src/sysctl/sysctl.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2010 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <getopt.h>
   8 #include <limits.h>
   9 #include <stdbool.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13
  14 #include "conf-files.h"
  15 #include "def.h"
  16 #include "fd-util.h"
  17 #include "fileio.h"
  18 #include "hashmap.h"
  19 #include "log.h"
  20 #include "pager.h"
  21 #include "path-util.h"
  22 #include "string-util.h"
  23 #include "strv.h"
  24 #include "sysctl-util.h"
  25 #include "terminal-util.h"
  26 #include "util.h"
  27
  28 static char **arg_prefixes = NULL;
  29 static bool arg_cat_config = false;
  30 static bool arg_no_pager = 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                "     --no-pager         Do not pipe output into a pager\n"
 174                , program_invocation_short_name);
 175 }
 176
 177 static int parse_argv(int argc, char *argv[]) {
 178
 179         enum {
 180                 ARG_VERSION = 0x100,
 181                 ARG_CAT_CONFIG,
 182                 ARG_PREFIX,
 183                 ARG_NO_PAGER,
 184         };
 185
 186         static const struct option options[] = {
 187                 { "help",       no_argument,       NULL, 'h'            },
 188                 { "version",    no_argument,       NULL, ARG_VERSION    },
 189                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 190                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 191                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
 192                 {}
 193         };
 194
 195         int c;
 196
 197         assert(argc >= 0);
 198         assert(argv);
 199
 200         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 201
 202                 switch (c) {
 203
 204                 case 'h':
 205                         help();
 206                         return 0;
 207
 208                 case ARG_VERSION:
 209                         return version();
 210
 211                 case ARG_CAT_CONFIG:
 212                         arg_cat_config = true;
 213                         break;
 214
 215                 case ARG_PREFIX: {
 216                         char *p;
 217
 218                         /* We used to require people to specify absolute paths
 219                          * in /proc/sys in the past. This is kinda useless, but
 220                          * we need to keep compatibility. We now support any
 221                          * sysctl name available. */
 222                         sysctl_normalize(optarg);
 223
 224                         if (path_startswith(optarg, "/proc/sys"))
 225                                 p = strdup(optarg);
 226                         else
 227                                 p = strappend("/proc/sys/", optarg);
 228                         if (!p)
 229                                 return log_oom();
 230
 231                         if (strv_consume(&arg_prefixes, p) < 0)
 232                                 return log_oom();
 233
 234                         break;
 235                 }
 236
 237                 case ARG_NO_PAGER:
 238                         arg_no_pager = true;
 239                         break;
 240
 241                 case '?':
 242                         return -EINVAL;
 243
 244                 default:
 245                         assert_not_reached("Unhandled option");
 246                 }
 247
 248         if (arg_cat_config && argc > optind) {
 249                 log_error("Positional arguments are not allowed with --cat-config");
 250                 return -EINVAL;
 251         }
 252
 253         return 1;
 254 }
 255
 256 int main(int argc, char *argv[]) {
 257         OrderedHashmap *sysctl_options = NULL;
 258         int r = 0, k;
 259
 260         r = parse_argv(argc, argv);
 261         if (r <= 0)
 262                 goto finish;
 263
 264         log_set_target(LOG_TARGET_AUTO);
 265         log_parse_environment();
 266         log_open();
 267
 268         umask(0022);
 269
 270         sysctl_options = ordered_hashmap_new(&path_hash_ops);
 271         if (!sysctl_options) {
 272                 r = log_oom();
 273                 goto finish;
 274         }
 275
 276         r = 0;
 277
 278         if (argc > optind) {
 279                 int i;
 280
 281                 for (i = optind; i < argc; i++) {
 282                         k = parse_file(sysctl_options, argv[i], false);
 283                         if (k < 0 && r == 0)
 284                                 r = k;
 285                 }
 286         } else {
 287                 _cleanup_strv_free_ char **files = NULL;
 288                 char **f;
 289
 290                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 291                 if (r < 0) {
 292                         log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 293                         goto finish;
 294                 }
 295
 296                 if (arg_cat_config) {
 297                         (void) pager_open(arg_no_pager, false);
 298
 299                         r = cat_files(NULL, files, 0);
 300                         goto finish;
 301                 }
 302
 303                 STRV_FOREACH(f, files) {
 304                         k = parse_file(sysctl_options, *f, true);
 305                         if (k < 0 && r == 0)
 306                                 r = k;
 307                 }
 308         }
 309
 310         k = apply_all(sysctl_options);
 311         if (k < 0 && r == 0)
 312                 r = k;
 313
 314 finish:
 315         pager_close();
 316
 317         ordered_hashmap_free_free_free(sysctl_options);
 318         strv_free(arg_prefixes);
 319
 320         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 321 }