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