src/sysctl/sysctl.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <getopt.h>
   5 #include <limits.h>
   6 #include <stdbool.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <sys/stat.h>
  10 #include <sys/types.h>
  11
  12 #include "build.h"
  13 #include "conf-files.h"
  14 #include "constants.h"
  15 #include "creds-util.h"
  16 #include "errno-util.h"
  17 #include "fd-util.h"
  18 #include "fileio.h"
  19 #include "glob-util.h"
  20 #include "hashmap.h"
  21 #include "log.h"
  22 #include "main-func.h"
  23 #include "pager.h"
  24 #include "path-util.h"
  25 #include "pretty-print.h"
  26 #include "string-util.h"
  27 #include "strv.h"
  28 #include "sysctl-util.h"
  29
  30 static char **arg_prefixes = NULL;
  31 static CatFlags arg_cat_flags = CAT_CONFIG_OFF;
  32 static bool arg_strict = false;
  33 static PagerFlags arg_pager_flags = 0;
  34
  35 STATIC_DESTRUCTOR_REGISTER(arg_prefixes, strv_freep);
  36
  37 typedef struct Option {
  38         char *key;
  39         char *value;
  40         bool ignore_failure;
  41 } Option;
  42
  43 static Option *option_free(Option *o) {
  44         if (!o)
  45                 return NULL;
  46
  47         free(o->key);
  48         free(o->value);
  49
  50         return mfree(o);
  51 }
  52
  53 DEFINE_TRIVIAL_CLEANUP_FUNC(Option*, option_free);
  54 DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(option_hash_ops, char, string_hash_func, string_compare_func, Option, option_free);
  55
  56 static bool test_prefix(const char *p) {
  57         if (strv_isempty(arg_prefixes))
  58                 return true;
  59
  60         return path_startswith_strv(p, arg_prefixes);
  61 }
  62
  63 static Option *option_new(
  64                 const char *key,
  65                 const char *value,
  66                 bool ignore_failure) {
  67
  68         _cleanup_(option_freep) Option *o = NULL;
  69
  70         assert(key);
  71
  72         o = new(Option, 1);
  73         if (!o)
  74                 return NULL;
  75
  76         *o = (Option) {
  77                 .key = strdup(key),
  78                 .value = value ? strdup(value) : NULL,
  79                 .ignore_failure = ignore_failure,
  80         };
  81
  82         if (!o->key)
  83                 return NULL;
  84         if (value && !o->value)
  85                 return NULL;
  86
  87         return TAKE_PTR(o);
  88 }
  89
  90 static int sysctl_write_or_warn(const char *key, const char *value, bool ignore_failure, bool ignore_enoent) {
  91         int r;
  92
  93         r = sysctl_write(key, value);
  94         if (r < 0) {
  95                 /* Proceed without failing if ignore_failure is true.
  96                  * If the sysctl is not available in the kernel or we are running with reduced privileges and
  97                  * cannot write it, then log about the issue, and proceed without failing. Unless strict mode
  98                  * (arg_strict = true) is enabled, in which case we should fail. (EROFS is treated as a
  99                  * permission problem here, since that's how container managers usually protected their
 100                  * sysctls.)
 101                  * In all other cases log an error and make the tool fail. */
 102                 if (ignore_failure || (!arg_strict && (r == -EROFS || ERRNO_IS_PRIVILEGE(r))))
 103                         log_debug_errno(r, "Couldn't write '%s' to '%s', ignoring: %m", value, key);
 104                 else if (ignore_enoent && r == -ENOENT)
 105                         log_warning_errno(r, "Couldn't write '%s' to '%s', ignoring: %m", value, key);
 106                 else
 107                         return log_error_errno(r, "Couldn't write '%s' to '%s': %m", value, key);
 108         }
 109
 110         return 0;
 111 }
 112
 113 static int apply_glob_option_with_prefix(OrderedHashmap *sysctl_options, Option *option, const char *prefix) {
 114         _cleanup_strv_free_ char **paths = NULL;
 115         _cleanup_free_ char *pattern = NULL;
 116         int r;
 117
 118         assert(sysctl_options);
 119         assert(option);
 120
 121         if (prefix) {
 122                 _cleanup_free_ char *key = NULL;
 123
 124                 r = path_glob_can_match(option->key, prefix, &key);
 125                 if (r < 0)
 126                         return log_error_errno(r, "Failed to check if the glob '%s' matches prefix '%s': %m",
 127                                                option->key, prefix);
 128                 if (r == 0) {
 129                         log_debug("The glob '%s' does not match prefix '%s'.", option->key, prefix);
 130                         return 0;
 131                 }
 132
 133                 log_debug("The glob '%s' is prefixed with '%s': '%s'", option->key, prefix, key);
 134
 135                 if (!string_is_glob(key)) {
 136                         /* The prefixed pattern is not glob anymore. Let's skip to call glob(). */
 137                         if (ordered_hashmap_contains(sysctl_options, key)) {
 138                                 log_debug("Not setting %s (explicit setting exists).", key);
 139                                 return 0;
 140                         }
 141
 142                         return sysctl_write_or_warn(key, option->value,
 143                                                     /* ignore_failure = */ option->ignore_failure,
 144                                                     /* ignore_enoent = */ true);
 145                 }
 146
 147                 pattern = path_join("/proc/sys", key);
 148         } else
 149                 pattern = path_join("/proc/sys", option->key);
 150         if (!pattern)
 151                 return log_oom();
 152
 153         r = glob_extend(&paths, pattern, GLOB_NOCHECK);
 154         if (r < 0) {
 155                 if (r == -ENOENT) {
 156                         log_debug("No match for glob: %s", option->key);
 157                         return 0;
 158                 }
 159                 if (option->ignore_failure || ERRNO_IS_PRIVILEGE(r)) {
 160                         log_debug_errno(r, "Failed to resolve glob '%s', ignoring: %m", option->key);
 161                         return 0;
 162                 } else
 163                         return log_error_errno(r, "Couldn't resolve glob '%s': %m", option->key);
 164         }
 165
 166         STRV_FOREACH(s, paths) {
 167                 const char *key;
 168
 169                 assert_se(key = path_startswith(*s, "/proc/sys"));
 170
 171                 if (ordered_hashmap_contains(sysctl_options, key)) {
 172                         log_debug("Not setting %s (explicit setting exists).", key);
 173                         continue;
 174                 }
 175
 176                 RET_GATHER(r,
 177                            sysctl_write_or_warn(key, option->value,
 178                                                 /* ignore_failure = */ option->ignore_failure,
 179                                                 /* ignore_enoent = */ !arg_strict));
 180         }
 181
 182         return r;
 183 }
 184
 185 static int apply_glob_option(OrderedHashmap *sysctl_options, Option *option) {
 186         int r = 0;
 187
 188         if (strv_isempty(arg_prefixes))
 189                 return apply_glob_option_with_prefix(sysctl_options, option, NULL);
 190
 191         STRV_FOREACH(i, arg_prefixes)
 192                 RET_GATHER(r, apply_glob_option_with_prefix(sysctl_options, option, *i));
 193         return r;
 194 }
 195
 196 static int apply_all(OrderedHashmap *sysctl_options) {
 197         Option *option;
 198         int r = 0;
 199
 200         ORDERED_HASHMAP_FOREACH(option, sysctl_options) {
 201                 int k;
 202
 203                 /* Ignore "negative match" options, they are there only to exclude stuff from globs. */
 204                 if (!option->value)
 205                         continue;
 206
 207                 if (string_is_glob(option->key))
 208                         k = apply_glob_option(sysctl_options, option);
 209                 else
 210                         k = sysctl_write_or_warn(option->key, option->value,
 211                                                  /* ignore_failure = */ option->ignore_failure,
 212                                                  /* ignore_enoent = */ !arg_strict);
 213                 RET_GATHER(r, k);
 214         }
 215
 216         return r;
 217 }
 218
 219 static int parse_file(OrderedHashmap **sysctl_options, const char *path, bool ignore_enoent) {
 220         _cleanup_fclose_ FILE *f = NULL;
 221         _cleanup_free_ char *pp = NULL;
 222         unsigned c = 0;
 223         int r;
 224
 225         assert(path);
 226
 227         r = search_and_fopen(path, "re", NULL, (const char**) CONF_PATHS_STRV("sysctl.d"), &f, &pp);
 228         if (r < 0) {
 229                 if (ignore_enoent && r == -ENOENT)
 230                         return 0;
 231
 232                 return log_error_errno(r, "Failed to open file '%s', ignoring: %m", path);
 233         }
 234
 235         log_debug("Parsing %s", pp);
 236         for (;;) {
 237                 _cleanup_(option_freep) Option *new_option = NULL;
 238                 _cleanup_free_ char *l = NULL;
 239                 bool ignore_failure = false;
 240                 Option *existing;
 241                 char *value;
 242                 int k;
 243
 244                 k = read_stripped_line(f, LONG_LINE_MAX, &l);
 245                 if (k == 0)
 246                         break;
 247                 if (k < 0)
 248                         return log_error_errno(k, "Failed to read file '%s', ignoring: %m", pp);
 249
 250                 c++;
 251
 252                 if (isempty(l))
 253                         continue;
 254                 if (strchr(COMMENTS, l[0]))
 255                         continue;
 256
 257                 char *p = l;
 258                 value = strchr(p, '=');
 259                 if (value) {
 260                         if (p[0] == '-') {
 261                                 ignore_failure = true;
 262                                 p++;
 263                         }
 264
 265                         *value = 0;
 266                         value++;
 267                         value = strstrip(value);
 268
 269                 } else {
 270                         if (p[0] == '-')
 271                                 /* We have a "negative match" option. Let's continue with value==NULL. */
 272                                 p++;
 273                         else {
 274                                 log_syntax(NULL, LOG_WARNING, pp, c, 0,
 275                                            "Line is not an assignment, ignoring: %s", p);
 276                                 if (r == 0)
 277                                         r = -EINVAL;
 278                                 continue;
 279                         }
 280                 }
 281
 282                 p = strstrip(p);
 283                 p = sysctl_normalize(p);
 284
 285                 /* We can't filter out globs at this point, we'll need to do that later. */
 286                 if (!string_is_glob(p) &&
 287                     !test_prefix(p))
 288                         continue;
 289
 290                 existing = ordered_hashmap_get(*sysctl_options, p);
 291                 if (existing) {
 292                         if (streq_ptr(value, existing->value)) {
 293                                 existing->ignore_failure = existing->ignore_failure || ignore_failure;
 294                                 continue;
 295                         }
 296
 297                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, pp, c);
 298                         option_free(ordered_hashmap_remove(*sysctl_options, p));
 299                 }
 300
 301                 new_option = option_new(p, value, ignore_failure);
 302                 if (!new_option)
 303                         return log_oom();
 304
 305                 k = ordered_hashmap_ensure_put(sysctl_options, &option_hash_ops, new_option->key, new_option);
 306                 if (k < 0)
 307                         return log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", p);
 308
 309                 TAKE_PTR(new_option);
 310         }
 311
 312         return r;
 313 }
 314
 315 static int read_credential_lines(OrderedHashmap **sysctl_options) {
 316         _cleanup_free_ char *j = NULL;
 317         const char *d;
 318         int r;
 319
 320         r = get_credentials_dir(&d);
 321         if (r == -ENXIO)
 322                 return 0;
 323         if (r < 0)
 324                 return log_error_errno(r, "Failed to get credentials directory: %m");
 325
 326         j = path_join(d, "sysctl.extra");
 327         if (!j)
 328                 return log_oom();
 329
 330         (void) parse_file(sysctl_options, j, /* ignore_enoent= */ true);
 331         return 0;
 332 }
 333
 334 static int cat_config(char **files) {
 335         pager_open(arg_pager_flags);
 336
 337         return cat_files(NULL, files, arg_cat_flags);
 338 }
 339
 340 static int help(void) {
 341         _cleanup_free_ char *link = NULL;
 342         int r;
 343
 344         r = terminal_urlify_man("systemd-sysctl.service", "8", &link);
 345         if (r < 0)
 346                 return log_oom();
 347
 348         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 349                "Applies kernel sysctl settings.\n\n"
 350                "  -h --help             Show this help\n"
 351                "     --version          Show package version\n"
 352                "     --cat-config       Show configuration files\n"
 353                "     --tldr             Show non-comment parts of configuration\n"
 354                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 355                "     --no-pager         Do not pipe output into a pager\n"
 356                "\nSee the %s for details.\n",
 357                program_invocation_short_name,
 358                link);
 359
 360         return 0;
 361 }
 362
 363 static int parse_argv(int argc, char *argv[]) {
 364
 365         enum {
 366                 ARG_VERSION = 0x100,
 367                 ARG_CAT_CONFIG,
 368                 ARG_TLDR,
 369                 ARG_PREFIX,
 370                 ARG_NO_PAGER,
 371                 ARG_STRICT,
 372         };
 373
 374         static const struct option options[] = {
 375                 { "help",       no_argument,       NULL, 'h'            },
 376                 { "version",    no_argument,       NULL, ARG_VERSION    },
 377                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 378                 { "tldr",       no_argument,       NULL, ARG_TLDR       },
 379                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 380                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
 381                 { "strict",     no_argument,       NULL, ARG_STRICT     },
 382                 {}
 383         };
 384
 385         int c;
 386
 387         assert(argc >= 0);
 388         assert(argv);
 389
 390         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 391
 392                 switch (c) {
 393
 394                 case 'h':
 395                         return help();
 396
 397                 case ARG_VERSION:
 398                         return version();
 399
 400                 case ARG_CAT_CONFIG:
 401                         arg_cat_flags = CAT_CONFIG_ON;
 402                         break;
 403
 404                 case ARG_TLDR:
 405                         arg_cat_flags = CAT_TLDR;
 406                         break;
 407
 408                 case ARG_PREFIX: {
 409                         const char *s;
 410                         char *p;
 411
 412                         /* We used to require people to specify absolute paths
 413                          * in /proc/sys in the past. This is kinda useless, but
 414                          * we need to keep compatibility. We now support any
 415                          * sysctl name available. */
 416                         sysctl_normalize(optarg);
 417
 418                         s = path_startswith(optarg, "/proc/sys");
 419                         p = strdup(s ?: optarg);
 420                         if (!p)
 421                                 return log_oom();
 422
 423                         if (strv_consume(&arg_prefixes, p) < 0)
 424                                 return log_oom();
 425
 426                         break;
 427                 }
 428
 429                 case ARG_NO_PAGER:
 430                         arg_pager_flags |= PAGER_DISABLE;
 431                         break;
 432
 433                 case ARG_STRICT:
 434                         arg_strict = true;
 435                         break;
 436
 437                 case '?':
 438                         return -EINVAL;
 439
 440                 default:
 441                         assert_not_reached();
 442                 }
 443
 444         if (arg_cat_flags != CAT_CONFIG_OFF && argc > optind)
 445                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 446                                        "Positional arguments are not allowed with --cat-config/--tldr.");
 447
 448         return 1;
 449 }
 450
 451 static int run(int argc, char *argv[]) {
 452         _cleanup_ordered_hashmap_free_ OrderedHashmap *sysctl_options = NULL;
 453         int r;
 454
 455         r = parse_argv(argc, argv);
 456         if (r <= 0)
 457                 return r;
 458
 459         log_setup();
 460
 461         umask(0022);
 462
 463         if (argc > optind) {
 464                 r = 0;
 465
 466                 for (int i = optind; i < argc; i++)
 467                         RET_GATHER(r, parse_file(&sysctl_options, argv[i], false));
 468
 469         } else {
 470                 _cleanup_strv_free_ char **files = NULL;
 471
 472                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 473                 if (r < 0)
 474                         return log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 475
 476                 if (arg_cat_flags != CAT_CONFIG_OFF)
 477                         return cat_config(files);
 478
 479                 STRV_FOREACH(f, files)
 480                         RET_GATHER(r, parse_file(&sysctl_options, *f, true));
 481
 482                 RET_GATHER(r, read_credential_lines(&sysctl_options));
 483         }
 484
 485         RET_GATHER(r, apply_all(sysctl_options));
 486
 487         return r;
 488 }
 489
 490 DEFINE_MAIN_FUNCTION(run);