/**
* mnt_context_do_mount
* @cxt: context
*
* Call mount(2) or mount.type helper. Unnecessary for mnt_context_mount().
*
* Note that this function could be called only once. If you want to mount
* another source or target than you have to call mnt_reset_context().
*
* If you want to call mount(2) for the same source and target with a diffrent
* mount flags or fstype then call mnt_context_reset_status() and then try
* again mnt_context_do_mount().
*
* WARNING: non-zero return code does not mean that mount(2) syscall or
* mount.type helper wasn't successfully called.
*
* Check mnt_context_get_status() after error!
*
* Returns: 0 on success;
* >0 in case of mount(2) error (returns syscall errno),
* <0 in case of other errors.
*/
int mnt_context_do_mount(struct libmnt_context *cxt)
{
const char *type;
int res;
assert(cxt);
assert(cxt->fs);
assert(cxt->helper_exec_status == 1);
assert(cxt->syscall_status == 1);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
assert((cxt->flags & MNT_FL_PREPARED));
assert((cxt->action == MNT_ACT_MOUNT));
DBG(CXT, mnt_debug_h(cxt, "mount: do mount"));
if (!(cxt->flags & MNT_FL_MOUNTDATA))
cxt->mountdata = (char *) mnt_fs_get_fs_options(cxt->fs);
type = mnt_fs_get_fstype(cxt->fs);
if (type)
res = do_mount(cxt, NULL);
else
res = do_mount_by_pattern(cxt, cxt->fstype_pattern);
if (mnt_context_get_status(cxt)
&& !mnt_context_is_fake(cxt)
&& !cxt->helper) {
/*
* Mounted by mount(2), do some post-mount checks
*
* Kernel allows to use MS_RDONLY for bind mounts, but the
* read-only request could be silently ignored. Check it to
* avoid 'ro' in mtab and 'rw' in /proc/mounts.
*/
if ((cxt->mountflags & MS_BIND)
&& (cxt->mountflags & MS_RDONLY)
&& !mnt_is_readonly(mnt_context_get_target(cxt)))
mnt_context_set_mflags(cxt,
cxt->mountflags & ~MS_RDONLY);
/* Kernel can silently add MS_RDONLY flag when mounting file
* system that does not have write support. Check this to avoid
* 'ro' in /proc/mounts and 'rw' in mtab.
*/
if (!(cxt->mountflags & (MS_RDONLY | MS_PROPAGATION | MS_MOVE))
&& mnt_is_readonly(mnt_context_get_target(cxt)))
mnt_context_set_mflags(cxt,
cxt->mountflags | MS_RDONLY);
}
return res;
}
static int try_mount(struct libmnt_context *cxt, int bg)
{
struct libmnt_fs *fs;
const char *p;
char *src = NULL, *tgt = NULL, *type = NULL, *opts = NULL;
unsigned long flags = 0;
int fake, ret = 0;
fs = mnt_context_get_fs(cxt);
/* libmount returns read-only pointers (const char)
* so, reallocate for nfsmount() functions.
*/
if ((p = mnt_fs_get_source(fs))) /* spec */
src = strdup(p);
if ((p = mnt_fs_get_target(fs))) /* mountpoint */
tgt = strdup(p);
if ((p = mnt_fs_get_fstype(fs))) /* FS type */
type = strdup(p);
if ((p = mnt_fs_get_fs_options(fs))) /* mount options */
opts = strdup(p);
mnt_context_get_mflags(cxt, &flags); /* mount(2) flags */
fake = mnt_context_is_fake(cxt);
if (string)
ret = nfsmount_string(src, tgt, type, flags, &opts, fake, bg);
else if (strcmp(type, "nfs4") == 0)
ret = nfs4mount(src, tgt, flags, &opts, fake, bg);
else
ret = nfsmount(src, tgt, flags, &opts, fake, bg);
/* Store mount options if not called with mount --no-mtab */
if (!ret && !mnt_context_is_nomtab(cxt))
store_mount_options(fs, opts);
free(src);
free(tgt);
free(type);
free(opts);
return ret;
}
/**
* mnt_context_do_umount:
* @cxt: mount context
*
* Umount filesystem by umount(2) or fork()+exec(/sbin/umount.type).
* Unnecessary for mnt_context_umount().
*
* See also mnt_context_disable_helpers().
*
* WARNING: non-zero return code does not mean that umount(2) syscall or
* umount.type helper wasn't successfully called.
*
* Check mnt_context_get_status() after error!
*
* Returns: 0 on success;
* >0 in case of umount(2) error (returns syscall errno),
* <0 in case of other errors.
*/
int mnt_context_do_umount(struct libmnt_context *cxt)
{
int rc;
assert(cxt);
assert(cxt->fs);
assert(cxt->helper_exec_status == 1);
assert(cxt->syscall_status == 1);
assert((cxt->flags & MNT_FL_PREPARED));
assert((cxt->action == MNT_ACT_UMOUNT));
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
rc = do_umount(cxt);
if (rc)
return rc;
if (mnt_context_get_status(cxt) && !mnt_context_is_fake(cxt)) {
/*
* Umounted, do some post-umount operations
* - remove loopdev
* - refresh in-memory mtab stuff if remount rather than
* umount has been performed
*/
if (mnt_context_is_loopdel(cxt)
&& !(cxt->mountflags & MS_REMOUNT))
rc = mnt_context_delete_loopdev(cxt);
if (!mnt_context_is_nomtab(cxt)
&& mnt_context_get_status(cxt)
&& !cxt->helper
&& mnt_context_is_rdonly_umount(cxt)
&& (cxt->mountflags & MS_REMOUNT)) {
/* use "remount" instead of "umount" in /etc/mtab */
if (!rc && cxt->update && cxt->mtab_writable)
rc = mnt_update_set_fs(cxt->update,
cxt->mountflags, NULL, cxt->fs);
}
}
return rc;
}
static int do_umount(struct libmnt_context *cxt)
{
int rc = 0, flags = 0;
const char *src, *target;
char *tgtbuf = NULL;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
assert(cxt->syscall_status == 1);
if (cxt->helper)
return exec_helper(cxt);
src = mnt_fs_get_srcpath(cxt->fs);
target = mnt_fs_get_target(cxt->fs);
if (!target)
return -EINVAL;
DBG(CXT, mnt_debug_h(cxt, "do umount"));
if (cxt->restricted && !mnt_context_is_fake(cxt)) {
/*
* extra paranoia for non-root users
* -- chdir to the parent of the mountpoint and use NOFOLLOW
* flag to avoid races and symlink attacks.
*/
if (umount_nofollow_support())
flags |= UMOUNT_NOFOLLOW;
rc = mnt_chdir_to_parent(target, &tgtbuf);
if (rc)
return rc;
target = tgtbuf;
}
if (mnt_context_is_lazy(cxt))
flags |= MNT_DETACH;
else if (mnt_context_is_force(cxt))
flags |= MNT_FORCE;
DBG(CXT, mnt_debug_h(cxt, "umount(2) [target='%s', flags=0x%08x]%s",
target, flags,
mnt_context_is_fake(cxt) ? " (FAKE)" : ""));
if (mnt_context_is_fake(cxt))
rc = 0;
else {
rc = flags ? umount2(target, flags) : umount(target);
if (rc < 0)
cxt->syscall_status = -errno;
free(tgtbuf);
}
/*
* try remount read-only
*/
if (rc < 0
&& cxt->syscall_status == -EBUSY
&& mnt_context_is_rdonly_umount(cxt)
&& src) {
mnt_context_set_mflags(cxt, (cxt->mountflags |
MS_REMOUNT | MS_RDONLY));
mnt_context_enable_loopdel(cxt, FALSE);
DBG(CXT, mnt_debug_h(cxt,
"umount(2) failed [errno=%d] -- trying to remount read-only",
-cxt->syscall_status));
rc = mount(src, mnt_fs_get_target(cxt->fs), NULL,
MS_MGC_VAL | MS_REMOUNT | MS_RDONLY, NULL);
if (rc < 0) {
cxt->syscall_status = -errno;
DBG(CXT, mnt_debug_h(cxt,
"read-only re-mount(2) failed [errno=%d]",
-cxt->syscall_status));
return -cxt->syscall_status;
}
cxt->syscall_status = 0;
DBG(CXT, mnt_debug_h(cxt, "read-only re-mount(2) success"));
return 0;
}
if (rc < 0) {
DBG(CXT, mnt_debug_h(cxt, "umount(2) failed [errno=%d]",
-cxt->syscall_status));
return -cxt->syscall_status;
}
cxt->syscall_status = 0;
DBG(CXT, mnt_debug_h(cxt, "umount(2) success"));
return 0;
}
static int exec_helper(struct libmnt_context *cxt)
{
int rc;
assert(cxt);
assert(cxt->fs);
assert(cxt->helper);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
assert(cxt->helper_exec_status == 1);
if (mnt_context_is_fake(cxt)) {
DBG(CXT, ul_debugobj(cxt, "fake mode: does not execute helper"));
cxt->helper_exec_status = rc = 0;
return rc;
}
DBG_FLUSH;
switch (fork()) {
case 0:
{
const char *args[10], *type;
int i = 0;
if (setgid(getgid()) < 0)
exit(EXIT_FAILURE);
if (setuid(getuid()) < 0)
exit(EXIT_FAILURE);
type = mnt_fs_get_fstype(cxt->fs);
args[i++] = cxt->helper; /* 1 */
args[i++] = mnt_fs_get_target(cxt->fs); /* 2 */
if (mnt_context_is_nomtab(cxt))
args[i++] = "-n"; /* 3 */
if (mnt_context_is_lazy(cxt))
args[i++] = "-l"; /* 4 */
if (mnt_context_is_force(cxt))
args[i++] = "-f"; /* 5 */
if (mnt_context_is_verbose(cxt))
args[i++] = "-v"; /* 6 */
if (mnt_context_is_rdonly_umount(cxt))
args[i++] = "-r"; /* 7 */
if (type
&& strchr(type, '.')
&& !endswith(cxt->helper, type)) {
args[i++] = "-t"; /* 8 */
args[i++] = (char *) type; /* 9 */
}
args[i] = NULL; /* 10 */
for (i = 0; args[i]; i++)
DBG(CXT, ul_debugobj(cxt, "argv[%d] = \"%s\"",
i, args[i]));
DBG_FLUSH;
execv(cxt->helper, (char * const *) args);
exit(EXIT_FAILURE);
}
default:
{
int st;
wait(&st);
cxt->helper_status = WIFEXITED(st) ? WEXITSTATUS(st) : -1;
DBG(CXT, ul_debugobj(cxt, "%s executed [status=%d]",
cxt->helper, cxt->helper_status));
cxt->helper_exec_status = rc = 0;
break;
}
case -1:
cxt->helper_exec_status = rc = -errno;
DBG(CXT, ul_debugobj(cxt, "fork() failed"));
break;
}
return rc;
}
/*
* The default is to use fstype from cxt->fs, this could be overwritten by
* @try_type argument.
*
* Returns: 0 on success,
* >0 in case of mount(2) error (returns syscall errno),
* <0 in case of other errors.
*/
static int do_mount(struct libmnt_context *cxt, const char *try_type)
{
int rc = 0;
const char *src, *target, *type;
unsigned long flags;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
if (try_type && !cxt->helper) {
rc = mnt_context_prepare_helper(cxt, "mount", try_type);
if (rc)
return rc;
}
if (cxt->helper)
return exec_helper(cxt);
flags = cxt->mountflags;
src = mnt_fs_get_srcpath(cxt->fs);
target = mnt_fs_get_target(cxt->fs);
if (!target)
return -EINVAL;
if (!src) {
/* unnecessary, should be already resolved in
* mnt_context_prepare_srcpath(), but for sure... */
DBG(CXT, mnt_debug_h(cxt, "WARNING: source is NULL -- using \"none\"!"));
src = "none";
}
type = try_type ? : mnt_fs_get_fstype(cxt->fs);
if (!(flags & MS_MGC_MSK))
flags |= MS_MGC_VAL;
DBG(CXT, mnt_debug_h(cxt, "%smount(2) "
"[source=%s, target=%s, type=%s, "
" mountflags=0x%08lx, mountdata=%s]",
mnt_context_is_fake(cxt) ? "(FAKE) " : "",
src, target, type,
flags, cxt->mountdata ? "yes" : "<none>"));
if (mnt_context_is_fake(cxt))
cxt->syscall_status = 0;
else {
if (mount(src, target, type, flags, cxt->mountdata)) {
cxt->syscall_status = -errno;
DBG(CXT, mnt_debug_h(cxt, "mount(2) failed [errno=%d %m]",
-cxt->syscall_status));
return -cxt->syscall_status;
}
DBG(CXT, mnt_debug_h(cxt, "mount(2) success"));
cxt->syscall_status = 0;
}
if (try_type && cxt->update) {
struct libmnt_fs *fs = mnt_update_get_fs(cxt->update);
if (fs)
rc = mnt_fs_set_fstype(fs, try_type);
}
return rc;
}
static int exec_helper(struct libmnt_context *cxt)
{
char *o = NULL;
int rc;
assert(cxt);
assert(cxt->fs);
assert(cxt->helper);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
DBG(CXT, mnt_debug_h(cxt, "mount: executing helper %s", cxt->helper));
rc = generate_helper_optstr(cxt, &o);
if (rc)
return -EINVAL;
DBG_FLUSH;
switch (fork()) {
case 0:
{
const char *args[12], *type;
int i = 0;
if (setgid(getgid()) < 0)
exit(EXIT_FAILURE);
if (setuid(getuid()) < 0)
exit(EXIT_FAILURE);
type = mnt_fs_get_fstype(cxt->fs);
args[i++] = cxt->helper; /* 1 */
args[i++] = mnt_fs_get_srcpath(cxt->fs);/* 2 */
args[i++] = mnt_fs_get_target(cxt->fs); /* 3 */
/*
* TODO: remove the exception for "nfs", -s is documented
* for years should be usable everywhere.
*/
if (mnt_context_is_sloppy(cxt) &&
type && startswith(type, "nfs"))
args[i++] = "-s"; /* 4 */
if (mnt_context_is_fake(cxt))
args[i++] = "-f"; /* 5 */
if (mnt_context_is_nomtab(cxt))
args[i++] = "-n"; /* 6 */
if (mnt_context_is_verbose(cxt))
args[i++] = "-v"; /* 7 */
if (o) {
args[i++] = "-o"; /* 8 */
args[i++] = o; /* 9 */
}
if (type && !endswith(cxt->helper, type)) {
args[i++] = "-t"; /* 10 */
args[i++] = type; /* 11 */
}
args[i] = NULL; /* 12 */
#ifdef CONFIG_LIBMOUNT_DEBUG
for (i = 0; args[i]; i++)
DBG(CXT, mnt_debug_h(cxt, "argv[%d] = \"%s\"",
i, args[i]));
#endif
DBG_FLUSH;
execv(cxt->helper, (char * const *) args);
exit(EXIT_FAILURE);
}
default:
{
int st;
wait(&st);
cxt->helper_status = WIFEXITED(st) ? WEXITSTATUS(st) : -1;
DBG(CXT, mnt_debug_h(cxt, "%s executed [status=%d]",
cxt->helper, cxt->helper_status));
cxt->helper_exec_status = rc = 0;
break;
}
case -1:
cxt->helper_exec_status = rc = -errno;
DBG(CXT, mnt_debug_h(cxt, "fork() failed"));
break;
}
return rc;
}
