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