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
10 USE_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
13 config 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
GLOBALS(struct arg_list * optlist;char * type;char * bigO;unsigned long flags;char * opts;int okuser;)50 GLOBALS(
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,.
80 static 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
mount_filesystem(char * dev,char * dir,char * type,unsigned long flags,char * opts)138 static 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) break;
183 type = buf;
184 // skip nodev devices
185 if (!isspace(*type)) {
186 free(buf);
187 buf = 0;
188
189 continue;
190 }
191 // trim whitespace
192 while (isspace(*type)) type++;
193 i = strlen(type);
194 if (i) type[i-1] = 0;
195 }
196 if (toys.optflags & FLAG_v)
197 printf("try '%s' type '%s' on '%s'\n", dev, type, dir);
198 for (;;) {
199 rc = mount(dev, dir, type, flags, opts);
200 // Did we succeed, fail unrecoverably, or already try read-only?
201 if (!rc || (errno != EACCES && errno != EROFS) || (flags&MS_RDONLY))
202 break;
203 // If we haven't already tried it, use the BLKROSET ioctl to ensure
204 // that the underlying device isn't read-only.
205 if (fd == -1) {
206 if (toys.optflags & FLAG_v)
207 printf("trying BLKROSET ioctl on '%s'\n", dev);
208 if (-1 != (fd = open(dev, O_RDONLY))) {
209 rc = ioctl(fd, BLKROSET, &ro);
210 close(fd);
211 if (!rc) continue;
212 }
213 }
214 fprintf(stderr, "'%s' is read-only\n", dev);
215 flags |= MS_RDONLY;
216 }
217
218 // Trying to autodetect loop mounts like bind mounts above (file on dir)
219 // isn't good enough because "mount -t ext2 fs.img dir" is valid, but if
220 // you _do_ accept loop mounts with -t how do you tell "-t cifs" isn't
221 // looking for a block device if it's not in /proc/filesystems yet
222 // because the module that won't be loaded until you try the mount, and
223 // if you can't then DEVICE existing as a file would cause a false
224 // positive loopback mount (so "touch servername" becomes a potential
225 // denial of service attack...)
226 //
227 // Solution: try the mount, let the kernel tell us it wanted a block
228 // device, then do the loopback setup and retry the mount.
229
230 if (rc && errno == ENOTBLK) {
231 char *losetup[] = {"losetup", "-fs", dev, 0};
232 int pipe, len;
233 pid_t pid;
234
235 if (flags & MS_RDONLY) losetup[1] = "-fsr";
236 pid = xpopen(losetup, &pipe, 1);
237 len = readall(pipe, toybuf, sizeof(toybuf)-1);
238 rc = xpclose(pid, pipe);
239 if (!rc && len > 1) {
240 if (toybuf[len-1] == '\n') --len;
241 toybuf[len] = 0;
242 dev = toybuf;
243
244 continue;
245 }
246 error_msg("losetup failed %d", rc);
247
248 break;
249 }
250
251 free(buf);
252 buf = 0;
253 if (!rc) break;
254 if (fp && (errno == EINVAL || errno == EBUSY)) continue;
255
256 perror_msg("'%s'->'%s'", dev, dir);
257
258 break;
259 }
260 if (fp) fclose(fp);
261 }
262
mount_main(void)263 void mount_main(void)
264 {
265 char *opts = 0, *dev = 0, *dir = 0, **ss;
266 long flags = MS_SILENT;
267 struct arg_list *o;
268 struct mtab_list *mtl, *mtl2 = 0, *mm, *remount;
269
270 // TODO
271 // remount
272 // - overmounts
273 // shared subtree
274 // -o parsed after fstab options
275 // test if mountpoint already exists (-o noremount?)
276
277 // First pass; just accumulate string, don't parse flags yet. (This is so
278 // we can modify fstab entries with -a, or mtab with remount.)
279 for (o = TT.optlist; o; o = o->next) comma_collate(&opts, o->arg);
280 if (toys.optflags & FLAG_r) comma_collate(&opts, "ro");
281 if (toys.optflags & FLAG_w) comma_collate(&opts, "rw");
282
283 // Treat each --option as -o option
284 for (ss = toys.optargs; *ss; ss++) {
285 char *sss = *ss;
286
287 // If you realy, really want to mount a file named "--", we support it.
288 if (sss[0]=='-' && sss[1]=='-' && sss[2]) comma_collate(&opts, sss+2);
289 else if (!dev) dev = sss;
290 else if (!dir) dir = sss;
291 // same message as lib/args.c ">2" which we can't use because --opts count
292 else error_exit("Max 2 arguments\n");
293 }
294
295 if ((toys.optflags & FLAG_a) && dir) error_exit("-a with >1 arg");
296
297 // For remount we need _last_ match (in case of overmounts), so traverse
298 // in reverse order. (Yes I'm using remount as a boolean for a bit here,
299 // the double cast is to get gcc to shut up about it.)
300 remount = (void *)(long)comma_scan(opts, "remount", 1);
301 if (((toys.optflags & FLAG_a) && !access("/proc/mounts", R_OK)) || remount) {
302 mm = dlist_terminate(mtl = mtl2 = xgetmountlist(0));
303 if (remount) remount = mm;
304 }
305
306 // Do we need to do an /etc/fstab trawl?
307 // This covers -a, -o remount, one argument, all user mounts
308 if ((toys.optflags & FLAG_a) || (dev && (!dir || getuid() || remount))) {
309 if (!remount) dlist_terminate(mtl = xgetmountlist("/etc/fstab"));
310
311 for (mm = remount ? remount : mtl; mm; mm = (remount ? mm->prev : mm->next))
312 {
313 char *aopts = 0;
314 struct mtab_list *mmm = 0;
315 int aflags, noauto, len;
316
317 // Check for noauto and get it out of the option list. (Unknown options
318 // that make it to the kernel give filesystem drivers indigestion.)
319 noauto = comma_scan(mm->opts, "noauto", 1);
320
321 if (toys.optflags & FLAG_a) {
322 // "mount -a /path" to mount all entries under /path
323 if (dev) {
324 len = strlen(dev);
325 if (strncmp(dev, mm->dir, len)
326 || (mm->dir[len] && mm->dir[len] != '/')) continue;
327 } else if (noauto) continue; // never present in the remount case
328 if (!mountlist_istype(mm,TT.type) || !comma_scanall(mm->opts,TT.bigO))
329 continue;
330 } else {
331 if (dir && strcmp(dir, mm->dir)) continue;
332 if (dev && strcmp(dev, mm->device) && (dir || strcmp(dev, mm->dir)))
333 continue;
334 }
335
336 // Don't overmount the same dev on the same directory
337 // (Unless root explicitly says to in non -a mode.)
338 if (mtl2 && !remount)
339 for (mmm = mtl2; mmm; mmm = mmm->next)
340 if (!strcmp(mm->dir, mmm->dir) && !strcmp(mm->device, mmm->device))
341 break;
342
343 // user only counts from fstab, not opts.
344 if (!mmm) {
345 TT.okuser = comma_scan(mm->opts, "user", 1);
346 aflags = flag_opts(mm->opts, flags, &aopts);
347 aflags = flag_opts(opts, aflags, &aopts);
348
349 mount_filesystem(mm->device, mm->dir, mm->type, aflags, aopts);
350 } // TODO else if (getuid()) error_msg("already there") ?
351 free(aopts);
352
353 if (!(toys.optflags & FLAG_a)) break;
354 }
355 if (CFG_TOYBOX_FREE) {
356 llist_traverse(mtl, free);
357 llist_traverse(mtl2, free);
358 }
359 if (!mm && !(toys.optflags & FLAG_a))
360 error_exit("'%s' not in %s", dir ? dir : dev,
361 remount ? "/proc/mounts" : "fstab");
362
363 // show mounts from /proc/mounts
364 } else if (!dev) {
365 for (mtl = xgetmountlist(0); mtl && (mm = dlist_pop(&mtl)); free(mm)) {
366 char *s = 0;
367
368 if (TT.type && strcmp(TT.type, mm->type)) continue;
369 if (*mm->device == '/') s = xabspath(mm->device, 0);
370 xprintf("%s on %s type %s (%s)\n",
371 s ? s : mm->device, mm->dir, mm->type, mm->opts);
372 free(s);
373 }
374
375 // two arguments
376 } else {
377 char *more = 0;
378
379 flags = flag_opts(opts, flags, &more);
380 mount_filesystem(dev, dir, TT.type, flags, more);
381 if (CFG_TOYBOX_FREE) free(more);
382 }
383 }
384