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