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
  11 #include "conf-files.h"
  12 #include "def.h"
  13 #include "fd-util.h"
  14 #include "fileio.h"
  15 #include "hashmap.h"
  16 #include "log.h"
  17 #include "main-func.h"
  18 #include "pager.h"
  19 #include "path-util.h"
  20 #include "pretty-print.h"
  21 #include "string-util.h"
  22 #include "strv.h"
  23 #include "sysctl-util.h"
  24 #include "util.h"
  25
  26 static char **arg_prefixes = NULL;
  27 static bool arg_cat_config = false;
  28 static PagerFlags arg_pager_flags = 0;
  29
  30 STATIC_DESTRUCTOR_REGISTER(arg_prefixes, strv_freep);
  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, p);
 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 int help(void) {
 167         _cleanup_free_ char *link = NULL;
 168         int r;
 169
 170         r = terminal_urlify_man("systemd-sysctl.service", "8", &link);
 171         if (r < 0)
 172                 return log_oom();
 173
 174         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 175                "Applies kernel sysctl settings.\n\n"
 176                "  -h --help             Show this help\n"
 177                "     --version          Show package version\n"
 178                "     --cat-config       Show configuration files\n"
 179                "     --prefix=PATH      Only apply rules with the specified prefix\n"
 180                "     --no-pager         Do not pipe output into a pager\n"
 181                "\nSee the %s for details.\n"
 182                , program_invocation_short_name
 183                , link
 184         );
 185
 186         return 0;
 187 }
 188
 189 static int parse_argv(int argc, char *argv[]) {
 190
 191         enum {
 192                 ARG_VERSION = 0x100,
 193                 ARG_CAT_CONFIG,
 194                 ARG_PREFIX,
 195                 ARG_NO_PAGER,
 196         };
 197
 198         static const struct option options[] = {
 199                 { "help",       no_argument,       NULL, 'h'            },
 200                 { "version",    no_argument,       NULL, ARG_VERSION    },
 201                 { "cat-config", no_argument,       NULL, ARG_CAT_CONFIG },
 202                 { "prefix",     required_argument, NULL, ARG_PREFIX     },
 203                 { "no-pager",   no_argument,       NULL, ARG_NO_PAGER   },
 204                 {}
 205         };
 206
 207         int c;
 208
 209         assert(argc >= 0);
 210         assert(argv);
 211
 212         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 213
 214                 switch (c) {
 215
 216                 case 'h':
 217                         return help();
 218
 219                 case ARG_VERSION:
 220                         return version();
 221
 222                 case ARG_CAT_CONFIG:
 223                         arg_cat_config = true;
 224                         break;
 225
 226                 case ARG_PREFIX: {
 227                         char *p;
 228
 229                         /* We used to require people to specify absolute paths
 230                          * in /proc/sys in the past. This is kinda useless, but
 231                          * we need to keep compatibility. We now support any
 232                          * sysctl name available. */
 233                         sysctl_normalize(optarg);
 234
 235                         if (path_startswith(optarg, "/proc/sys"))
 236                                 p = strdup(optarg);
 237                         else
 238                                 p = strappend("/proc/sys/", optarg);
 239                         if (!p)
 240                                 return log_oom();
 241
 242                         if (strv_consume(&arg_prefixes, p) < 0)
 243                                 return log_oom();
 244
 245                         break;
 246                 }
 247
 248                 case ARG_NO_PAGER:
 249                         arg_pager_flags |= PAGER_DISABLE;
 250                         break;
 251
 252                 case '?':
 253                         return -EINVAL;
 254
 255                 default:
 256                         assert_not_reached("Unhandled option");
 257                 }
 258
 259         if (arg_cat_config && argc > optind)
 260                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 261                                        "Positional arguments are not allowed with --cat-config");
 262
 263         return 1;
 264 }
 265
 266 static int run(int argc, char *argv[]) {
 267         _cleanup_(ordered_hashmap_free_free_freep) OrderedHashmap *sysctl_options = NULL;
 268         int r, k;
 269
 270         r = parse_argv(argc, argv);
 271         if (r <= 0)
 272                 return r;
 273
 274         log_setup_service();
 275
 276         umask(0022);
 277
 278         sysctl_options = ordered_hashmap_new(&path_hash_ops);
 279         if (!sysctl_options)
 280                 return log_oom();
 281
 282         r = 0;
 283
 284         if (argc > optind) {
 285                 int i;
 286
 287                 for (i = optind; i < argc; i++) {
 288                         k = parse_file(sysctl_options, argv[i], false);
 289                         if (k < 0 && r == 0)
 290                                 r = k;
 291                 }
 292         } else {
 293                 _cleanup_strv_free_ char **files = NULL;
 294                 char **f;
 295
 296                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("sysctl.d"));
 297                 if (r < 0)
 298                         return log_error_errno(r, "Failed to enumerate sysctl.d files: %m");
 299
 300                 if (arg_cat_config) {
 301                         (void) pager_open(arg_pager_flags);
 302
 303                         return cat_files(NULL, files, 0);
 304                 }
 305
 306                 STRV_FOREACH(f, files) {
 307                         k = parse_file(sysctl_options, *f, true);
 308                         if (k < 0 && r == 0)
 309                                 r = k;
 310                 }
 311         }
 312
 313         k = apply_all(sysctl_options);
 314         if (k < 0 && r == 0)
 315                 r = k;
 316
 317         return r;
 318 }
 319
 320 DEFINE_MAIN_FUNCTION(run);