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