src/sysctl/sysctl.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <getopt.h>
  10 #include <limits.h>
  11 #include <stdbool.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15
  16 #include "conf-files.h"
  17 #include "def.h"
  18 #include "fd-util.h"
  19 #include "fileio.h"
  20 #include "hashmap.h"
  21 #include "log.h"
  22 #include "path-util.h"
  23 #include "string-util.h"
  24 #include "strv.h"
  25 #include "sysctl-util.h"
  26 #include "terminal-util.h"
  27 #include "util.h"
  28
  29 static char **arg_prefixes = NULL;
  30 static bool arg_cat_config = false;
  31
  32 static int apply_all(OrderedHashmap *sysctl_options) {
  33         char *property, *value;
  34         Iterator i;
  35         int r = 0;
  36
  37         ORDERED_HASHMAP_FOREACH_KEY(value, property, sysctl_options, i) {
  38                 int k;
  39
  40                 k = sysctl_write(property, value);
  41                 if (k < 0) {
  42                         /* If the sysctl is not available in the kernel or we are running with reduced privileges and
  43                          * cannot write it, then log about the issue at LOG_NOTICE level, and proceed without
  44                          * failing. (EROFS is treated as a permission problem here, since that's how container managers
  45                          * usually protected their sysctls.) In all other cases log an error and make the tool fail. */
  46
  47                         if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT))
  48                                 log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", value, property);
  49                         else {
  50                                 log_error_errno(k, "Couldn't write '%s' to '%s': %m", value, property);
  51                                 if (r == 0)
  52                                         r = k;
  53                         }
  54                 }
  55         }
  56
  57         return r;
  58 }
  59
  60 static bool test_prefix(const char *p) {
  61         char **i;
  62
  63         if (strv_isempty(arg_prefixes))
  64                 return true;
  65
  66         STRV_FOREACH(i, arg_prefixes) {
  67                 const char *t;
  68
  69                 t = path_startswith(*i, "/proc/sys/");
  70                 if (!t)
  71                         t = *i;
  72                 if (path_startswith(p, t))
  73                         return true;
  74         }
  75
  76         return false;
  77 }
  78
  79 static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ignore_enoent) {
  80         _cleanup_fclose_ FILE *f = NULL;
  81         unsigned c = 0;
  82         int r;
  83
  84         assert(path);
  85
  86         r = search_and_fopen(path, "re", NULL, (const char**) CONF_PATHS_STRV("sysctl.d"), &f);
  87         if (r < 0) {
  88                 if (ignore_enoent && r == -ENOENT)
  89                         return 0;
  90
  91                 return log_error_errno(r, "Failed to open file '%s', ignoring: %m", path);
  92         }
  93
  94         log_debug("Parsing %s", path);
  95         for (;;) {
  96                 char *p, *value, *new_value, *property, *existing;
  97                 _cleanup_free_ char *l = NULL;
  98                 void *v;
  99                 int k;
 100
 101                 k = read_line(f, LONG_LINE_MAX, &l);
 102                 if (k == 0)
 103                         break;
 104                 if (k < 0)
 105                         return log_error_errno(k, "Failed to read file '%s', ignoring: %m", path);
 106
 107                 c++;
 108
 109                 p = strstrip(l);
 110
 111                 if (isempty(p))
 112                         continue;
 113                 if (strchr(COMMENTS "\n", *p))
 114                         continue;
 115
 116                 value = strchr(p, '=');
 117                 if (!value) {
 118                         log_error("Line is not an assignment at '%s:%u': %s", path, c, value);
 119
 120                         if (r == 0)
 121                                 r = -EINVAL;
 122                         continue;
 123                 }
 124
 125                 *value = 0;
 126                 value++;
 127
 128                 p = sysctl_normalize(strstrip(p));
 129                 value = strstrip(value);
 130
 131                 if (!test_prefix(p))
 132                         continue;
 133
 134                 existing = ordered_hashmap_get2(sysctl_options, p, &v);
 135                 if (existing) {
 136                         if (streq(value, existing))
 137                                 continue;
 138
 139                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
 140                         free(ordered_hashmap_remove(sysctl_options, p));
 141                         free(v);
 142                 }
 143
 144                 property = strdup(p);
 145                 if (!property)
 146                         return log_oom();
 147
 148                 new_value = strdup(value);
 149                 if (!new_value) {
 150                         free(property);
 151                         return log_oom();
 152                 }
 153
 154                 k = ordered_hashmap_put(sysctl_options, property, new_value);
 155                 if (k < 0) {
 156                         log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", property);
 157                         free(property);
 158                         free(new_value);
 159                         return k;
 160                 }
 161         }
 162
 163         return r;
 164 }
 165
 166 static void help(void) {
 167         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 168                "Applies kernel sysctl settings.\n\n"
 169                "  -h --help             Show this help\n"
 170                "     --version          Show package version\n"
 171                "     --cat-config       Show configuration files\n"
 172                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 173                , program_invocation_short_name);
 174 }
 175
 176 static int parse_argv(int argc, char *argv[]) {
 177
 178         enum {
 179                 ARG_VERSION = 0x100,
 180                 ARG_CAT_CONFIG,
 181                 ARG_PREFIX,
 182         };
 183
 184         static const struct option options[] = {
 185                 { "help",       no_argument,       NULL, 'h'            },
 186                 { "version",    no_argument,       NULL, ARG_VERSION    },
 187                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 188                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 189                 {}
 190         };
 191
 192         int c;
 193
 194         assert(argc >= 0);
 195         assert(argv);
 196
 197         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 198
 199                 switch (c) {
 200
 201                 case 'h':
 202                         help();
 203                         return 0;
 204
 205                 case ARG_VERSION:
 206                         return version();
 207
 208                 case ARG_CAT_CONFIG:
 209                         arg_cat_config = true;
 210                         break;
 211
 212                 case ARG_PREFIX: {
 213                         char *p;
 214
 215                         /* We used to require people to specify absolute paths
 216                          * in /proc/sys in the past. This is kinda useless, but
 217                          * we need to keep compatibility. We now support any
 218                          * sysctl name available. */
 219                         sysctl_normalize(optarg);
 220
 221                         if (path_startswith(optarg, "/proc/sys"))
 222                                 p = strdup(optarg);
 223                         else
 224                                 p = strappend("/proc/sys/", optarg);
 225                         if (!p)
 226                                 return log_oom();
 227
 228                         if (strv_consume(&arg_prefixes, p) < 0)
 229                                 return log_oom();
 230
 231                         break;
 232                 }
 233
 234                 case '?':
 235                         return -EINVAL;
 236
 237                 default:
 238                         assert_not_reached("Unhandled option");
 239                 }
 240
 241         if (arg_cat_config && argc > optind) {
 242                 log_error("Positional arguments are not allowed with --cat-config");
 243                 return -EINVAL;
 244         }
 245
 246         return 1;
 247 }
 248
 249 int main(int argc, char *argv[]) {
 250         OrderedHashmap *sysctl_options = NULL;
 251         int r = 0, k;
 252
 253         r = parse_argv(argc, argv);
 254         if (r <= 0)
 255                 goto finish;
 256
 257         log_set_target(LOG_TARGET_AUTO);
 258         log_parse_environment();
 259         log_open();
 260
 261         umask(0022);
 262
 263         sysctl_options = ordered_hashmap_new(&path_hash_ops);
 264         if (!sysctl_options) {
 265                 r = log_oom();
 266                 goto finish;
 267         }
 268
 269         r = 0;
 270
 271         if (argc > optind) {
 272                 int i;
 273
 274                 for (i = optind; i < argc; i++) {
 275                         k = parse_file(sysctl_options, argv[i], false);
 276                         if (k < 0 && r == 0)
 277                                 r = k;
 278                 }
 279         } else {
 280                 _cleanup_strv_free_ char **files = NULL;
 281                 char **f;
 282
 283                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 284                 if (r < 0) {
 285                         log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 286                         goto finish;
 287                 }
 288
 289                 if (arg_cat_config) {
 290                         r = cat_files(NULL, files, 0);
 291                         goto finish;
 292                 }
 293
 294                 STRV_FOREACH(f, files) {
 295                         k = parse_file(sysctl_options, *f, true);
 296                         if (k < 0 && r == 0)
 297                                 r = k;
 298                 }
 299         }
 300
 301         k = apply_all(sysctl_options);
 302         if (k < 0 && r == 0)
 303                 r = k;
 304
 305 finish:
 306         ordered_hashmap_free_free_free(sysctl_options);
 307         strv_free(arg_prefixes);
 308
 309         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 310 }