1/* mount.c - mount filesystems 2 * 3 * Copyright 2014 Rob Landley <rob@landley.net> 4 * 5 * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/mount.html 6 * Note: -hV is bad spec, haven't implemented -FsLU yet 7 * no mtab (/proc/mounts does it) so -n is NOP. 8 * TODO mount -o loop,autoclear (linux git 96c5865559ce) 9 10USE_MOUNT(NEWTOY(mount, "?O:afnrvwt:o*[-rw]", TOYFLAG_BIN|TOYFLAG_STAYROOT)) 11//USE_NFSMOUNT(NEWTOY(nfsmount, "?<2>2", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT)) 12 13config MOUNT 14 bool "mount" 15 default y 16 help 17 usage: mount [-afFrsvw] [-t TYPE] [-o OPTION,] [[DEVICE] DIR] 18 19 Mount new filesystem(s) on directories. With no arguments, display existing 20 mounts. 21 22 -a mount all entries in /etc/fstab (with -t, only entries of that TYPE) 23 -O only mount -a entries that have this option 24 -f fake it (don't actually mount) 25 -r read only (same as -o ro) 26 -w read/write (default, same as -o rw) 27 -t specify filesystem type 28 -v verbose 29 30 OPTIONS is a comma separated list of options, which can also be supplied 31 as --longopts. 32 33 This mount autodetects loopback mounts (a file on a directory) and 34 bind mounts (file on file, directory on directory), so you don't need 35 to say --bind or --loop. You can also "mount -a /path" to mount everything 36 in /etc/fstab under /path, even if it's noauto. 37 38#config NFSMOUNT 39# bool "nfsmount" 40# default n 41# help 42# usage: nfsmount SHARE DIR 43# 44# Invoke an eldrich horror from the dawn of time. 45*/ 46 47#define FOR_mount 48#include "toys.h" 49 50GLOBALS( 51 struct arg_list *optlist; 52 char *type; 53 char *bigO; 54 55 unsigned long flags; 56 char *opts; 57 int okuser; 58) 59 60// mount.tests should check for all of this: 61// TODO detect existing identical mount (procfs with different dev name?) 62// TODO user, users, owner, group, nofail 63// TODO -p (passfd) 64// TODO -a -t notype,type2 65// TODO --subtree 66// TODO --rbind, -R 67// TODO make "mount --bind,ro old new" work (implicit -o remount) 68// TODO mount -a 69// TODO mount -o remount 70// TODO fstab: lookup default options for mount 71// TODO implement -v 72// TODO "mount -a -o remount,ro" should detect overmounts 73// TODO work out how that differs from "mount -ar" 74// TODO what if you --bind mount a block device somewhere (file, dir, dev) 75// TODO "touch servername; mount -t cifs servername path" 76// TODO mount -o remount a user mount 77// TODO mount image.img sub (auto-loopback) then umount image.img 78 79// Strip flags out of comma separated list of options, return flags,. 80static long flag_opts(char *new, long flags, char **more) 81{ 82 struct { 83 char *name; 84 long flags; 85 } opts[] = { 86 // NOPs (we autodetect --loop and --bind) 87 {"loop", 0}, {"bind", 0}, {"defaults", 0}, {"quiet", 0}, 88 {"user", 0}, {"nouser", 0}, // checked in fstab, ignored in -o 89 {"ro", MS_RDONLY}, {"rw", ~MS_RDONLY}, 90 {"nosuid", MS_NOSUID}, {"suid", ~MS_NOSUID}, 91 {"nodev", MS_NODEV}, {"dev", ~MS_NODEV}, 92 {"noexec", MS_NOEXEC}, {"exec", ~MS_NOEXEC}, 93 {"sync", MS_SYNCHRONOUS}, {"async", ~MS_SYNCHRONOUS}, 94 {"noatime", MS_NOATIME}, {"atime", ~MS_NOATIME}, 95 {"norelatime", ~MS_RELATIME}, {"relatime", MS_RELATIME}, 96 {"nodiratime", MS_NODIRATIME}, {"diratime", ~MS_NODIRATIME}, 97 {"loud", ~MS_SILENT}, 98 {"shared", MS_SHARED}, {"rshared", MS_SHARED|MS_REC}, 99 {"slave", MS_SLAVE}, {"rslave", MS_SLAVE|MS_REC}, 100 {"private", MS_PRIVATE}, {"rprivate", MS_SLAVE|MS_REC}, 101 {"unbindable", MS_UNBINDABLE}, {"runbindable", MS_UNBINDABLE|MS_REC}, 102 {"remount", MS_REMOUNT}, {"move", MS_MOVE}, 103 // mand dirsync rec iversion strictatime 104 }; 105 106 if (new) for (;;) { 107 char *comma = strchr(new, ','); 108 int i; 109 110 if (comma) *comma = 0; 111 112 // If we recognize an option, apply flags 113 for (i = 0; i < ARRAY_LEN(opts); i++) if (!strcasecmp(opts[i].name, new)) { 114 long ll = opts[i].flags; 115 116 if (ll < 0) flags &= ll; 117 else flags |= ll; 118 119 break; 120 } 121 122 // If we didn't recognize it, keep string version 123 if (more && i == ARRAY_LEN(opts)) { 124 i = *more ? strlen(*more) : 0; 125 *more = xrealloc(*more, i + strlen(new) + 2); 126 if (i) (*more)[i++] = ','; 127 strcpy(i+*more, new); 128 } 129 130 if (!comma) break; 131 *comma = ','; 132 new = comma + 1; 133 } 134 135 return flags; 136} 137 138static void mount_filesystem(char *dev, char *dir, char *type, 139 unsigned long flags, char *opts) 140{ 141 FILE *fp = 0; 142 int rc = EINVAL; 143 char *buf = 0; 144 145 if (toys.optflags & FLAG_f) return; 146 147 if (getuid()) { 148 if (TT.okuser) TT.okuser = 0; 149 else { 150 error_msg("'%s' not user mountable in fstab", dev); 151 152 return; 153 } 154 } 155 156 // Autodetect bind mount or filesystem type 157 158 if (type && !strcmp(type, "auto")) type = 0; 159 if (flags & MS_MOVE) { 160 if (type) error_exit("--move with -t"); 161 } else if (!type) { 162 struct stat stdev, stdir; 163 164 // file on file or dir on dir is a --bind mount. 165 if (!stat(dev, &stdev) && !stat(dir, &stdir) 166 && ((S_ISREG(stdev.st_mode) && S_ISREG(stdir.st_mode)) 167 || (S_ISDIR(stdev.st_mode) && S_ISDIR(stdir.st_mode)))) 168 { 169 flags |= MS_BIND; 170 } else fp = xfopen("/proc/filesystems", "r"); 171 } else if (!strcmp(type, "ignore")) return; 172 else if (!strcmp(type, "swap")) 173 toys.exitval |= xrun((char *[]){"swapon", "--", dev, 0}); 174 175 for (;;) { 176 int fd = -1, ro = 0; 177 178 // If type wasn't specified, try all of them in order. 179 if (fp && !buf) { 180 size_t i; 181 182 if (getline(&buf, &i, fp)<0) { 183 error_msg("%s: need -t", dev); 184 break; 185 } 186 type = buf; 187 // skip nodev devices 188 if (!isspace(*type)) { 189 free(buf); 190 buf = 0; 191 192 continue; 193 } 194 // trim whitespace 195 while (isspace(*type)) type++; 196 i = strlen(type); 197 if (i) type[i-1] = 0; 198 } 199 if (toys.optflags & FLAG_v) 200 printf("try '%s' type '%s' on '%s'\n", dev, type, dir); 201 for (;;) { 202 rc = mount(dev, dir, type, flags, opts); 203 // Did we succeed, fail unrecoverably, or already try read-only? 204 if (!rc || (errno != EACCES && errno != EROFS) || (flags&MS_RDONLY)) 205 break; 206 // If we haven't already tried it, use the BLKROSET ioctl to ensure 207 // that the underlying device isn't read-only. 208 if (fd == -1) { 209 if (toys.optflags & FLAG_v) 210 printf("trying BLKROSET ioctl on '%s'\n", dev); 211 if (-1 != (fd = open(dev, O_RDONLY))) { 212 rc = ioctl(fd, BLKROSET, &ro); 213 close(fd); 214 if (!rc) continue; 215 } 216 } 217 fprintf(stderr, "'%s' is read-only\n", dev); 218 flags |= MS_RDONLY; 219 } 220 221 // Trying to autodetect loop mounts like bind mounts above (file on dir) 222 // isn't good enough because "mount -t ext2 fs.img dir" is valid, but if 223 // you _do_ accept loop mounts with -t how do you tell "-t cifs" isn't 224 // looking for a block device if it's not in /proc/filesystems yet 225 // because the module that won't be loaded until you try the mount, and 226 // if you can't then DEVICE existing as a file would cause a false 227 // positive loopback mount (so "touch servername" becomes a potential 228 // denial of service attack...) 229 // 230 // Solution: try the mount, let the kernel tell us it wanted a block 231 // device, then do the loopback setup and retry the mount. 232 233 if (rc && errno == ENOTBLK) { 234 char *losetup[] = {"losetup", "-fs", dev, 0}; 235 int pipe, len; 236 pid_t pid; 237 238 if (flags & MS_RDONLY) losetup[1] = "-fsr"; 239 pid = xpopen(losetup, &pipe, 1); 240 len = readall(pipe, toybuf, sizeof(toybuf)-1); 241 rc = xpclose(pid, pipe); 242 if (!rc && len > 1) { 243 if (toybuf[len-1] == '\n') --len; 244 toybuf[len] = 0; 245 dev = toybuf; 246 247 continue; 248 } 249 error_msg("losetup failed %d", rc); 250 251 break; 252 } 253 254 free(buf); 255 buf = 0; 256 if (!rc) break; 257 if (fp && (errno == EINVAL || errno == EBUSY)) continue; 258 259 perror_msg("'%s'->'%s'", dev, dir); 260 261 break; 262 } 263 if (fp) fclose(fp); 264} 265 266void mount_main(void) 267{ 268 char *opts = 0, *dev = 0, *dir = 0, **ss; 269 long flags = MS_SILENT; 270 struct arg_list *o; 271 struct mtab_list *mtl, *mtl2 = 0, *mm, *remount; 272 273// TODO 274// remount 275// - overmounts 276// shared subtree 277// -o parsed after fstab options 278// test if mountpoint already exists (-o noremount?) 279 280 // First pass; just accumulate string, don't parse flags yet. (This is so 281 // we can modify fstab entries with -a, or mtab with remount.) 282 for (o = TT.optlist; o; o = o->next) comma_collate(&opts, o->arg); 283 if (toys.optflags & FLAG_r) comma_collate(&opts, "ro"); 284 if (toys.optflags & FLAG_w) comma_collate(&opts, "rw"); 285 286 // Treat each --option as -o option 287 for (ss = toys.optargs; *ss; ss++) { 288 char *sss = *ss; 289 290 // If you realy, really want to mount a file named "--", we support it. 291 if (sss[0]=='-' && sss[1]=='-' && sss[2]) comma_collate(&opts, sss+2); 292 else if (!dev) dev = sss; 293 else if (!dir) dir = sss; 294 // same message as lib/args.c ">2" which we can't use because --opts count 295 else error_exit("Max 2 arguments\n"); 296 } 297 298 if ((toys.optflags & FLAG_a) && dir) error_exit("-a with >1 arg"); 299 300 // For remount we need _last_ match (in case of overmounts), so traverse 301 // in reverse order. (Yes I'm using remount as a boolean for a bit here, 302 // the double cast is to get gcc to shut up about it.) 303 remount = (void *)(long)comma_scan(opts, "remount", 0); 304 if (((toys.optflags & FLAG_a) && !access("/proc/mounts", R_OK)) || remount) { 305 mm = dlist_terminate(mtl = mtl2 = xgetmountlist(0)); 306 if (remount) remount = mm; 307 } 308 309 // Do we need to do an /etc/fstab trawl? 310 // This covers -a, -o remount, one argument, all user mounts 311 if ((toys.optflags & FLAG_a) || (dev && (!dir || getuid() || remount))) { 312 if (!remount) dlist_terminate(mtl = xgetmountlist("/etc/fstab")); 313 314 for (mm = remount ? remount : mtl; mm; mm = (remount ? mm->prev : mm->next)) 315 { 316 char *aopts = 0; 317 struct mtab_list *mmm = 0; 318 int aflags, noauto, len; 319 320 // Check for noauto and get it out of the option list. (Unknown options 321 // that make it to the kernel give filesystem drivers indigestion.) 322 noauto = comma_scan(mm->opts, "noauto", 1); 323 324 if (toys.optflags & FLAG_a) { 325 // "mount -a /path" to mount all entries under /path 326 if (dev) { 327 len = strlen(dev); 328 if (strncmp(dev, mm->dir, len) 329 || (mm->dir[len] && mm->dir[len] != '/')) continue; 330 } else if (noauto) continue; // never present in the remount case 331 if (!mountlist_istype(mm,TT.type) || !comma_scanall(mm->opts,TT.bigO)) 332 continue; 333 } else { 334 if (dir && strcmp(dir, mm->dir)) continue; 335 if (dev && strcmp(dev, mm->device) && (dir || strcmp(dev, mm->dir))) 336 continue; 337 } 338 339 // Don't overmount the same dev on the same directory 340 // (Unless root explicitly says to in non -a mode.) 341 if (mtl2 && !remount) 342 for (mmm = mtl2; mmm; mmm = mmm->next) 343 if (!strcmp(mm->dir, mmm->dir) && !strcmp(mm->device, mmm->device)) 344 break; 345 346 // user only counts from fstab, not opts. 347 if (!mmm) { 348 TT.okuser = comma_scan(mm->opts, "user", 1); 349 aflags = flag_opts(mm->opts, flags, &aopts); 350 aflags = flag_opts(opts, aflags, &aopts); 351 352 mount_filesystem(mm->device, mm->dir, mm->type, aflags, aopts); 353 } // TODO else if (getuid()) error_msg("already there") ? 354 free(aopts); 355 356 if (!(toys.optflags & FLAG_a)) break; 357 } 358 if (CFG_TOYBOX_FREE) { 359 llist_traverse(mtl, free); 360 llist_traverse(mtl2, free); 361 } 362 if (!mm && !(toys.optflags & FLAG_a)) 363 error_exit("'%s' not in %s", dir ? dir : dev, 364 remount ? "/proc/mounts" : "fstab"); 365 366 // show mounts from /proc/mounts 367 } else if (!dev) { 368 for (mtl = xgetmountlist(0); mtl && (mm = dlist_pop(&mtl)); free(mm)) { 369 char *s = 0; 370 371 if (TT.type && strcmp(TT.type, mm->type)) continue; 372 if (*mm->device == '/') s = xabspath(mm->device, 0); 373 xprintf("%s on %s type %s (%s)\n", 374 s ? s : mm->device, mm->dir, mm->type, mm->opts); 375 free(s); 376 } 377 378 // two arguments 379 } else { 380 char *more = 0; 381 382 flags = flag_opts(opts, flags, &more); 383 mount_filesystem(dev, dir, TT.type, flags, more); 384 if (CFG_TOYBOX_FREE) free(more); 385 } 386} 387