src/sysctl/sysctl.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   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 "hashmap.h"
  18 #include "log.h"
  19 #include "main-func.h"
  20 #include "pager.h"
  21 #include "path-util.h"
  22 #include "pretty-print.h"
  23 #include "string-util.h"
  24 #include "strv.h"
  25 #include "sysctl-util.h"
  26
  27 static char **arg_prefixes = NULL;
  28 static bool arg_cat_config = false;
  29 static PagerFlags arg_pager_flags = 0;
  30
  31 STATIC_DESTRUCTOR_REGISTER(arg_prefixes, strv_freep);
  32
  33 typedef struct Option {
  34         char *key;
  35         char *value;
  36         bool ignore_failure;
  37 } Option;
  38
  39 static Option *option_free(Option *o) {
  40         if (!o)
  41                 return NULL;
  42
  43         free(o->key);
  44         free(o->value);
  45
  46         return mfree(o);
  47 }
  48
  49 DEFINE_TRIVIAL_CLEANUP_FUNC(Option*, option_free);
  50 DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(option_hash_ops, char, string_hash_func, string_compare_func, Option, option_free);
  51
  52 static Option *option_new(
  53                 const char *key,
  54                 const char *value,
  55                 bool ignore_failure) {
  56
  57         _cleanup_(option_freep) Option *o = NULL;
  58
  59         assert(key);
  60         assert(value);
  61
  62         o = new(Option, 1);
  63         if (!o)
  64                 return NULL;
  65
  66         *o = (Option) {
  67                 .key = strdup(key),
  68                 .value = strdup(value),
  69                 .ignore_failure = ignore_failure,
  70         };
  71
  72         if (!o->key || !o->value)
  73                 return NULL;
  74
  75         return TAKE_PTR(o);
  76 }
  77
  78 static int apply_all(OrderedHashmap *sysctl_options) {
  79         Option *option;
  80         Iterator i;
  81         int r = 0;
  82
  83         ORDERED_HASHMAP_FOREACH(option, sysctl_options, i) {
  84                 int k;
  85
  86                 k = sysctl_write(option->key, option->value);
  87                 if (k < 0) {
  88                         /* If the sysctl is not available in the kernel or we are running with reduced
  89                          * privileges and cannot write it, then log about the issue, and proceed without
  90                          * failing. (EROFS is treated as a permission problem here, since that's how
  91                          * container managers usually protected their sysctls.) In all other cases log an
  92                          * error and make the tool fail. */
  93
  94                         if (option->ignore_failure || k == -EROFS || ERRNO_IS_PRIVILEGE(k))
  95                                 log_debug_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", option->value, option->key);
  96                         else if (k == -ENOENT)
  97                                 log_info_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", option->value, option->key);
  98                         else {
  99                                 log_error_errno(k, "Couldn't write '%s' to '%s': %m", option->value, option->key);
 100                                 if (r == 0)
 101                                         r = k;
 102                         }
 103                 }
 104         }
 105
 106         return r;
 107 }
 108
 109 static bool test_prefix(const char *p) {
 110         char **i;
 111
 112         if (strv_isempty(arg_prefixes))
 113                 return true;
 114
 115         STRV_FOREACH(i, arg_prefixes) {
 116                 const char *t;
 117
 118                 t = path_startswith(*i, "/proc/sys/");
 119                 if (!t)
 120                         t = *i;
 121                 if (path_startswith(p, t))
 122                         return true;
 123         }
 124
 125         return false;
 126 }
 127
 128 static int parse_file(OrderedHashmap **sysctl_options, const char *path, bool ignore_enoent) {
 129         _cleanup_fclose_ FILE *f = NULL;
 130         unsigned c = 0;
 131         int r;
 132
 133         assert(path);
 134
 135         r = search_and_fopen(path, "re", NULL, (const char**) CONF_PATHS_STRV("sysctl.d"), &f);
 136         if (r < 0) {
 137                 if (ignore_enoent && r == -ENOENT)
 138                         return 0;
 139
 140                 return log_error_errno(r, "Failed to open file '%s', ignoring: %m", path);
 141         }
 142
 143         log_debug("Parsing %s", path);
 144         for (;;) {
 145                 _cleanup_(option_freep) Option *new_option = NULL;
 146                 _cleanup_free_ char *l = NULL;
 147                 bool ignore_failure;
 148                 Option *existing;
 149                 char *p, *value;
 150                 int k;
 151
 152                 k = read_line(f, LONG_LINE_MAX, &l);
 153                 if (k == 0)
 154                         break;
 155                 if (k < 0)
 156                         return log_error_errno(k, "Failed to read file '%s', ignoring: %m", path);
 157
 158                 c++;
 159
 160                 p = strstrip(l);
 161
 162                 if (isempty(p))
 163                         continue;
 164                 if (strchr(COMMENTS "\n", *p))
 165                         continue;
 166
 167                 value = strchr(p, '=');
 168                 if (!value) {
 169                         log_syntax(NULL, LOG_WARNING, path, c, 0, "Line is not an assignment, ignoring: %s", p);
 170                         if (r == 0)
 171                                 r = -EINVAL;
 172                         continue;
 173                 }
 174
 175                 *value = 0;
 176                 value++;
 177
 178                 p = strstrip(p);
 179                 ignore_failure = p[0] == '-';
 180                 if (ignore_failure)
 181                         p++;
 182
 183                 p = sysctl_normalize(p);
 184                 value = strstrip(value);
 185
 186                 if (!test_prefix(p))
 187                         continue;
 188
 189                 if (ordered_hashmap_ensure_allocated(sysctl_options, &option_hash_ops) < 0)
 190                         return log_oom();
 191
 192                 existing = ordered_hashmap_get(*sysctl_options, p);
 193                 if (existing) {
 194                         if (streq(value, existing->value)) {
 195                                 existing->ignore_failure = existing->ignore_failure || ignore_failure;
 196                                 continue;
 197                         }
 198
 199                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
 200                         option_free(ordered_hashmap_remove(*sysctl_options, p));
 201                 }
 202
 203                 new_option = option_new(p, value, ignore_failure);
 204                 if (!new_option)
 205                         return log_oom();
 206
 207                 k = ordered_hashmap_put(*sysctl_options, new_option->key, new_option);
 208                 if (k < 0)
 209                         return log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", p);
 210
 211                 TAKE_PTR(new_option);
 212         }
 213
 214         return r;
 215 }
 216
 217 static int help(void) {
 218         _cleanup_free_ char *link = NULL;
 219         int r;
 220
 221         r = terminal_urlify_man("systemd-sysctl.service", "8", &link);
 222         if (r < 0)
 223                 return log_oom();
 224
 225         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 226                "Applies kernel sysctl settings.\n\n"
 227                "  -h --help             Show this help\n"
 228                "     --version          Show package version\n"
 229                "     --cat-config       Show configuration files\n"
 230                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 231                "     --no-pager         Do not pipe output into a pager\n"
 232                "\nSee the %s for details.\n"
 233                , program_invocation_short_name
 234                , link
 235         );
 236
 237         return 0;
 238 }
 239
 240 static int parse_argv(int argc, char *argv[]) {
 241
 242         enum {
 243                 ARG_VERSION = 0x100,
 244                 ARG_CAT_CONFIG,
 245                 ARG_PREFIX,
 246                 ARG_NO_PAGER,
 247         };
 248
 249         static const struct option options[] = {
 250                 { "help",       no_argument,       NULL, 'h'            },
 251                 { "version",    no_argument,       NULL, ARG_VERSION    },
 252                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 253                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 254                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
 255                 {}
 256         };
 257
 258         int c;
 259
 260         assert(argc >= 0);
 261         assert(argv);
 262
 263         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 264
 265                 switch (c) {
 266
 267                 case 'h':
 268                         return help();
 269
 270                 case ARG_VERSION:
 271                         return version();
 272
 273                 case ARG_CAT_CONFIG:
 274                         arg_cat_config = true;
 275                         break;
 276
 277                 case ARG_PREFIX: {
 278                         char *p;
 279
 280                         /* We used to require people to specify absolute paths
 281                          * in /proc/sys in the past. This is kinda useless, but
 282                          * we need to keep compatibility. We now support any
 283                          * sysctl name available. */
 284                         sysctl_normalize(optarg);
 285
 286                         if (path_startswith(optarg, "/proc/sys"))
 287                                 p = strdup(optarg);
 288                         else
 289                                 p = path_join("/proc/sys", optarg);
 290                         if (!p)
 291                                 return log_oom();
 292
 293                         if (strv_consume(&arg_prefixes, p) < 0)
 294                                 return log_oom();
 295
 296                         break;
 297                 }
 298
 299                 case ARG_NO_PAGER:
 300                         arg_pager_flags |= PAGER_DISABLE;
 301                         break;
 302
 303                 case '?':
 304                         return -EINVAL;
 305
 306                 default:
 307                         assert_not_reached("Unhandled option");
 308                 }
 309
 310         if (arg_cat_config && argc > optind)
 311                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 312                                        "Positional arguments are not allowed with --cat-config");
 313
 314         return 1;
 315 }
 316
 317 static int run(int argc, char *argv[]) {
 318         _cleanup_(ordered_hashmap_freep) OrderedHashmap *sysctl_options = NULL;
 319         int r, k;
 320
 321         r = parse_argv(argc, argv);
 322         if (r <= 0)
 323                 return r;
 324
 325         log_setup_service();
 326
 327         umask(0022);
 328
 329         if (argc > optind) {
 330                 int i;
 331
 332                 r = 0;
 333
 334                 for (i = optind; i < argc; i++) {
 335                         k = parse_file(&sysctl_options, argv[i], false);
 336                         if (k < 0 && r == 0)
 337                                 r = k;
 338                 }
 339         } else {
 340                 _cleanup_strv_free_ char **files = NULL;
 341                 char **f;
 342
 343                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 344                 if (r < 0)
 345                         return log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 346
 347                 if (arg_cat_config) {
 348                         (void) pager_open(arg_pager_flags);
 349
 350                         return cat_files(NULL, files, 0);
 351                 }
 352
 353                 STRV_FOREACH(f, files) {
 354                         k = parse_file(&sysctl_options, *f, true);
 355                         if (k < 0 && r == 0)
 356                                 r = k;
 357                 }
 358         }
 359
 360         k = apply_all(sysctl_options);
 361         if (k < 0 && r == 0)
 362                 r = k;
 363
 364         return r;
 365 }
 366
 367 DEFINE_MAIN_FUNCTION(run);