACPower",
 531         [CONDITION_NEEDS_UPDATE] = "ConditionNeedsUpdate",
 532         [CONDITION_FIRST_BOOT] = "ConditionFirstBoot",
 533         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 534         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 535         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 536         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
 537         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
 538         [CONDITION_PATH_IS_READ_WRITE] = "ConditionPathIsReadWrite",
 539         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 540         [CONDITION_FILE_NOT_EMPTY] = "ConditionFileNotEmpty",
 541         [CONDITION_FILE_IS_EXECUTABLE] = "ConditionFileIsExecutable",
 542         [CONDITION_NULL] = "ConditionNull"
 543 };
 544
 545 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);
 546
 547 static const char* const assert_type_table[_CONDITION_TYPE_MAX] = {
 548         [CONDITION_ARCHITECTURE] = "AssertArchitecture",
 549         [CONDITION_VIRTUALIZATION] = "AssertVirtualization",
 550         [CONDITION_HOST] = "AssertHost",
 551         [CONDITION_KERNEL_COMMAND_LINE] = "AssertKernelCommandLine",
 552         [CONDITION_SECURITY] = "AssertSecurity",
 553         [CONDITION_CAPABILITY] = "AssertCapability",
 554         [CONDITION_AC_POWER] = "AssertACPower",
 555         [CONDITION_NEEDS_UPDATE] = "AssertNeedsUpdate",
 556         [CONDITION_FIRST_BOOT] = "AssertFirstBoot",
 557         [CONDITION_PATH_EXISTS] = "AssertPathExists",
 558         [CONDITION_PATH_EXISTS_GLOB] = "AssertPathExistsGlob",
 559         [CONDITION_PATH_IS_DIRECTORY] = "AssertPathIsDirectory",
 560         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "AssertPathIsSymbolicLink",
 561         [CONDITION_PATH_IS_MOUNT_POINT] = "AssertPathIsMountPoint",
 562         [CONDITION_PATH_IS_READ_WRITE] = "AssertPathIsReadWrite",
 563         [CONDITION_DIRECTORY_NOT_EMPTY] = "AssertDirectoryNotEmpty",
 564         [CONDITION_FILE_NOT_EMPTY] = "AssertFileNotEmpty",
 565         [CONDITION_FILE_IS_EXECUTABLE] = "AssertFileIsExecutable",
 566         [CONDITION_NULL] = "AssertNull"
 567 };
 568
 569 DEFINE_STRING_TABLE_LOOKUP(assert_type, ConditionType);
 570
 571 static const char* const condition_result_table[_CONDITION_RESULT_MAX] = {
 572         [CONDITION_UNTESTED] = "untested",
 573         [CONDITION_SUCCEEDED] = "succeeded",
 574         [CONDITION_FAILED] = "failed",
 575         [CONDITION_ERROR] = "error",
 576 };
 577
 578 DEFINE_STRING_TABLE_LOOKUP(condition_result, ConditionResult);