/* Check, if there already exists a mounted loop device on the mountpoint node
* with the same parameters.
*/
static int is_mounted_same_loopfile(struct libmnt_context *cxt,
const char *target,
const char *backing_file,
uint64_t offset)
{
struct libmnt_table *tb;
struct libmnt_iter itr;
struct libmnt_fs *fs;
struct libmnt_cache *cache;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
if (!target || !backing_file || mnt_context_get_mtab(cxt, &tb))
return 0;
DBG(CXT, mnt_debug_h(cxt, "checking if %s mounted on %s",
backing_file, target));
cache = mnt_context_get_cache(cxt);
mnt_reset_iter(&itr, MNT_ITER_BACKWARD);
/* Search for mountpoint node in mtab, procceed if any of these has the
* loop option set or the device is a loop device
*/
while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
const char *src = mnt_fs_get_source(fs);
const char *opts = mnt_fs_get_user_options(fs);
char *val;
size_t len;
int res = 0;
if (!src || !mnt_fs_match_target(fs, target, cache))
continue;
if (strncmp(src, "/dev/loop", 9) == 0) {
res = loopdev_is_used((char *) src, backing_file,
offset, LOOPDEV_FL_OFFSET);
} else if (opts && (cxt->user_mountflags & MNT_MS_LOOP) &&
mnt_optstr_get_option(opts, "loop", &val, &len) == 0 && val) {
val = strndup(val, len);
res = loopdev_is_used((char *) val, backing_file,
offset, LOOPDEV_FL_OFFSET);
free(val);
}
if (res) {
DBG(CXT, mnt_debug_h(cxt, "%s already mounted", backing_file));
return 1;
}
}
return 0;
}
/* Check if there is something important in the utab file. The parsed utab is
* stored in context->utab and deallocated by mnt_free_context().
*
* This function exists to avoid (if possible) /proc/self/mountinfo usage, so
* don't use thigs like mnt_resolve_target(), mnt_context_get_mtab() etc here.
* See lookup_umount_fs() for more details.
*/
static int has_utab_entry(struct libmnt_context *cxt, const char *target)
{
struct libmnt_cache *cache = NULL;
struct libmnt_fs *fs;
struct libmnt_iter itr;
char *cn = NULL;
int rc = 0;
assert(cxt);
if (!cxt->utab) {
const char *path = mnt_get_utab_path();
if (!path || is_file_empty(path))
return 0;
cxt->utab = mnt_new_table();
if (!cxt->utab)
return 0;
cxt->utab->fmt = MNT_FMT_UTAB;
if (mnt_table_parse_file(cxt->utab, path))
return 0;
}
/* paths in utab are canonicalized */
cache = mnt_context_get_cache(cxt);
cn = mnt_resolve_path(target, cache);
mnt_reset_iter(&itr, MNT_ITER_BACKWARD);
while (mnt_table_next_fs(cxt->utab, &itr, &fs) == 0) {
if (mnt_fs_streq_target(fs, cn)) {
rc = 1;
break;
}
}
if (!cache)
free(cn);
return rc;
}
static int lookup_umount_fs(struct libmnt_context *cxt)
{
int rc, loopdev = 0;
const char *tgt;
struct libmnt_table *mtab = NULL;
struct libmnt_fs *fs;
struct libmnt_cache *cache = NULL;
char *cn_tgt = NULL;
assert(cxt);
assert(cxt->fs);
DBG(CXT, mnt_debug_h(cxt, "umount: lookup FS"));
tgt = mnt_fs_get_target(cxt->fs);
if (!tgt) {
DBG(CXT, mnt_debug_h(cxt, "umount: undefined target"));
return -EINVAL;
}
/*
* The mtab file maybe huge and on systems with utab we have to merge
* userspace mount options into /proc/self/mountinfo. This all is
* expensive. The mtab filter allows to filter out entries, then
* mtab and utab are very tiny files.
*
* *but*... the filter uses mnt_fs_streq_{target,srcpath} functions
* where LABEL, UUID or symlinks are to canonicalized. It means that
* it's usable only for canonicalized stuff (e.g. kernel mountinfo).
*/
if (!cxt->mtab_writable && *tgt == '/' &&
!mnt_context_is_force(cxt) && !mnt_context_is_lazy(cxt)) {
struct stat st;
if (stat(tgt, &st) == 0 && S_ISDIR(st.st_mode)) {
/* we'll canonicalized /proc/self/mountinfo */
cache = mnt_context_get_cache(cxt);
cn_tgt = mnt_resolve_path(tgt, cache);
if (cn_tgt)
mnt_context_set_tabfilter(cxt, mtab_filter, cn_tgt);
}
}
rc = mnt_context_get_mtab(cxt, &mtab);
if (cn_tgt) {
mnt_context_set_tabfilter(cxt, NULL, NULL);
if (!cache)
free(cn_tgt);
}
if (rc) {
DBG(CXT, mnt_debug_h(cxt, "umount: failed to read mtab"));
return rc;
}
try_loopdev:
fs = mnt_table_find_target(mtab, tgt, MNT_ITER_BACKWARD);
if (!fs && mnt_context_is_swapmatch(cxt)) {
/*
* Maybe the option is source rather than target (sometimes
* people use e.g. "umount /dev/sda1")
*/
fs = mnt_table_find_source(mtab, tgt, MNT_ITER_BACKWARD);
if (fs) {
struct libmnt_fs *fs1 = mnt_table_find_target(mtab,
mnt_fs_get_target(fs),
MNT_ITER_BACKWARD);
if (!fs1) {
DBG(CXT, mnt_debug_h(cxt, "mtab is broken?!?!"));
return -EINVAL;
}
if (fs != fs1) {
/* Something was stacked over `file' on the
* same mount point. */
DBG(CXT, mnt_debug_h(cxt,
"umount: %s: %s is mounted "
"over it on the same point",
tgt, mnt_fs_get_source(fs1)));
return -EINVAL;
}
}
}
if (!fs && !loopdev && mnt_context_is_swapmatch(cxt)) {
/*
* Maybe the option is /path/file.img, try to convert to /dev/loopN
*/
struct stat st;
if (stat(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
char *dev = NULL;
int count = loopdev_count_by_backing_file(tgt, &dev);
if (count == 1) {
DBG(CXT, mnt_debug_h(cxt,
"umount: %s --> %s (retry)", tgt, dev));
mnt_fs_set_source(cxt->fs, tgt);
mnt_fs_set_target(cxt->fs, dev);
free(dev);
tgt = mnt_fs_get_target(cxt->fs);
loopdev = 1; /* to avoid endless loop */
goto try_loopdev;
} else if (count > 1)
DBG(CXT, mnt_debug_h(cxt,
"umount: warning: %s is associated "
"with more than one loopdev", tgt));
}
}
if (!fs) {
DBG(CXT, mnt_debug_h(cxt, "umount: cannot find %s in mtab", tgt));
return 0;
}
if (fs != cxt->fs) {
/* copy from mtab to our FS description
*/
mnt_fs_set_source(cxt->fs, NULL);
mnt_fs_set_target(cxt->fs, NULL);
if (!mnt_copy_fs(cxt->fs, fs)) {
DBG(CXT, mnt_debug_h(cxt, "umount: failed to copy FS"));
return -errno;
}
DBG(CXT, mnt_debug_h(cxt, "umount: mtab applied"));
}
cxt->flags |= MNT_FL_TAB_APPLIED;
return rc;
}
/**
* mnt_context_find_umount_fs:
* @cxt: mount context
* @tgt: mountpoint, device, ...
* @pfs: returns point to filesystem
*
* Returns: 0 on success, <0 on error, 1 if target filesystem not found
*/
int mnt_context_find_umount_fs(struct libmnt_context *cxt,
const char *tgt,
struct libmnt_fs **pfs)
{
int rc;
struct libmnt_table *mtab = NULL;
struct libmnt_fs *fs;
char *loopdev = NULL;
if (pfs)
*pfs = NULL;
if (!cxt || !tgt || !pfs)
return -EINVAL;
DBG(CXT, ul_debugobj(cxt, "umount: lookup FS for '%s'", tgt));
if (!*tgt)
return 1; /* empty string is not an error */
/*
* The mount table may be huge, and on systems with utab we have to merge
* userspace mount options into /proc/self/mountinfo. This all is
* expensive. The tab filter allows to filter out entries, then
* a mount table and utab are very tiny files.
*
* *but*... the filter uses mnt_fs_streq_{target,srcpath} functions
* where LABEL, UUID or symlinks are canonicalized. It means that
* it's usable only for canonicalized stuff (e.g. kernel mountinfo).
*/
if (!mnt_context_mtab_writable(cxt) && *tgt == '/' &&
!mnt_context_is_force(cxt) && !mnt_context_is_lazy(cxt))
rc = mnt_context_get_mtab_for_target(cxt, &mtab, tgt);
else
rc = mnt_context_get_mtab(cxt, &mtab);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "umount: failed to read mtab"));
return rc;
}
if (mnt_table_get_nents(mtab) == 0) {
DBG(CXT, ul_debugobj(cxt, "umount: mtab empty"));
return 1;
}
try_loopdev:
fs = mnt_table_find_target(mtab, tgt, MNT_ITER_BACKWARD);
if (!fs && mnt_context_is_swapmatch(cxt)) {
/*
* Maybe the option is source rather than target (sometimes
* people use e.g. "umount /dev/sda1")
*/
fs = mnt_table_find_source(mtab, tgt, MNT_ITER_BACKWARD);
if (fs) {
struct libmnt_fs *fs1 = mnt_table_find_target(mtab,
mnt_fs_get_target(fs),
MNT_ITER_BACKWARD);
if (!fs1) {
DBG(CXT, ul_debugobj(cxt, "mtab is broken?!?!"));
rc = -EINVAL;
goto err;
}
if (fs != fs1) {
/* Something was stacked over `file' on the
* same mount point. */
DBG(CXT, ul_debugobj(cxt,
"umount: %s: %s is mounted "
"over it on the same point",
tgt, mnt_fs_get_source(fs1)));
rc = -EINVAL;
goto err;
}
}
}
if (!fs && !loopdev && mnt_context_is_swapmatch(cxt)) {
/*
* Maybe the option is /path/file.img, try to convert to /dev/loopN
*/
struct stat st;
if (mnt_stat_mountpoint(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
int count;
struct libmnt_cache *cache = mnt_context_get_cache(cxt);
const char *bf = cache ? mnt_resolve_path(tgt, cache) : tgt;
count = loopdev_count_by_backing_file(bf, &loopdev);
if (count == 1) {
DBG(CXT, ul_debugobj(cxt,
"umount: %s --> %s (retry)", tgt, loopdev));
tgt = loopdev;
goto try_loopdev;
} else if (count > 1)
DBG(CXT, ul_debugobj(cxt,
"umount: warning: %s is associated "
"with more than one loopdev", tgt));
}
}
if (pfs)
*pfs = fs;
free(loopdev);
DBG(CXT, ul_debugobj(cxt, "umount fs: %s", fs ? mnt_fs_get_target(fs) :
"<not found>"));
return fs ? 0 : 1;
err:
free(loopdev);
return rc;
}
/*
* Note that cxt->fs contains relevant mtab entry!
*/
static int evaluate_permissions(struct libmnt_context *cxt)
{
struct libmnt_table *fstab;
unsigned long u_flags = 0;
const char *tgt, *src, *optstr;
int rc, ok = 0;
struct libmnt_fs *fs;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
if (!mnt_context_is_restricted(cxt))
return 0; /* superuser mount */
DBG(CXT, ul_debugobj(cxt, "umount: evaluating permissions"));
if (!mnt_context_tab_applied(cxt)) {
DBG(CXT, ul_debugobj(cxt,
"cannot find %s in mtab and you are not root",
mnt_fs_get_target(cxt->fs)));
goto eperm;
}
if (cxt->user_mountflags & MNT_MS_UHELPER) {
/* on uhelper= mount option based helper */
rc = prepare_helper_from_options(cxt, "uhelper");
if (rc)
return rc;
if (cxt->helper)
return 0; /* we'll call /sbin/umount.<uhelper> */
}
/*
* User mounts have to be in /etc/fstab
*/
rc = mnt_context_get_fstab(cxt, &fstab);
if (rc)
return rc;
tgt = mnt_fs_get_target(cxt->fs);
src = mnt_fs_get_source(cxt->fs);
if (mnt_fs_get_bindsrc(cxt->fs)) {
src = mnt_fs_get_bindsrc(cxt->fs);
DBG(CXT, ul_debugobj(cxt,
"umount: using bind source: %s", src));
}
/* If fstab contains the two lines
* /dev/sda1 /mnt/zip auto user,noauto 0 0
* /dev/sda4 /mnt/zip auto user,noauto 0 0
* then "mount /dev/sda4" followed by "umount /mnt/zip" used to fail.
* So, we must not look for the file, but for the pair (dev,file) in fstab.
*/
fs = mnt_table_find_pair(fstab, src, tgt, MNT_ITER_FORWARD);
if (!fs) {
/*
* It's possible that there is /path/file.img in fstab and
* /dev/loop0 in mtab -- then we have to check the relation
* between loopdev and the file.
*/
fs = mnt_table_find_target(fstab, tgt, MNT_ITER_FORWARD);
if (fs) {
struct libmnt_cache *cache = mnt_context_get_cache(cxt);
const char *sp = mnt_fs_get_srcpath(cxt->fs); /* devname from mtab */
const char *dev = sp && cache ? mnt_resolve_path(sp, cache) : sp;
if (!dev || !is_associated_fs(dev, fs))
fs = NULL;
}
if (!fs) {
DBG(CXT, ul_debugobj(cxt,
"umount %s: mtab disagrees with fstab",
tgt));
goto eperm;
}
}
/*
* User mounting and unmounting is allowed only if fstab contains one
* of the options `user', `users' or `owner' or `group'.
*
* The option `users' allows arbitrary users to mount and unmount -
* this may be a security risk.
*
* The options `user', `owner' and `group' only allow unmounting by the
* user that mounted (visible in mtab).
*/
optstr = mnt_fs_get_user_options(fs); /* FSTAB mount options! */
if (!optstr)
goto eperm;
if (mnt_optstr_get_flags(optstr, &u_flags,
mnt_get_builtin_optmap(MNT_USERSPACE_MAP)))
goto eperm;
if (u_flags & MNT_MS_USERS) {
DBG(CXT, ul_debugobj(cxt,
"umount: promiscuous setting ('users') in fstab"));
return 0;
}
/*
* Check user=<username> setting from mtab if there is a user, owner or
* group option in /etc/fstab
*/
if (u_flags & (MNT_MS_USER | MNT_MS_OWNER | MNT_MS_GROUP)) {
char *curr_user = NULL;
char *mtab_user = NULL;
size_t sz;
DBG(CXT, ul_debugobj(cxt,
"umount: checking user=<username> from mtab"));
curr_user = mnt_get_username(getuid());
if (!curr_user) {
DBG(CXT, ul_debugobj(cxt, "umount %s: cannot "
"convert %d to username", tgt, getuid()));
goto eperm;
}
/* get options from mtab */
optstr = mnt_fs_get_user_options(cxt->fs);
if (optstr && !mnt_optstr_get_option(optstr,
"user", &mtab_user, &sz) && sz)
ok = !strncmp(curr_user, mtab_user, sz);
free(curr_user);
}
if (ok) {
DBG(CXT, ul_debugobj(cxt, "umount %s is allowed", tgt));
return 0;
}
eperm:
DBG(CXT, ul_debugobj(cxt, "umount is not allowed for you"));
return -EPERM;
}
/*
* this has to be called before fix_optstr()
*/
static int evaluate_permissions(struct libmnt_context *cxt)
{
unsigned long u_flags = 0;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
if (!cxt)
return -EINVAL;
if (!cxt->fs)
return 0;
DBG(CXT, mnt_debug_h(cxt, "mount: evaluating permissions"));
mnt_context_get_user_mflags(cxt, &u_flags);
if (!mnt_context_is_restricted(cxt)) {
/*
* superuser mount
*/
cxt->user_mountflags &= ~MNT_MS_OWNER;
cxt->user_mountflags &= ~MNT_MS_GROUP;
cxt->user_mountflags &= ~MNT_MS_USER;
cxt->user_mountflags &= ~MNT_MS_USERS;
} else {
/*
* user mount
*/
if (!(cxt->flags & MNT_FL_TAB_APPLIED))
{
DBG(CXT, mnt_debug_h(cxt, "perms: fstab not applied, ignore user mount"));
return -EPERM;
}
/*
* Note that MS_OWNERSECURE and MS_SECURE mount options
* are applied by mnt_optstr_get_flags() from mnt_context_merge_mflags()
*/
/*
* MS_OWNER: Allow owners to mount when fstab contains the
* owner option. Note that this should never be used in a high
* security environment, but may be useful to give people at
* the console the possibility of mounting a floppy. MS_GROUP:
* Allow members of device group to mount. (Martin Dickopp)
*/
if (u_flags & (MNT_MS_OWNER | MNT_MS_GROUP)) {
struct stat sb;
struct libmnt_cache *cache = NULL;
char *xsrc = NULL;
const char *srcpath = mnt_fs_get_srcpath(cxt->fs);
if (!srcpath) { /* Ah... source is TAG */
cache = mnt_context_get_cache(cxt);
xsrc = mnt_resolve_spec(
mnt_context_get_source(cxt),
cache);
srcpath = xsrc;
}
if (!srcpath) {
DBG(CXT, mnt_debug_h(cxt, "perms: src undefined"));
return -EPERM;
}
if (strncmp(srcpath, "/dev/", 5) == 0 &&
stat(srcpath, &sb) == 0 &&
(((u_flags & MNT_MS_OWNER) && getuid() == sb.st_uid) ||
((u_flags & MNT_MS_GROUP) && mnt_in_group(sb.st_gid))))
cxt->user_mountflags |= MNT_MS_USER;
if (!cache)
free(xsrc);
}
if (!(cxt->user_mountflags & (MNT_MS_USER | MNT_MS_USERS))) {
DBG(CXT, mnt_debug_h(cxt, "permissions evaluation ends with -EPERMS"));
return -EPERM;
}
}
return 0;
}
static int mount_main(struct libmnt_context *cxt, int argc, char **argv)
{
int rc, c;
struct libmnt_fs *fs;
char *spec = NULL, *mount_point = NULL, *opts = NULL;
static const struct option longopts[] = {
{ "fake", 0, 0, 'f' },
{ "help", 0, 0, 'h' },
{ "no-mtab", 0, 0, 'n' },
{ "read-only", 0, 0, 'r' },
{ "ro", 0, 0, 'r' },
{ "verbose", 0, 0, 'v' },
{ "version", 0, 0, 'V' },
{ "read-write", 0, 0, 'w' },
{ "rw", 0, 0, 'w' },
{ "options", 1, 0, 'o' },
{ "sloppy", 0, 0, 's' },
{ NULL, 0, 0, 0 }
};
mount_config_init(progname);
mnt_context_init_helper(cxt, MNT_ACT_MOUNT, 0);
while ((c = getopt_long(argc, argv, "fhnrVvwo:s", longopts, NULL)) != -1) {
rc = mnt_context_helper_setopt(cxt, c, optarg);
if (rc == 0) /* valid option */
continue;
if (rc < 0) /* error (probably ENOMEM) */
goto err;
/* rc==1 means unknow option */
switch (c) {
case 'V':
printf("%s: ("PACKAGE_STRING")\n", progname);
return EX_SUCCESS;
case 'h':
default:
mount_usage();
return EX_USAGE;
}
}
if (optind < argc)
spec = argv[optind++];
if (optind < argc)
mount_point = argv[optind++];
if (!mount_point) {
nfs_error(_("%s: no mount point provided"), progname);
goto err;
}
if (!spec) {
nfs_error(_("%s: no mount spec provided"), progname);
goto err;
}
if (geteuid() != 0) {
nfs_error(_("%s: not installed setuid - "
"\"user\" NFS mounts not supported."), progname);
goto err;
}
verbose = mnt_context_is_verbose(cxt);
sloppy = mnt_context_is_sloppy(cxt);
nomtab = mnt_context_is_nomtab(cxt);
if (strcmp(progname, "mount.nfs4") == 0)
mnt_context_set_fstype(cxt, "nfs4");
else
mnt_context_set_fstype(cxt, "nfs"); /* default */
rc = mnt_context_set_source(cxt, spec);
if (!rc)
mnt_context_set_target(cxt, mount_point);
if (rc) {
nfs_error(_("%s: failed to set spec or mountpoint: %s"),
progname, strerror(errno));
goto err;
}
mount_point = mnt_resolve_path(mount_point,
mnt_context_get_cache(cxt));
if (chk_mountpoint(mount_point))
goto err;
/*
* Concatenate mount options from the configuration file
*/
fs = mnt_context_get_fs(cxt);
if (fs) {
opts = mnt_fs_strdup_options(fs);
opts = mount_config_opts(spec, mount_point, opts);
mnt_fs_set_options(fs, opts);
}
rc = mnt_context_prepare_mount(cxt);
if (rc) {
nfs_error(_("%s: failed to prepare mount: %s\n"),
progname, strerror(-rc));
goto err;
}
rc = try_mount(cxt, FOREGROUND);
if (rc == EX_BG) {
printf(_("%s: backgrounding \"%s\"\n"),
progname, mnt_context_get_source(cxt));
printf(_("%s: mount options: \"%s\"\n"),
progname, opts);
fflush(stdout);
if (daemon(0, 0)) {
nfs_error(_("%s: failed to start "
"background process: %s\n"),
progname, strerror(errno));
exit(EX_FAIL);
}
rc = try_mount(cxt, BACKGROUND);
if (verbose && rc)
printf(_("%s: giving up \"%s\"\n"),
progname, mnt_context_get_source(cxt));
}
mnt_context_set_syscall_status(cxt, rc == EX_SUCCESS ? 0 : -1);
mnt_context_finalize_mount(cxt); /* mtab update */
return rc;
err:
return EX_FAIL;
}