tools/virtiofsd/helper.c

   1 /*
   2  * FUSE: Filesystem in Userspace
   3  * Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4  *
   5  * Helper functions to create (simple) standalone programs. With the
   6  * aid of these functions it should be possible to create full FUSE
   7  * file system by implementing nothing but the request handlers.
   8
   9  * This program can be distributed under the terms of the GNU LGPLv2.
  10  * See the file COPYING.LIB.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "fuse_i.h"
  15 #include "fuse_lowlevel.h"
  16 #include "fuse_misc.h"
  17 #include "fuse_opt.h"
  18
  19 #include <sys/param.h>
  20 #include <sys/resource.h>
  21
  22 #define FUSE_HELPER_OPT(t, p)                       \
  23     {                                               \
  24         t, offsetof(struct fuse_cmdline_opts, p), 1 \
  25     }
  26 #define FUSE_HELPER_OPT_VALUE(t, p, v)              \
  27     {                                               \
  28         t, offsetof(struct fuse_cmdline_opts, p), v \
  29     }
  30
  31 static const struct fuse_opt fuse_helper_opts[] = {
  32     FUSE_HELPER_OPT("-h", show_help),
  33     FUSE_HELPER_OPT("--help", show_help),
  34     FUSE_HELPER_OPT("-V", show_version),
  35     FUSE_HELPER_OPT("--version", show_version),
  36     FUSE_HELPER_OPT("--print-capabilities", print_capabilities),
  37     FUSE_HELPER_OPT("-d", debug),
  38     FUSE_HELPER_OPT("debug", debug),
  39     FUSE_HELPER_OPT("-d", foreground),
  40     FUSE_HELPER_OPT("debug", foreground),
  41     FUSE_OPT_KEY("-d", FUSE_OPT_KEY_KEEP),
  42     FUSE_OPT_KEY("debug", FUSE_OPT_KEY_KEEP),
  43     FUSE_HELPER_OPT("-f", foreground),
  44     FUSE_HELPER_OPT_VALUE("--daemonize", foreground, 0),
  45     FUSE_HELPER_OPT("fsname=", nodefault_subtype),
  46     FUSE_OPT_KEY("fsname=", FUSE_OPT_KEY_KEEP),
  47     FUSE_HELPER_OPT("subtype=", nodefault_subtype),
  48     FUSE_OPT_KEY("subtype=", FUSE_OPT_KEY_KEEP),
  49     FUSE_HELPER_OPT("max_idle_threads=%u", max_idle_threads),
  50     FUSE_HELPER_OPT("--rlimit-nofile=%lu", rlimit_nofile),
  51     FUSE_HELPER_OPT("--syslog", syslog),
  52     FUSE_HELPER_OPT_VALUE("log_level=debug", log_level, FUSE_LOG_DEBUG),
  53     FUSE_HELPER_OPT_VALUE("log_level=info", log_level, FUSE_LOG_INFO),
  54     FUSE_HELPER_OPT_VALUE("log_level=warn", log_level, FUSE_LOG_WARNING),
  55     FUSE_HELPER_OPT_VALUE("log_level=err", log_level, FUSE_LOG_ERR),
  56     FUSE_OPT_END
  57 };
  58
  59 struct fuse_conn_info_opts {
  60     int atomic_o_trunc;
  61     int no_remote_posix_lock;
  62     int no_remote_flock;
  63     int splice_write;
  64     int splice_move;
  65     int splice_read;
  66     int no_splice_write;
  67     int no_splice_move;
  68     int no_splice_read;
  69     int auto_inval_data;
  70     int no_auto_inval_data;
  71     int no_readdirplus;
  72     int no_readdirplus_auto;
  73     int async_dio;
  74     int no_async_dio;
  75     int writeback_cache;
  76     int no_writeback_cache;
  77     int async_read;
  78     int sync_read;
  79     unsigned max_write;
  80     unsigned max_readahead;
  81     unsigned max_background;
  82     unsigned congestion_threshold;
  83     unsigned time_gran;
  84     int set_max_write;
  85     int set_max_readahead;
  86     int set_max_background;
  87     int set_congestion_threshold;
  88     int set_time_gran;
  89 };
  90
  91 #define CONN_OPTION(t, p, v)                          \
  92     {                                                 \
  93         t, offsetof(struct fuse_conn_info_opts, p), v \
  94     }
  95 static const struct fuse_opt conn_info_opt_spec[] = {
  96     CONN_OPTION("max_write=%u", max_write, 0),
  97     CONN_OPTION("max_write=", set_max_write, 1),
  98     CONN_OPTION("max_readahead=%u", max_readahead, 0),
  99     CONN_OPTION("max_readahead=", set_max_readahead, 1),
 100     CONN_OPTION("max_background=%u", max_background, 0),
 101     CONN_OPTION("max_background=", set_max_background, 1),
 102     CONN_OPTION("congestion_threshold=%u", congestion_threshold, 0),
 103     CONN_OPTION("congestion_threshold=", set_congestion_threshold, 1),
 104     CONN_OPTION("sync_read", sync_read, 1),
 105     CONN_OPTION("async_read", async_read, 1),
 106     CONN_OPTION("atomic_o_trunc", atomic_o_trunc, 1),
 107     CONN_OPTION("no_remote_lock", no_remote_posix_lock, 1),
 108     CONN_OPTION("no_remote_lock", no_remote_flock, 1),
 109     CONN_OPTION("no_remote_flock", no_remote_flock, 1),
 110     CONN_OPTION("no_remote_posix_lock", no_remote_posix_lock, 1),
 111     CONN_OPTION("splice_write", splice_write, 1),
 112     CONN_OPTION("no_splice_write", no_splice_write, 1),
 113     CONN_OPTION("splice_move", splice_move, 1),
 114     CONN_OPTION("no_splice_move", no_splice_move, 1),
 115     CONN_OPTION("splice_read", splice_read, 1),
 116     CONN_OPTION("no_splice_read", no_splice_read, 1),
 117     CONN_OPTION("auto_inval_data", auto_inval_data, 1),
 118     CONN_OPTION("no_auto_inval_data", no_auto_inval_data, 1),
 119     CONN_OPTION("readdirplus=no", no_readdirplus, 1),
 120     CONN_OPTION("readdirplus=yes", no_readdirplus, 0),
 121     CONN_OPTION("readdirplus=yes", no_readdirplus_auto, 1),
 122     CONN_OPTION("readdirplus=auto", no_readdirplus, 0),
 123     CONN_OPTION("readdirplus=auto", no_readdirplus_auto, 0),
 124     CONN_OPTION("async_dio", async_dio, 1),
 125     CONN_OPTION("no_async_dio", no_async_dio, 1),
 126     CONN_OPTION("writeback_cache", writeback_cache, 1),
 127     CONN_OPTION("no_writeback_cache", no_writeback_cache, 1),
 128     CONN_OPTION("time_gran=%u", time_gran, 0),
 129     CONN_OPTION("time_gran=", set_time_gran, 1),
 130     FUSE_OPT_END
 131 };
 132
 133
 134 void fuse_cmdline_help(void)
 135 {
 136     printf("    -h   --help                print help\n"
 137            "    -V   --version             print version\n"
 138            "    --print-capabilities       print vhost-user.json\n"
 139            "    -d   -o debug              enable debug output (implies -f)\n"
 140            "    --syslog                   log to syslog (default stderr)\n"
 141            "    -f                         foreground operation\n"
 142            "    --daemonize                run in background\n"
 143            "    -o cache=<mode>            cache mode. could be one of \"auto, "
 144            "always, none\"\n"
 145            "                               default: auto\n"
 146            "    -o flock|no_flock          enable/disable flock\n"
 147            "                               default: no_flock\n"
 148            "    -o log_level=<level>       log level, default to \"info\"\n"
 149            "                               level could be one of \"debug, "
 150            "info, warn, err\"\n"
 151            "    -o max_idle_threads        the maximum number of idle worker "
 152            "threads\n"
 153            "                               allowed (default: 10)\n"
 154            "    -o posix_lock|no_posix_lock\n"
 155            "                               enable/disable remote posix lock\n"
 156            "                               default: no_posix_lock\n"
 157            "    -o readdirplus|no_readdirplus\n"
 158            "                               enable/disable readirplus\n"
 159            "                               default: readdirplus except with "
 160            "cache=none\n"
 161            "    -o sandbox=namespace|chroot\n"
 162            "                               sandboxing mode:\n"
 163            "                               - namespace: mount, pid, and net\n"
 164            "                                 namespaces with pivot_root(2)\n"
 165            "                                 into shared directory\n"
 166            "                               - chroot: chroot(2) into shared\n"
 167            "                                 directory (use in containers)\n"
 168            "                               default: namespace\n"
 169            "    -o timeout=<number>        I/O timeout (seconds)\n"
 170            "                               default: depends on cache= option.\n"
 171            "    -o writeback|no_writeback  enable/disable writeback cache\n"
 172            "                               default: no_writeback\n"
 173            "    -o xattr|no_xattr          enable/disable xattr\n"
 174            "                               default: no_xattr\n"
 175            "    -o xattrmap=<mapping>      Enable xattr mapping (enables xattr)\n"
 176            "                               <mapping> is a string consists of a series of rules\n"
 177            "                               e.g. -o xattrmap=:map::user.virtiofs.:\n"
 178            "    -o modcaps=CAPLIST         Modify the list of capabilities\n"
 179            "                               e.g. -o modcaps=+sys_admin:-chown\n"
 180            "    --rlimit-nofile=<num>      set maximum number of file descriptors\n"
 181            "                               (0 leaves rlimit unchanged)\n"
 182            "                               default: min(1000000, fs.file-max - 16384)\n"
 183            "                                        if the current rlimit is lower\n"
 184            "    -o allow_direct_io|no_allow_direct_io\n"
 185            "                               retain/discard O_DIRECT flags passed down\n"
 186            "                               to virtiofsd from guest applications.\n"
 187            "                               default: no_allow_direct_io\n"
 188            "    -o announce_submounts      Announce sub-mount points to the guest\n"
 189            );
 190 }
 191
 192 static int fuse_helper_opt_proc(void *data, const char *arg, int key,
 193                                 struct fuse_args *outargs)
 194 {
 195     (void)data;
 196     (void)outargs;
 197
 198     switch (key) {
 199     case FUSE_OPT_KEY_NONOPT:
 200         fuse_log(FUSE_LOG_ERR, "fuse: invalid argument `%s'\n", arg);
 201         return -1;
 202
 203     default:
 204         /* Pass through unknown options */
 205         return 1;
 206     }
 207 }
 208
 209 static unsigned long get_default_rlimit_nofile(void)
 210 {
 211     g_autofree gchar *file_max_str = NULL;
 212     const rlim_t reserved_fds = 16384; /* leave at least this many fds free */
 213     rlim_t max_fds = 1000000; /* our default RLIMIT_NOFILE target */
 214     rlim_t file_max;
 215     struct rlimit rlim;
 216
 217     /*
 218      * Reduce max_fds below the system-wide maximum, if necessary.  This
 219      * ensures there are fds available for other processes so we don't
 220      * cause resource exhaustion.
 221      */
 222     if (!g_file_get_contents("/proc/sys/fs/file-max", &file_max_str,
 223                              NULL, NULL)) {
 224         fuse_log(FUSE_LOG_ERR, "can't read /proc/sys/fs/file-max\n");
 225         exit(1);
 226     }
 227     file_max = g_ascii_strtoull(file_max_str, NULL, 10);
 228     if (file_max < 2 * reserved_fds) {
 229         fuse_log(FUSE_LOG_ERR,
 230                  "The fs.file-max sysctl is too low (%lu) to allow a "
 231                  "reasonable number of open files.\n",
 232                  (unsigned long)file_max);
 233         exit(1);
 234     }
 235     max_fds = MIN(file_max - reserved_fds, max_fds);
 236
 237     if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
 238         fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
 239         exit(1);
 240     }
 241
 242     if (rlim.rlim_cur >= max_fds) {
 243         return 0; /* we have more fds available than required! */
 244     }
 245     return max_fds;
 246 }
 247
 248 int fuse_parse_cmdline(struct fuse_args *args, struct fuse_cmdline_opts *opts)
 249 {
 250     memset(opts, 0, sizeof(struct fuse_cmdline_opts));
 251
 252     opts->max_idle_threads = 10;
 253     opts->rlimit_nofile = get_default_rlimit_nofile();
 254     opts->foreground = 1;
 255
 256     if (fuse_opt_parse(args, opts, fuse_helper_opts, fuse_helper_opt_proc) ==
 257         -1) {
 258         return -1;
 259     }
 260
 261     return 0;
 262 }
 263
 264
 265 int fuse_daemonize(int foreground)
 266 {
 267     int ret = 0, rett;
 268     if (!foreground) {
 269         int nullfd;
 270         int waiter[2];
 271         char completed;
 272
 273         if (pipe(waiter)) {
 274             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: pipe: %s\n",
 275                      strerror(errno));
 276             return -1;
 277         }
 278
 279         /*
 280          * demonize current process by forking it and killing the
 281          * parent.  This makes current process as a child of 'init'.
 282          */
 283         switch (fork()) {
 284         case -1:
 285             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: fork: %s\n",
 286                      strerror(errno));
 287             return -1;
 288         case 0:
 289             break;
 290         default:
 291             _exit(read(waiter[0], &completed,
 292                        sizeof(completed) != sizeof(completed)));
 293         }
 294
 295         if (setsid() == -1) {
 296             fuse_log(FUSE_LOG_ERR, "fuse_daemonize: setsid: %s\n",
 297                      strerror(errno));
 298             return -1;
 299         }
 300
 301         ret = chdir("/");
 302
 303         nullfd = open("/dev/null", O_RDWR, 0);
 304         if (nullfd != -1) {
 305             rett = dup2(nullfd, 0);
 306             if (!ret) {
 307                 ret = rett;
 308             }
 309             rett = dup2(nullfd, 1);
 310             if (!ret) {
 311                 ret = rett;
 312             }
 313             rett = dup2(nullfd, 2);
 314             if (!ret) {
 315                 ret = rett;
 316             }
 317             if (nullfd > 2) {
 318                 close(nullfd);
 319             }
 320         }
 321
 322         /* Propagate completion of daemon initialization */
 323         completed = 1;
 324         rett = write(waiter[1], &completed, sizeof(completed));
 325         if (!ret) {
 326             ret = rett;
 327         }
 328         close(waiter[0]);
 329         close(waiter[1]);
 330     } else {
 331         ret = chdir("/");
 332     }
 333     return ret;
 334 }
 335
 336 void fuse_apply_conn_info_opts(struct fuse_conn_info_opts *opts,
 337                                struct fuse_conn_info *conn)
 338 {
 339     if (opts->set_max_write) {
 340         conn->max_write = opts->max_write;
 341     }
 342     if (opts->set_max_background) {
 343         conn->max_background = opts->max_background;
 344     }
 345     if (opts->set_congestion_threshold) {
 346         conn->congestion_threshold = opts->congestion_threshold;
 347     }
 348     if (opts->set_time_gran) {
 349         conn->time_gran = opts->time_gran;
 350     }
 351     if (opts->set_max_readahead) {
 352         conn->max_readahead = opts->max_readahead;
 353     }
 354
 355 #define LL_ENABLE(cond, cap) \
 356     if (cond)                \
 357         conn->want |= (cap)
 358 #define LL_DISABLE(cond, cap) \
 359     if (cond)                 \
 360         conn->want &= ~(cap)
 361
 362     LL_ENABLE(opts->splice_read, FUSE_CAP_SPLICE_READ);
 363     LL_DISABLE(opts->no_splice_read, FUSE_CAP_SPLICE_READ);
 364
 365     LL_ENABLE(opts->splice_write, FUSE_CAP_SPLICE_WRITE);
 366     LL_DISABLE(opts->no_splice_write, FUSE_CAP_SPLICE_WRITE);
 367
 368     LL_ENABLE(opts->splice_move, FUSE_CAP_SPLICE_MOVE);
 369     LL_DISABLE(opts->no_splice_move, FUSE_CAP_SPLICE_MOVE);
 370
 371     LL_ENABLE(opts->auto_inval_data, FUSE_CAP_AUTO_INVAL_DATA);
 372     LL_DISABLE(opts->no_auto_inval_data, FUSE_CAP_AUTO_INVAL_DATA);
 373
 374     LL_DISABLE(opts->no_readdirplus, FUSE_CAP_READDIRPLUS);
 375     LL_DISABLE(opts->no_readdirplus_auto, FUSE_CAP_READDIRPLUS_AUTO);
 376
 377     LL_ENABLE(opts->async_dio, FUSE_CAP_ASYNC_DIO);
 378     LL_DISABLE(opts->no_async_dio, FUSE_CAP_ASYNC_DIO);
 379
 380     LL_ENABLE(opts->writeback_cache, FUSE_CAP_WRITEBACK_CACHE);
 381     LL_DISABLE(opts->no_writeback_cache, FUSE_CAP_WRITEBACK_CACHE);
 382
 383     LL_ENABLE(opts->async_read, FUSE_CAP_ASYNC_READ);
 384     LL_DISABLE(opts->sync_read, FUSE_CAP_ASYNC_READ);
 385
 386     LL_DISABLE(opts->no_remote_posix_lock, FUSE_CAP_POSIX_LOCKS);
 387     LL_DISABLE(opts->no_remote_flock, FUSE_CAP_FLOCK_LOCKS);
 388 }
 389
 390 struct fuse_conn_info_opts *fuse_parse_conn_info_opts(struct fuse_args *args)
 391 {
 392     struct fuse_conn_info_opts *opts;
 393
 394     opts = calloc(1, sizeof(struct fuse_conn_info_opts));
 395     if (opts == NULL) {
 396         fuse_log(FUSE_LOG_ERR, "calloc failed\n");
 397         return NULL;
 398     }
 399     if (fuse_opt_parse(args, opts, conn_info_opt_spec, NULL) == -1) {
 400         free(opts);
 401         return NULL;
 402     }
 403     return opts;
 404 }