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 <string.h>
  10 #include <sys/stat.h>
  11 #include <sys/types.h>
  12
  13 #include "conf-files.h"
  14 #include "def.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 at LOG_NOTICE level, and
  90                          * proceed without failing. (EROFS is treated as a permission problem here, since
  91                          * that's how container managers usually protected their sysctls.) In all other cases
  92                          * log an error and make the tool fail. */
  93
  94                         if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT) || option->ignore_failure)
  95                                 log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", option->value, option->key);
  96                         else {
  97                                 log_error_errno(k, "Couldn't write '%s' to '%s': %m", option->value, option->key);
  98                                 if (r == 0)
  99                                         r = k;
 100                         }
 101                 }
 102         }
 103
 104         return r;
 105 }
 106
 107 static bool test_prefix(const char *p) {
 108         char **i;
 109
 110         if (strv_isempty(arg_prefixes))
 111                 return true;
 112
 113         STRV_FOREACH(i, arg_prefixes) {
 114                 const char *t;
 115
 116                 t = path_startswith(*i, "/proc/sys/");
 117                 if (!t)
 118                         t = *i;
 119                 if (path_startswith(p, t))
 120                         return true;
 121         }
 122
 123         return false;
 124 }
 125
 126 static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ignore_enoent) {
 127         _cleanup_fclose_ FILE *f = NULL;
 128         unsigned c = 0;
 129         int r;
 130
 131         assert(path);
 132
 133         r = search_and_fopen(path, "re", NULL, (const char**) CONF_PATHS_STRV("sysctl.d"), &f);
 134         if (r < 0) {
 135                 if (ignore_enoent && r == -ENOENT)
 136                         return 0;
 137
 138                 return log_error_errno(r, "Failed to open file '%s', ignoring: %m", path);
 139         }
 140
 141         log_debug("Parsing %s", path);
 142         for (;;) {
 143                 _cleanup_(option_freep) Option *new_option = NULL;
 144                 _cleanup_free_ char *l = NULL;
 145                 bool ignore_failure;
 146                 Option *existing;
 147                 char *p, *value;
 148                 int k;
 149
 150                 k = read_line(f, LONG_LINE_MAX, &l);
 151                 if (k == 0)
 152                         break;
 153                 if (k < 0)
 154                         return log_error_errno(k, "Failed to read file '%s', ignoring: %m", path);
 155
 156                 c++;
 157
 158                 p = strstrip(l);
 159
 160                 if (isempty(p))
 161                         continue;
 162                 if (strchr(COMMENTS "\n", *p))
 163                         continue;
 164
 165                 value = strchr(p, '=');
 166                 if (!value) {
 167                         log_syntax(NULL, LOG_WARNING, path, c, 0, "Line is not an assignment, ignoring: %s", p);
 168                         if (r == 0)
 169                                 r = -EINVAL;
 170                         continue;
 171                 }
 172
 173                 *value = 0;
 174                 value++;
 175
 176                 p = strstrip(p);
 177                 ignore_failure = p[0] == '-';
 178                 if (ignore_failure)
 179                         p++;
 180
 181                 p = sysctl_normalize(p);
 182                 value = strstrip(value);
 183
 184                 if (!test_prefix(p))
 185                         continue;
 186
 187                 existing = ordered_hashmap_get(sysctl_options, p);
 188                 if (existing) {
 189                         if (streq(value, existing->value)) {
 190                                 existing->ignore_failure = existing->ignore_failure || ignore_failure;
 191                                 continue;
 192                         }
 193
 194                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
 195                         option_free(ordered_hashmap_remove(sysctl_options, p));
 196                 }
 197
 198                 new_option = option_new(p, value, ignore_failure);
 199                 if (!new_option)
 200                         return log_oom();
 201
 202                 k = ordered_hashmap_put(sysctl_options, new_option->key, new_option);
 203                 if (k < 0)
 204                         return log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", p);
 205
 206                 TAKE_PTR(new_option);
 207         }
 208
 209         return r;
 210 }
 211
 212 static int help(void) {
 213         _cleanup_free_ char *link = NULL;
 214         int r;
 215
 216         r = terminal_urlify_man("systemd-sysctl.service", "8", &link);
 217         if (r < 0)
 218                 return log_oom();
 219
 220         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 221                "Applies kernel sysctl settings.\n\n"
 222                "  -h --help             Show this help\n"
 223                "     --version          Show package version\n"
 224                "     --cat-config       Show configuration files\n"
 225                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 226                "     --no-pager         Do not pipe output into a pager\n"
 227                "\nSee the %s for details.\n"
 228                , program_invocation_short_name
 229                , link
 230         );
 231
 232         return 0;
 233 }
 234
 235 static int parse_argv(int argc, char *argv[]) {
 236
 237         enum {
 238                 ARG_VERSION = 0x100,
 239                 ARG_CAT_CONFIG,
 240                 ARG_PREFIX,
 241                 ARG_NO_PAGER,
 242         };
 243
 244         static const struct option options[] = {
 245                 { "help",       no_argument,       NULL, 'h'            },
 246                 { "version",    no_argument,       NULL, ARG_VERSION    },
 247                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 248                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 249                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
 250                 {}
 251         };
 252
 253         int c;
 254
 255         assert(argc >= 0);
 256         assert(argv);
 257
 258         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 259
 260                 switch (c) {
 261
 262                 case 'h':
 263                         return help();
 264
 265                 case ARG_VERSION:
 266                         return version();
 267
 268                 case ARG_CAT_CONFIG:
 269                         arg_cat_config = true;
 270                         break;
 271
 272                 case ARG_PREFIX: {
 273                         char *p;
 274
 275                         /* We used to require people to specify absolute paths
 276                          * in /proc/sys in the past. This is kinda useless, but
 277                          * we need to keep compatibility. We now support any
 278                          * sysctl name available. */
 279                         sysctl_normalize(optarg);
 280
 281                         if (path_startswith(optarg, "/proc/sys"))
 282                                 p = strdup(optarg);
 283                         else
 284                                 p = path_join("/proc/sys", optarg);
 285                         if (!p)
 286                                 return log_oom();
 287
 288                         if (strv_consume(&arg_prefixes, p) < 0)
 289                                 return log_oom();
 290
 291                         break;
 292                 }
 293
 294                 case ARG_NO_PAGER:
 295                         arg_pager_flags |= PAGER_DISABLE;
 296                         break;
 297
 298                 case '?':
 299                         return -EINVAL;
 300
 301                 default:
 302                         assert_not_reached("Unhandled option");
 303                 }
 304
 305         if (arg_cat_config && argc > optind)
 306                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 307                                        "Positional arguments are not allowed with --cat-config");
 308
 309         return 1;
 310 }
 311
 312 static int run(int argc, char *argv[]) {
 313         _cleanup_(ordered_hashmap_freep) OrderedHashmap *sysctl_options = NULL;
 314         int r, k;
 315
 316         r = parse_argv(argc, argv);
 317         if (r <= 0)
 318                 return r;
 319
 320         log_setup_service();
 321
 322         umask(0022);
 323
 324         sysctl_options = ordered_hashmap_new(&option_hash_ops);
 325         if (!sysctl_options)
 326                 return log_oom();
 327
 328         if (argc > optind) {
 329                 int i;
 330
 331                 r = 0;
 332
 333                 for (i = optind; i < argc; i++) {
 334                         k = parse_file(sysctl_options, argv[i], false);
 335                         if (k < 0 && r == 0)
 336                                 r = k;
 337                 }
 338         } else {
 339                 _cleanup_strv_free_ char **files = NULL;
 340                 char **f;
 341
 342                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 343                 if (r < 0)
 344                         return log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 345
 346                 if (arg_cat_config) {
 347                         (void) pager_open(arg_pager_flags);
 348
 349                         return cat_files(NULL, files, 0);
 350                 }
 351
 352                 STRV_FOREACH(f, files) {
 353                         k = parse_file(sysctl_options, *f, true);
 354                         if (k < 0 && r == 0)
 355                                 r = k;
 356                 }
 357         }
 358
 359         k = apply_all(sysctl_options);
 360         if (k < 0 && r == 0)
 361                 r = k;
 362
 363         return r;
 364 }
 365
 366 DEFINE_MAIN_FUNCTION(run);