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