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