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
  11 #include "conf-files.h"
  12 #include "def.h"
  13 #include "fd-util.h"
  14 #include "fileio.h"
  15 #include "hashmap.h"
  16 #include "log.h"
  17 #include "pager.h"
  18 #include "path-util.h"
  19 #include "string-util.h"
  20 #include "strv.h"
  21 #include "sysctl-util.h"
  22 #include "terminal-util.h"
  23 #include "util.h"
  24
  25 static char **arg_prefixes = NULL;
  26 static bool arg_cat_config = false;
  27 static PagerFlags arg_pager_flags = 0;
  28
  29 static int apply_all(OrderedHashmap *sysctl_options) {
  30         char *property, *value;
  31         Iterator i;
  32         int r = 0;
  33
  34         ORDERED_HASHMAP_FOREACH_KEY(value, property, sysctl_options, i) {
  35                 int k;
  36
  37                 k = sysctl_write(property, value);
  38                 if (k < 0) {
  39                         /* If the sysctl is not available in the kernel or we are running with reduced privileges and
  40                          * cannot write it, then log about the issue at LOG_NOTICE level, and proceed without
  41                          * failing. (EROFS is treated as a permission problem here, since that's how container managers
  42                          * usually protected their sysctls.) In all other cases log an error and make the tool fail. */
  43
  44                         if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT))
  45                                 log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", value, property);
  46                         else {
  47                                 log_error_errno(k, "Couldn't write '%s' to '%s': %m", value, property);
  48                                 if (r == 0)
  49                                         r = k;
  50                         }
  51                 }
  52         }
  53
  54         return r;
  55 }
  56
  57 static bool test_prefix(const char *p) {
  58         char **i;
  59
  60         if (strv_isempty(arg_prefixes))
  61                 return true;
  62
  63         STRV_FOREACH(i, arg_prefixes) {
  64                 const char *t;
  65
  66                 t = path_startswith(*i, "/proc/sys/");
  67                 if (!t)
  68                         t = *i;
  69                 if (path_startswith(p, t))
  70                         return true;
  71         }
  72
  73         return false;
  74 }
  75
  76 static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ignore_enoent) {
  77         _cleanup_fclose_ FILE *f = NULL;
  78         unsigned c = 0;
  79         int r;
  80
  81         assert(path);
  82
  83         r = search_and_fopen(path, "re", NULL, (const char**) CONF_PATHS_STRV("sysctl.d"), &f);
  84         if (r < 0) {
  85                 if (ignore_enoent && r == -ENOENT)
  86                         return 0;
  87
  88                 return log_error_errno(r, "Failed to open file '%s', ignoring: %m", path);
  89         }
  90
  91         log_debug("Parsing %s", path);
  92         for (;;) {
  93                 char *p, *value, *new_value, *property, *existing;
  94                 _cleanup_free_ char *l = NULL;
  95                 void *v;
  96                 int k;
  97
  98                 k = read_line(f, LONG_LINE_MAX, &l);
  99                 if (k == 0)
 100                         break;
 101                 if (k < 0)
 102                         return log_error_errno(k, "Failed to read file '%s', ignoring: %m", path);
 103
 104                 c++;
 105
 106                 p = strstrip(l);
 107
 108                 if (isempty(p))
 109                         continue;
 110                 if (strchr(COMMENTS "\n", *p))
 111                         continue;
 112
 113                 value = strchr(p, '=');
 114                 if (!value) {
 115                         log_error("Line is not an assignment at '%s:%u': %s", path, c, value);
 116
 117                         if (r == 0)
 118                                 r = -EINVAL;
 119                         continue;
 120                 }
 121
 122                 *value = 0;
 123                 value++;
 124
 125                 p = sysctl_normalize(strstrip(p));
 126                 value = strstrip(value);
 127
 128                 if (!test_prefix(p))
 129                         continue;
 130
 131                 existing = ordered_hashmap_get2(sysctl_options, p, &v);
 132                 if (existing) {
 133                         if (streq(value, existing))
 134                                 continue;
 135
 136                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
 137                         free(ordered_hashmap_remove(sysctl_options, p));
 138                         free(v);
 139                 }
 140
 141                 property = strdup(p);
 142                 if (!property)
 143                         return log_oom();
 144
 145                 new_value = strdup(value);
 146                 if (!new_value) {
 147                         free(property);
 148                         return log_oom();
 149                 }
 150
 151                 k = ordered_hashmap_put(sysctl_options, property, new_value);
 152                 if (k < 0) {
 153                         log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", property);
 154                         free(property);
 155                         free(new_value);
 156                         return k;
 157                 }
 158         }
 159
 160         return r;
 161 }
 162
 163 static int help(void) {
 164         _cleanup_free_ char *link = NULL;
 165         int r;
 166
 167         r = terminal_urlify_man("systemd-sysctl.service", "8", &link);
 168         if (r < 0)
 169                 return log_oom();
 170
 171         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 172                "Applies kernel sysctl settings.\n\n"
 173                "  -h --help             Show this help\n"
 174                "     --version          Show package version\n"
 175                "     --cat-config       Show configuration files\n"
 176                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 177                "     --no-pager         Do not pipe output into a pager\n"
 178                "\nSee the %s for details.\n"
 179                , program_invocation_short_name
 180                , link
 181         );
 182
 183         return 0;
 184 }
 185
 186 static int parse_argv(int argc, char *argv[]) {
 187
 188         enum {
 189                 ARG_VERSION = 0x100,
 190                 ARG_CAT_CONFIG,
 191                 ARG_PREFIX,
 192                 ARG_NO_PAGER,
 193         };
 194
 195         static const struct option options[] = {
 196                 { "help",       no_argument,       NULL, 'h'            },
 197                 { "version",    no_argument,       NULL, ARG_VERSION    },
 198                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 199                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 200                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
 201                 {}
 202         };
 203
 204         int c;
 205
 206         assert(argc >= 0);
 207         assert(argv);
 208
 209         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 210
 211                 switch (c) {
 212
 213                 case 'h':
 214                         return help();
 215
 216                 case ARG_VERSION:
 217                         return version();
 218
 219                 case ARG_CAT_CONFIG:
 220                         arg_cat_config = true;
 221                         break;
 222
 223                 case ARG_PREFIX: {
 224                         char *p;
 225
 226                         /* We used to require people to specify absolute paths
 227                          * in /proc/sys in the past. This is kinda useless, but
 228                          * we need to keep compatibility. We now support any
 229                          * sysctl name available. */
 230                         sysctl_normalize(optarg);
 231
 232                         if (path_startswith(optarg, "/proc/sys"))
 233                                 p = strdup(optarg);
 234                         else
 235                                 p = strappend("/proc/sys/", optarg);
 236                         if (!p)
 237                                 return log_oom();
 238
 239                         if (strv_consume(&arg_prefixes, p) < 0)
 240                                 return log_oom();
 241
 242                         break;
 243                 }
 244
 245                 case ARG_NO_PAGER:
 246                         arg_pager_flags |= PAGER_DISABLE;
 247                         break;
 248
 249                 case '?':
 250                         return -EINVAL;
 251
 252                 default:
 253                         assert_not_reached("Unhandled option");
 254                 }
 255
 256         if (arg_cat_config && argc > optind) {
 257                 log_error("Positional arguments are not allowed with --cat-config");
 258                 return -EINVAL;
 259         }
 260
 261         return 1;
 262 }
 263
 264 int main(int argc, char *argv[]) {
 265         OrderedHashmap *sysctl_options = NULL;
 266         int r = 0, k;
 267
 268         r = parse_argv(argc, argv);
 269         if (r <= 0)
 270                 goto finish;
 271
 272         log_setup_service();
 273
 274         umask(0022);
 275
 276         sysctl_options = ordered_hashmap_new(&path_hash_ops);
 277         if (!sysctl_options) {
 278                 r = log_oom();
 279                 goto finish;
 280         }
 281
 282         r = 0;
 283
 284         if (argc > optind) {
 285                 int i;
 286
 287                 for (i = optind; i < argc; i++) {
 288                         k = parse_file(sysctl_options, argv[i], false);
 289                         if (k < 0 && r == 0)
 290                                 r = k;
 291                 }
 292         } else {
 293                 _cleanup_strv_free_ char **files = NULL;
 294                 char **f;
 295
 296                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 297                 if (r < 0) {
 298                         log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 299                         goto finish;
 300                 }
 301
 302                 if (arg_cat_config) {
 303                         (void) pager_open(arg_pager_flags);
 304
 305                         r = cat_files(NULL, files, 0);
 306                         goto finish;
 307                 }
 308
 309                 STRV_FOREACH(f, files) {
 310                         k = parse_file(sysctl_options, *f, true);
 311                         if (k < 0 && r == 0)
 312                                 r = k;
 313                 }
 314         }
 315
 316         k = apply_all(sysctl_options);
 317         if (k < 0 && r == 0)
 318                 r = k;
 319
 320 finish:
 321         pager_close();
 322
 323         ordered_hashmap_free_free_free(sysctl_options);
 324         strv_free(arg_prefixes);
 325
 326         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 327 }