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
 115         for (p = line;;) {
 116                 _cleanup_free_ char *word = NULL;
 117                 bool found;
 118
 119                 r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
 120                 if (r < 0)
 121                         return r;
 122                 if (r == 0)
 123                         break;
 124
 125                 if (equal)
 126                         found = streq(word, c->parameter);
 127                 else {
 128                         const char *f;
 129
 130                         f = startswith(word, c->parameter);
 131                         found = f && (*f == '=' || *f == 0);
 132                 }
 133
 134                 if (found)
 135                         return true;
 136         }
 137
 138         return false;
 139 }
 140
 141 static int condition_test_virtualization(Condition *c) {
 142         int b, v;
 143
 144         assert(c);
 145         assert(c->parameter);
 146         assert(c->type == CONDITION_VIRTUALIZATION);
 147
 148         if (streq(c->parameter, "private-users"))
 149                 return running_in_userns();
 150
 151         v = detect_virtualization();
 152         if (v < 0)
 153                 return v;
 154
 155         /* First, compare with yes/no */
 156         b = parse_boolean(c->parameter);
 157         if (b >= 0)
 158                 return b == !!v;
 159
 160         /* Then, compare categorization */
 161         if (streq(c->parameter, "vm"))
 162                 return VIRTUALIZATION_IS_VM(v);
 163
 164         if (streq(c->parameter, "container"))
 165                 return VIRTUALIZATION_IS_CONTAINER(v);
 166
 167         /* Finally compare id */
 168         return v != VIRTUALIZATION_NONE && streq(c->parameter, virtualization_to_string(v));
 169 }
 170
 171 static int condition_test_architecture(Condition *c) {
 172         int a, b;
 173
 174         assert(c);
 175         assert(c->parameter);
 176         assert(c->type == CONDITION_ARCHITECTURE);
 177
 178         a = uname_architecture();
 179         if (a < 0)
 180                 return a;
 181
 182         if (streq(c->parameter, "native"))
 183                 b = native_architecture();
 184         else {
 185                 b = architecture_from_string(c->parameter);
 186                 if (b < 0) /* unknown architecture? Then it's definitely not ours */
 187                         return false;
 188         }
 189
 190         return a == b;
 191 }
 192
 193 static int condition_test_host(Condition *c) {
 194         _cleanup_free_ char *h = NULL;
 195         sd_id128_t x, y;
 196         int r;
 197
 198         assert(c);
 199         assert(c->parameter);
 200         assert(c->type == CONDITION_HOST);
 201
 202         if (sd_id128_from_string(c->parameter, &x) >= 0) {
 203
 204                 r = sd_id128_get_machine(&y);
 205                 if (r < 0)
 206                         return r;
 207
 208                 return sd_id128_equal(x, y);
 209         }
 210
 211         h = gethostname_malloc();
 212         if (!h)
 213                 return -ENOMEM;
 214
 215         return fnmatch(c->parameter, h, FNM_CASEFOLD) == 0;
 216 }
 217
 218 static int condition_test_ac_power(Condition *c) {
 219         int r;
 220
 221         assert(c);
 222         assert(c->parameter);
 223         assert(c->type == CONDITION_AC_POWER);
 224
 225         r = parse_boolean(c->parameter);
 226         if (r < 0)
 227                 return r;
 228
 229         return (on_ac_power() != 0) == !!r;
 230 }
 231
 232 static int condition_test_security(Condition *c) {
 233         assert(c);
 234         assert(c->parameter);
 235         assert(c->type == CONDITION_SECURITY);
 236
 237         if (streq(c->parameter, "selinux"))
 238                 return mac_selinux_have();
 239         if (streq(c->parameter, "smack"))
 240                 return mac_smack_use();
 241         if (streq(c->parameter, "apparmor"))
 242                 return mac_apparmor_use();
 243         if (streq(c->parameter, "audit"))
 244                 return use_audit();
 245         if (streq(c->parameter, "ima"))
 246                 return use_ima();
 247
 248         return false;
 249 }
 250
 251 static int condition_test_capability(Condition *c) {
 252         _cleanup_fclose_ FILE *f = NULL;
 253         int value;
 254         char line[LINE_MAX];
 255         unsigned long long capabilities = -1;
 256
 257         assert(c);
 258         assert(c->parameter);
 259         assert(c->type == CONDITION_CAPABILITY);
 260
 261         /* If it's an invalid capability, we don't have it */
 262         value = capability_from_name(c->parameter);
 263         if (value < 0)
 264                 return -EINVAL;
 265
 266         /* If it's a valid capability we default to assume
 267          * that we have it */
 268
 269         f = fopen("/proc/self/status", "re");
 270         if (!f)
 271                 return -errno;
 272
 273         while (fgets(line, sizeof(line), f)) {
 274                 truncate_nl(line);
 275
 276                 if (startswith(line, "CapBnd:")) {
 277                         (void) sscanf(line+7, "%llx", &capabilities);
 278                         break;
 279                 }
 280         }
 281
 282         return !!(capabilities & (1ULL << value));
 283 }
 284
 285 static int condition_test_needs_update(Condition *c) {
 286         const char *p;
 287         struct stat usr, other;
 288
 289         assert(c);
 290         assert(c->parameter);
 291         assert(c->type == CONDITION_NEEDS_UPDATE);
 292
 293         /* If the file system is read-only we shouldn't suggest an update */
 294         if (path_is_read_only_fs(c->parameter) > 0)
 295                 return false;
 296
 297         /* Any other failure means we should allow the condition to be true,
 298          * so that we rather invoke too many update tools than too
 299          * few. */
 300
 301         if (!path_is_absolute(c->parameter))
 302                 return true;
 303
 304         p = strjoina(c->parameter, "/.updated");
 305         if (lstat(p, &other) < 0)
 306                 return true;
 307
 308         if (lstat("/usr/", &usr) < 0)
 309                 return true;
 310
 311         /*
 312          * First, compare seconds as they are always accurate...
 313          */
 314         if (usr.st_mtim.tv_sec != other.st_mtim.tv_sec)
 315                 return usr.st_mtim.tv_sec > other.st_mtim.tv_sec;
 316
 317         /*
 318          * ...then compare nanoseconds.
 319          *
 320          * A false positive is only possible when /usr's nanoseconds > 0
 321          * (otherwise /usr cannot be strictly newer than the target file)
 322          * AND the target file's nanoseconds == 0
 323          * (otherwise the filesystem supports nsec timestamps, see stat(2)).
 324          */
 325         if (usr.st_mtim.tv_nsec > 0 && other.st_mtim.tv_nsec == 0) {
 326                 _cleanup_free_ char *timestamp_str = NULL;
 327                 uint64_t timestamp;
 328                 int r;
 329
 330                 r = parse_env_file(p, NULL, "TIMESTAMP_NSEC", &timestamp_str, NULL);
 331                 if (r < 0) {
 332                         log_error_errno(r, "Failed to parse timestamp file '%s', using mtime: %m", p);
 333                         return true;
 334                 } else if (r == 0) {
 335                         log_debug("No data in timestamp file '%s', using mtime", p);
 336                         return true;
 337                 }
 338
 339                 r = safe_atou64(timestamp_str, &timestamp);
 340                 if (r < 0) {
 341                         log_error_errno(r, "Failed to parse timestamp value '%s' in file '%s', using mtime: %m", timestamp_str, p);
 342                         return true;
 343                 }
 344
 345                 timespec_store(&other.st_mtim, timestamp);
 346         }
 347
 348         return usr.st_mtim.tv_nsec > other.st_mtim.tv_nsec;
 349 }
 350
 351 static int condition_test_first_boot(Condition *c) {
 352         int r;
 353
 354         assert(c);
 355         assert(c->parameter);
 356         assert(c->type == CONDITION_FIRST_BOOT);
 357
 358         r = parse_boolean(c->parameter);
 359         if (r < 0)
 360                 return r;
 361
 362         return (access("/run/systemd/first-boot", F_OK) >= 0) == !!r;
 363 }
 364
 365 static int condition_test_path_exists(Condition *c) {
 366         assert(c);
 367         assert(c->parameter);
 368         assert(c->type == CONDITION_PATH_EXISTS);
 369
 370         return access(c->parameter, F_OK) >= 0;
 371 }
 372
 373 static int condition_test_path_exists_glob(Condition *c) {
 374         assert(c);
 375         assert(c->parameter);
 376         assert(c->type == CONDITION_PATH_EXISTS_GLOB);
 377
 378         return glob_exists(c->parameter) > 0;
 379 }
 380
 381 static int condition_test_path_is_directory(Condition *c) {
 382         assert(c);
 383         assert(c->parameter);
 384         assert(c->type == CONDITION_PATH_IS_DIRECTORY);
 385
 386         return is_dir(c->parameter, true) > 0;
 387 }
 388
 389 static int condition_test_path_is_symbolic_link(Condition *c) {
 390         assert(c);
 391         assert(c->parameter);
 392         assert(c->type == CONDITION_PATH_IS_SYMBOLIC_LINK);
 393
 394         return is_symlink(c->parameter) > 0;
 395 }
 396
 397 static int condition_test_path_is_mount_point(Condition *c) {
 398         assert(c);
 399         assert(c->parameter);
 400         assert(c->type == CONDITION_PATH_IS_MOUNT_POINT);
 401
 402         return path_is_mount_point(c->parameter, AT_SYMLINK_FOLLOW) > 0;
 403 }
 404
 405 static int condition_test_path_is_read_write(Condition *c) {
 406         assert(c);
 407         assert(c->parameter);
 408         assert(c->type == CONDITION_PATH_IS_READ_WRITE);
 409
 410         return path_is_read_only_fs(c->parameter) <= 0;
 411 }
 412
 413 static int condition_test_directory_not_empty(Condition *c) {
 414         int r;
 415
 416         assert(c);
 417         assert(c->parameter);
 418         assert(c->type == CONDITION_DIRECTORY_NOT_EMPTY);
 419
 420         r = dir_is_empty(c->parameter);
 421         return r <= 0 && r != -ENOENT;
 422 }
 423
 424 static int condition_test_file_not_empty(Condition *c) {
 425         struct stat st;
 426
 427         assert(c);
 428         assert(c->parameter);
 429         assert(c->type == CONDITION_FILE_NOT_EMPTY);
 430
 431         return (stat(c->parameter, &st) >= 0 &&
 432                 S_ISREG(st.st_mode) &&
 433                 st.st_size > 0);
 434 }
 435
 436 static int condition_test_file_is_executable(Condition *c) {
 437         struct stat st;
 438
 439         assert(c);
 440         assert(c->parameter);
 441         assert(c->type == CONDITION_FILE_IS_EXECUTABLE);
 442
 443         return (stat(c->parameter, &st) >= 0 &&
 444                 S_ISREG(st.st_mode) &&
 445                 (st.st_mode & 0111));
 446 }
 447
 448 static int condition_test_null(Condition *c) {
 449         assert(c);
 450         assert(c->type == CONDITION_NULL);
 451
 452         /* Note that during parsing we already evaluate the string and
 453          * store it in c->negate */
 454         return true;
 455 }
 456
 457 int condition_test(Condition *c) {
 458
 459         static int (*const condition_tests[_CONDITION_TYPE_MAX])(Condition *c) = {
 460                 [CONDITION_PATH_EXISTS] = condition_test_path_exists,
 461                 [CONDITION_PATH_EXISTS_GLOB] = condition_test_path_exists_glob,
 462                 [CONDITION_PATH_IS_DIRECTORY] = condition_test_path_is_directory,
 463                 [CONDITION_PATH_IS_SYMBOLIC_LINK] = condition_test_path_is_symbolic_link,
 464                 [CONDITION_PATH_IS_MOUNT_POINT] = condition_test_path_is_mount_point,
 465                 [CONDITION_PATH_IS_READ_WRITE] = condition_test_path_is_read_write,
 466                 [CONDITION_DIRECTORY_NOT_EMPTY] = condition_test_directory_not_empty,
 467                 [CONDITION_FILE_NOT_EMPTY] = condition_test_file_not_empty,
 468                 [CONDITION_FILE_IS_EXECUTABLE] = condition_test_file_is_executable,
 469                 [CONDITION_KERNEL_COMMAND_LINE] = condition_test_kernel_command_line,
 470                 [CONDITION_VIRTUALIZATION] = condition_test_virtualization,
 471                 [CONDITION_SECURITY] = condition_test_security,
 472                 [CONDITION_CAPABILITY] = condition_test_capability,
 473                 [CONDITION_HOST] = condition_test_host,
 474                 [CONDITION_AC_POWER] = condition_test_ac_power,
 475                 [CONDITION_ARCHITECTURE] = condition_test_architecture,
 476                 [CONDITION_NEEDS_UPDATE] = condition_test_needs_update,
 477                 [CONDITION_FIRST_BOOT] = condition_test_first_boot,
 478                 [CONDITION_NULL] = condition_test_null,
 479         };
 480
 481         int r, b;
 482
 483         assert(c);
 484         assert(c->type >= 0);
 485         assert(c->type < _CONDITION_TYPE_MAX);
 486
 487         r = condition_tests[c->type](c);
 488         if (r < 0) {
 489                 c->result = CONDITION_ERROR;
 490                 return r;
 491         }
 492
 493         b = (r > 0) == !c->negate;
 494         c->result = b ? CONDITION_SUCCEEDED : CONDITION_FAILED;
 495         return b;
 496 }
 497
 498 void condition_dump(Condition *c, FILE *f, const char *prefix, const char *(*to_string)(ConditionType t)) {
 499         assert(c);
 500         assert(f);
 501
 502         if (!prefix)
 503                 prefix = "";
 504
 505         fprintf(f,
 506                 "%s\t%s: %s%s%s %s\n",
 507                 prefix,
 508                 to_string(c->type),
 509                 c->trigger ? "|" : "",
 510                 c->negate ? "!" : "",
 511                 c->parameter,
 512                 condition_result_to_string(c->result));
 513 }
 514
 515 void condition_dump_list(Condition *first, FILE *f, const char *prefix, const char *(*to_string)(ConditionType t)) {
 516         Condition *c;
 517
 518         LIST_FOREACH(conditions, c, first)
 519                 condition_dump(c, f, prefix, to_string);
 520 }
 521
 522 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 523         [CONDITION_ARCHITECTURE] = "ConditionArchitecture",
 524         [CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
 525         [CONDITION_HOST] = "ConditionHost",
 526         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 527         [CONDITION_SECURITY] = "ConditionSecurity",
 528         [CONDITION_CAPABILITY] = "ConditionCapability",
 529         [CONDITION_AC_POWER] = "ConditionACPower",
 530         [CONDITION_NEEDS_UPDATE] = "ConditionNeedsUpdate",
 531         [CONDITION_FIRST_BOOT] = "ConditionFirstBoot",
 532         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 533         [CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
 534         [CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
 535         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
 536         [CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
 537         [CONDITION_PATH_IS_READ_WRITE] = "ConditionPathIsReadWrite",
 538         [CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
 539         [CONDITION_FILE_NOT_EMPTY] = "ConditionFileNotEmpty",
 540         [CONDITION_FILE_IS_EXECUTABLE] = "ConditionFileIsExecutable",
 541         [CONDITION_NULL] = "ConditionNull"
 542 };
 543
 544 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);
 545
 546 static const char* const assert_type_table[_CONDITION_TYPE_MAX] = {
 547         [CONDITION_ARCHITECTURE] = "AssertArchitecture",
 548         [CONDITION_VIRTUALIZATION] = "AssertVirtualization",
 549         [CONDITION_HOST] = "AssertHost",
 550         [CONDITION_KERNEL_COMMAND_LINE] = "AssertKernelCommandLine",
 551         [CONDITION_SECURITY] = "AssertSecurity",
 552         [CONDITION_CAPABILITY] = "AssertCapability",
 553         [CONDITION_AC_POWER] = "AssertACPower",
 554         [CONDITION_NEEDS_UPDATE] = "AssertNeedsUpdate",
 555         [CONDITION_FIRST_BOOT] = "AssertFirstBoot",
 556         [CONDITION_PATH_EXISTS] = "AssertPathExists",
 557         [CONDITION_PATH_EXISTS_GLOB] = "AssertPathExistsGlob",
 558         [CONDITION_PATH_IS_DIRECTORY] = "AssertPathIsDirectory",
 559         [CONDITION_PATH_IS_SYMBOLIC_LINK] = "AssertPathIsSymbolicLink",
 560         [CONDITION_PATH_IS_MOUNT_POINT] = "AssertPathIsMountPoint",
 561         [CONDITION_PATH_IS_READ_WRITE] = "AssertPathIsReadWrite",
 562         [CONDITION_DIRECTORY_NOT_EMPTY] = "AssertDirectoryNotEmpty",
 563         [CONDITION_FILE_NOT_EMPTY] = "AssertFileNotEmpty",
 564         [CONDITION_FILE_IS_EXECUTABLE] = "AssertFileIsExecutable",
 565         [CONDITION_NULL] = "AssertNull"
 566 };
 567
 568 DEFINE_STRING_TABLE_LOOKUP(assert_type, ConditionType);
 569
 570 static const char* const condition_result_table[_CONDITION_RESULT_MAX] = {
 571         [CONDITION_UNTESTED] = "untested",
 572         [CONDITION_SUCCEEDED] = "succeeded",
 573         [CONDITION_FAILED] = "failed",
 574         [CONDITION_ERROR] = "error",
 575 };
 576
 577 DEFINE_STRING_TABLE_LOOKUP(condition_result, ConditionResult);