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