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