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         int r;
  44
  45         rulename = strdupcspn(rule + 1, CHAR_TO_STR(rule[0]));
  46         if (!rulename)
  47                 return log_oom();
  48
  49         if (!filename_is_valid(rulename) ||
  50             STR_IN_SET(rulename, "register", "status"))
  51                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
  52                                        "%s:%u: Rule name '%s' is not valid, refusing.",
  53                                        filename, line, rulename);
  54         r = delete_rule(rulename);
  55         if (r < 0 && r != -ENOENT)
  56                 log_warning_errno(r, "%s:%u: Failed to delete rule '%s', ignoring: %m",
  57                                   filename, line, rulename);
  58         if (r >= 0)
  59                 log_debug("%s:%u: Rule '%s' deleted.", filename, line, rulename);
  60
  61         r = write_string_file("/proc/sys/fs/binfmt_misc/register", rule, WRITE_STRING_FILE_DISABLE_BUFFER);
  62         if (r < 0)
  63                 return log_error_errno(r, "%s:%u: Failed to add binary format '%s': %m",
  64                                        filename, line, rulename);
  65
  66         log_debug("%s:%u: Binary format '%s' registered.", filename, line, rulename);
  67         return 0;
  68 }
  69
  70 static int apply_file(const char *filename, bool ignore_enoent) {
  71         _cleanup_fclose_ FILE *f = NULL;
  72         _cleanup_free_ char *pp = NULL;
  73         int r;
  74
  75         assert(filename);
  76
  77         r = search_and_fopen(filename, "re", NULL, (const char**) CONF_PATHS_STRV("binfmt.d"), &f, &pp);
  78         if (r < 0) {
  79                 if (ignore_enoent && r == -ENOENT)
  80                         return 0;
  81
  82                 return log_error_errno(r, "Failed to open file '%s': %m", filename);
  83         }
  84
  85         log_debug("Applying %s%s", pp, special_glyph(SPECIAL_GLYPH_ELLIPSIS));
  86         for (unsigned line = 1;; line++) {
  87                 _cleanup_free_ char *text = NULL;
  88                 char *p;
  89                 int k;
  90
  91                 k = read_line(f, LONG_LINE_MAX, &text);
  92                 if (k < 0)
  93                         return log_error_errno(k, "Failed to read file '%s': %m", pp);
  94                 if (k == 0)
  95                         break;
  96
  97                 p = strstrip(text);
  98                 if (isempty(p))
  99                         continue;
 100                 if (strchr(COMMENTS, p[0]))
 101                         continue;
 102
 103                 RET_GATHER(r, apply_rule(filename, line, p));
 104         }
 105
 106         return r;
 107 }
 108
 109 static int help(void) {
 110         _cleanup_free_ char *link = NULL;
 111         int r;
 112
 113         r = terminal_urlify_man("systemd-binfmt.service", "8", &link);
 114         if (r < 0)
 115                 return log_oom();
 116
 117         printf("%s [OPTIONS...] [CONFIGURATION FILE...]\n\n"
 118                "Registers binary formats with the kernel.\n\n"
 119                "  -h --help             Show this help\n"
 120                "     --version          Show package version\n"
 121                "     --cat-config       Show configuration files\n"
 122                "     --no-pager         Do not pipe output into a pager\n"
 123                "     --unregister       Unregister all existing entries\n"
 124                "\nSee the %s for details.\n",
 125                program_invocation_short_name,
 126                link);
 127
 128         return 0;
 129 }
 130
 131 static int parse_argv(int argc, char *argv[]) {
 132         enum {
 133                 ARG_VERSION = 0x100,
 134                 ARG_CAT_CONFIG,
 135                 ARG_NO_PAGER,
 136                 ARG_UNREGISTER,
 137         };
 138
 139         static const struct option options[] = {
 140                 { "help",       no_argument, NULL, 'h'            },
 141                 { "version",    no_argument, NULL, ARG_VERSION    },
 142                 { "cat-config", no_argument, NULL, ARG_CAT_CONFIG },
 143                 { "no-pager",   no_argument, NULL, ARG_NO_PAGER   },
 144                 { "unregister", no_argument, NULL, ARG_UNREGISTER },
 145                 {}
 146         };
 147
 148         int c;
 149
 150         assert(argc >= 0);
 151         assert(argv);
 152
 153         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 154
 155                 switch (c) {
 156
 157                 case 'h':
 158                         return help();
 159
 160                 case ARG_VERSION:
 161                         return version();
 162
 163                 case ARG_CAT_CONFIG:
 164                         arg_cat_config = true;
 165                         break;
 166
 167                 case ARG_NO_PAGER:
 168                         arg_pager_flags |= PAGER_DISABLE;
 169                         break;
 170
 171                 case ARG_UNREGISTER:
 172                         arg_unregister = true;
 173                         break;
 174
 175                 case '?':
 176                         return -EINVAL;
 177
 178                 default:
 179                         assert_not_reached();
 180                 }
 181
 182         if ((arg_unregister || arg_cat_config) && argc > optind)
 183                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
 184                                        "Positional arguments are not allowed with --cat-config or --unregister");
 185
 186         return 1;
 187 }
 188
 189 static int binfmt_mounted_warn(void) {
 190         int r;
 191
 192         r = binfmt_mounted();
 193         if (r < 0)
 194                 return log_error_errno(r, "Failed to check if /proc/sys/fs/binfmt_misc is mounted: %m");
 195         if (r == 0)
 196                 log_debug("/proc/sys/fs/binfmt_misc is not mounted in read-write mode, skipping.");
 197
 198         return r;
 199 }
 200
 201 static int run(int argc, char *argv[]) {
 202         int r;
 203
 204         r = parse_argv(argc, argv);
 205         if (r <= 0)
 206                 return r;
 207
 208         log_setup();
 209
 210         umask(0022);
 211
 212         r = 0;
 213
 214         if (arg_unregister)
 215                 return disable_binfmt();
 216
 217         if (argc > optind) {
 218                 r = binfmt_mounted_warn();
 219                 if (r <= 0)
 220                         return r;
 221
 222                 for (int i = optind; i < argc; i++)
 223                         RET_GATHER(r, apply_file(argv[i], false));
 224
 225         } else {
 226                 _cleanup_strv_free_ char **files = NULL;
 227
 228                 r = conf_files_list_strv(&files, ".conf", NULL, 0, (const char**) CONF_PATHS_STRV("binfmt.d"));
 229                 if (r < 0)
 230                         return log_error_errno(r, "Failed to enumerate binfmt.d files: %m");
 231
 232                 if (arg_cat_config) {
 233                         pager_open(arg_pager_flags);
 234
 235                         return cat_files(NULL, files, /* flags= */ 0);
 236                 }
 237
 238                 r = binfmt_mounted_warn();
 239                 if (r <= 0)
 240                         return r;
 241
 242                 /* Flush out all rules */
 243                 r = write_string_file("/proc/sys/fs/binfmt_misc/status", "-1", WRITE_STRING_FILE_DISABLE_BUFFER);
 244                 if (r < 0)
 245                         log_warning_errno(r, "Failed to flush binfmt_misc rules, ignoring: %m");
 246                 else
 247                         log_debug("Flushed all binfmt_misc rules.");
 248
 249                 STRV_FOREACH(f, files)
 250                         RET_GATHER(r, apply_file(*f, true));
 251         }
 252
 253         return r;
 254 }
 255
 256 DEFINE_MAIN_FUNCTION(run);