src/binfmt/binfmt.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   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 <sys/stat.h>
  10 #include <sys/types.h>
  11
  12 #include "alloc-util.h"
  13 #include "binfmt-util.h"
  14 #include "build.h"
  15 #include "conf-files.h"
  16 #include "constants.h"
  17 #include "fd-util.h"
  18 #include "fileio.h"
  19 #include "log.h"
  20 #include "main-func.h"
  21 #include "pager.h"
  22 #include "path-util.h"
  23 #include "pretty-print.h"
  24 #include "string-util.h"
  25 #include "strv.h"
  26
  27 static bool arg_cat_config = false;
  28 static PagerFlags arg_pager_flags = 0;
  29 static bool arg_unregister = false;
  30
  31 static int delete_rule(const char *rulename) {
  32         const char *fn = strjoina("/proc/sys/fs/binfmt_misc/", rulename);
  33         return write_string_file(fn, "-1", WRITE_STRING_FILE_DISABLE_BUFFER);
  34 }
  35
  36 static int apply_rule(const char *filename, unsigned line, const char *rule) {
  37         assert(filename);
  38         assert(line > 0);
  39         assert(rule);
  40         assert(rule[0]);
  41
  42         _cleanup_free_ char *rulename = NULL;
  43         const char *e;
  44         int r;
  45
  46         e = strchrnul(rule + 1, rule[0]);
  47         rulename = strndup(rule + 1, e - rule - 1);
  48         if (!rulename)
  49                 return log_oom();
  50
  51         if (!filename_is_valid(rulename) ||
  52             STR_IN_SET(rulename, "register", "status"))
  53                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
  54                                        "%s:%u: Rule name '%s' is not valid, refusing.",
  55                                        filename, line, rulename);
  56         r = delete_rule(rulename);
  57         if (r < 0 && r != -ENOENT)
  58                 log_warning_errno(r, "%s:%u: Failed to delete rule '%s', ignoring: %m",
  59                                   filename, line, rulename);
  60         if (r >= 0)
  61                 log_debug("%s:%u: Rule '%s' deleted.", filename, line, rulename);
  62
  63         r = write_string_file("/proc/sys/fs/binfmt_misc/register", rule, WRITE_STRING_FILE_DISABLE_BUFFER);
  64         if (r < 0)
  65                 return log_error_errno(r, "%s:%u: Failed to add binary format '%s': %m",
  66                                        filename, line, rulename);
  67
  68         log_debug("%s:%u: Binary format '%s' registered.", filename, line, rulename);
  69         return 0;
  70 }
  71
  72 static int apply_file(const char *filename, bool ignore_enoent) {
  73         _cleanup_fclose_ FILE *f = NULL;
  74         _cleanup_free_ char *pp = NULL;
  75         int r;
  76
  77         assert(filename);
  78
  79         r = search_and_fopen(filename, "re", NULL, (const char**) CONF_PATHS_STRV("binfmt.d"), &f, &pp);
  80         if (r < 0) {
  81                 if (ignore_enoent && r == -ENOENT)
  82                         return 0;
  83
  84                 return log_error_errno(r, "Failed to open file '%s': %m", filename);
  85         }
  86
  87         log_debug("Applying %s%s", pp, special_glyph(SPECIAL_GLYPH_ELLIPSIS));
  88         for (unsigned line = 1;; line++) {
  89                 _cleanup_free_ char *text = NULL;
  90                 char *p;
  91                 int k;
  92
  93                 k = read_line(f, LONG_LINE_MAX, &text);
  94                 if (k < 0)
  95                         return log_error_errno(k, "Failed to read file '%s': %m", pp);
  96                 if (k == 0)
  97                         break;
  98
  99                 p = strstrip(text);
 100                 if (isempty(p))
 101                         continue;
 102                 if (strchr(COMMENTS, p[0]))
 103                         continue;
 104
 105                 k = apply_rule(filename, line, p);
 106                 if (k < 0 && r >= 0)
 107                         r = k;
 108         }
 109
 110         return r;
 111 }
 112
 113 static int help(void) {
 114         _cleanup_free_ char *link = NULL;
 115         int r;
 116
 117         r = terminal_urlify_man("systemd-binfmt.service", "8", &link);
 118         if (r < 0)
 119                 return log_oom();
 120
 121         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 122                "Registers binary formats with the kernel.\n\n"
 123                "  -h --help             Show this help\n"
 124                "     --version          Show package version\n"
 125                "     --cat-config       Show configuration files\n"
 126                "     --no-pager         Do not pipe output into a pager\n"
 127                "     --unregister       Unregister all existing entries\n"
 128                "\nSee the %s for details.\n",
 129                program_invocation_short_name,
 130                link);
 131
 132         return 0;
 133 }
 134
 135 static int parse_argv(int argc, char *argv[]) {
 136         enum {
 137                 ARG_VERSION = 0x100,
 138                 ARG_CAT_CONFIG,
 139                 ARG_NO_PAGER,
 140                 ARG_UNREGISTER,
 141         };
 142
 143         static const struct option options[] = {
 144                 { "help",       no_argument, NULL, 'h'            },
 145                 { "version",    no_argument, NULL, ARG_VERSION    },
 146                 { "cat-config", no_argument, NULL, ARG_CAT_CONFIG },
 147                 { "no-pager",   no_argument, NULL, ARG_NO_PAGER   },
 148                 { "unregister", no_argument, NULL, ARG_UNREGISTER },
 149                 {}
 150         };
 151
 152         int c;
 153
 154         assert(argc >= 0);
 155         assert(argv);
 156
 157         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 158
 159                 switch (c) {
 160
 161                 case 'h':
 162                         return help();
 163
 164                 case ARG_VERSION:
 165                         return version();
 166
 167                 case ARG_CAT_CONFIG:
 168                         arg_cat_config = true;
 169                         break;
 170
 171                 case ARG_NO_PAGER:
 172                         arg_pager_flags |= PAGER_DISABLE;
 173                         break;
 174
 175                 case ARG_UNREGISTER:
 176                         arg_unregister = true;
 177                         break;
 178
 179                 case '?':
 180                         return -EINVAL;
 181
 182                 default:
 183                         assert_not_reached();
 184                 }
 185
 186         if ((arg_unregister || arg_cat_config) && argc > optind)
 187                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 188                                        "Positional arguments are not allowed with --cat-config or --unregister");
 189
 190         return 1;
 191 }
 192
 193 static int run(int argc, char *argv[]) {
 194         int r, k;
 195
 196         r = parse_argv(argc, argv);
 197         if (r <= 0)
 198                 return r;
 199
 200         log_setup();
 201
 202         umask(0022);
 203
 204         r = 0;
 205
 206         if (arg_unregister)
 207                 return disable_binfmt();
 208
 209         if (argc > optind)
 210                 for (int i = optind; i < argc; i++) {
 211                         k = apply_file(argv[i], false);
 212                         if (k < 0 && r >= 0)
 213                                 r = k;
 214                 }
 215         else {
 216                 _cleanup_strv_free_ char **files = NULL;
 217
 218                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("binfmt.d"));
 219                 if (r < 0)
 220                         return log_error_errno(r, "Failed to enumerate binfmt.d files: %m");
 221
 222                 if (arg_cat_config) {
 223                         pager_open(arg_pager_flags);
 224
 225                         return cat_files(NULL, files, 0);
 226                 }
 227
 228                 /* Flush out all rules */
 229                 r = write_string_file("/proc/sys/fs/binfmt_misc/status", "-1", WRITE_STRING_FILE_DISABLE_BUFFER);
 230                 if (r < 0)
 231                         log_warning_errno(r, "Failed to flush binfmt_misc rules, ignoring: %m");
 232                 else
 233                         log_debug("Flushed all binfmt_misc rules.");
 234
 235                 STRV_FOREACH(f, files) {
 236                         k = apply_file(*f, true);
 237                         if (k < 0 && r >= 0)
 238                                 r = k;
 239                 }
 240         }
 241
 242         return r;
 243 }
 244
 245 DEFINE_MAIN_FUNCTION(run);