src/sysctl/sysctl.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <getopt.h>
  22 #include <limits.h>
  23 #include <stdbool.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 #include "conf-files.h"
  29 #include "def.h"
  30 #include "fd-util.h"
  31 #include "fileio.h"
  32 #include "hashmap.h"
  33 #include "log.h"
  34 #include "path-util.h"
  35 #include "string-util.h"
  36 #include "strv.h"
  37 #include "sysctl-util.h"
  38 #include "util.h"
  39
  40 static char **arg_prefixes = NULL;
  41
  42 static const char conf_file_dirs[] = CONF_PATHS_NULSTR("sysctl.d");
  43
  44 static int apply_all(OrderedHashmap *sysctl_options) {
  45         char *property, *value;
  46         Iterator i;
  47         int r = 0;
  48
  49         ORDERED_HASHMAP_FOREACH_KEY(value, property, sysctl_options, i) {
  50                 int k;
  51
  52                 k = sysctl_write(property, value);
  53                 if (k < 0) {
  54                         /* If the sysctl is not available in the kernel or we are running with reduced privileges and
  55                          * cannot write it, then log about the issue at LOG_NOTICE level, and proceed without
  56                          * failing. (EROFS is treated as a permission problem here, since that's how container managers
  57                          * usually protected their sysctls.) In all other cases log an error and make the tool fail. */
  58
  59                         if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT))
  60                                 log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", value, property);
  61                         else {
  62                                 log_error_errno(k, "Couldn't write '%s' to '%s': %m", value, property);
  63                                 if (r == 0)
  64                                         r = k;
  65                         }
  66                 }
  67         }
  68
  69         return r;
  70 }
  71
  72 static bool test_prefix(const char *p) {
  73         char **i;
  74
  75         if (strv_isempty(arg_prefixes))
  76                 return true;
  77
  78         STRV_FOREACH(i, arg_prefixes) {
  79                 const char *t;
  80
  81                 t = path_startswith(*i, "/proc/sys/");
  82                 if (!t)
  83                         t = *i;
  84                 if (path_startswith(p, t))
  85                         return true;
  86         }
  87
  88         return false;
  89 }
  90
  91 static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ignore_enoent) {
  92         _cleanup_fclose_ FILE *f = NULL;
  93         unsigned c = 0;
  94         int r;
  95
  96         assert(path);
  97
  98         r = search_and_fopen_nulstr(path, "re", NULL, conf_file_dirs, &f);
  99         if (r < 0) {
 100                 if (ignore_enoent && r == -ENOENT)
 101                         return 0;
 102
 103                 return log_error_errno(r, "Failed to open file '%s', ignoring: %m", path);
 104         }
 105
 106         log_debug("Parsing %s", path);
 107         for (;;) {
 108                 char l[LINE_MAX], *p, *value, *new_value, *property, *existing;
 109                 void *v;
 110                 int k;
 111
 112                 if (!fgets(l, sizeof(l), f)) {
 113                         if (feof(f))
 114                                 break;
 115
 116                         return log_error_errno(errno, "Failed to read file '%s', ignoring: %m", path);
 117                 }
 118
 119                 c++;
 120
 121                 p = strstrip(l);
 122                 if (!*p)
 123                         continue;
 124
 125                 if (strchr(COMMENTS "\n", *p))
 126                         continue;
 127
 128                 value = strchr(p, '=');
 129                 if (!value) {
 130                         log_error("Line is not an assignment at '%s:%u': %s", path, c, value);
 131
 132                         if (r == 0)
 133                                 r = -EINVAL;
 134                         continue;
 135                 }
 136
 137                 *value = 0;
 138                 value++;
 139
 140                 p = sysctl_normalize(strstrip(p));
 141                 value = strstrip(value);
 142
 143                 if (!test_prefix(p))
 144                         continue;
 145
 146                 existing = ordered_hashmap_get2(sysctl_options, p, &v);
 147                 if (existing) {
 148                         if (streq(value, existing))
 149                                 continue;
 150
 151                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
 152                         free(ordered_hashmap_remove(sysctl_options, p));
 153                         free(v);
 154                 }
 155
 156                 property = strdup(p);
 157                 if (!property)
 158                         return log_oom();
 159
 160                 new_value = strdup(value);
 161                 if (!new_value) {
 162                         free(property);
 163                         return log_oom();
 164                 }
 165
 166                 k = ordered_hashmap_put(sysctl_options, property, new_value);
 167                 if (k < 0) {
 168                         log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", property);
 169                         free(property);
 170                         free(new_value);
 171                         return k;
 172                 }
 173         }
 174
 175         return r;
 176 }
 177
 178 static void help(void) {
 179         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 180                "Applies kernel sysctl settings.\n\n"
 181                "  -h --help             Show this help\n"
 182                "     --version          Show package version\n"
 183                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 184                , program_invocation_short_name);
 185 }
 186
 187 static int parse_argv(int argc, char *argv[]) {
 188
 189         enum {
 190                 ARG_VERSION = 0x100,
 191                 ARG_PREFIX
 192         };
 193
 194         static const struct option options[] = {
 195                 { "help",      no_argument,       NULL, 'h'           },
 196                 { "version",   no_argument,       NULL, ARG_VERSION   },
 197                 { "prefix",    required_argument, NULL, ARG_PREFIX    },
 198                 {}
 199         };
 200
 201         int c;
 202
 203         assert(argc >= 0);
 204         assert(argv);
 205
 206         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 207
 208                 switch (c) {
 209
 210                 case 'h':
 211                         help();
 212                         return 0;
 213
 214                 case ARG_VERSION:
 215                         return version();
 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 '?':
 240                         return -EINVAL;
 241
 242                 default:
 243                         assert_not_reached("Unhandled option");
 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(&string_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_nulstr(&files, ".conf", NULL, 0, conf_file_dirs);
 284                 if (r < 0) {
 285                         log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 286                         goto finish;
 287                 }
 288
 289                 STRV_FOREACH(f, files) {
 290                         k = parse_file(sysctl_options, *f, true);
 291                         if (k < 0 && r == 0)
 292                                 r = k;
 293                 }
 294         }
 295
 296         k = apply_all(sysctl_options);
 297         if (k < 0 && r == 0)
 298                 r = k;
 299
 300 finish:
 301         ordered_hashmap_free_free_free(sysctl_options);
 302         strv_free(arg_prefixes);
 303
 304         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 305 }