/**
* 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 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;
}
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
const char *backing_file, *optstr, *loopdev = NULL;
char *val = NULL, *loopval = NULL;
size_t len;
struct loopdev_cxt lc;
int rc = 0, lo_flags = 0;
uint64_t offset = 0, sizelimit = 0;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
backing_file = mnt_fs_get_srcpath(cxt->fs);
if (!backing_file)
return -EINVAL;
DBG(LOOP, ul_debugobj(cxt, "trying to setup device for %s", backing_file));
if (cxt->mountflags & MS_RDONLY) {
DBG(LOOP, ul_debugobj(cxt, "enabling READ-ONLY flag"));
lo_flags |= LO_FLAGS_READ_ONLY;
}
optstr = mnt_fs_get_user_options(cxt->fs);
/*
* loop=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_LOOP) &&
mnt_optstr_get_option(optstr, "loop", &val, &len) == 0 && val) {
loopval = strndup(val, len);
rc = loopval ? 0 : -ENOMEM;
}
/*
* offset=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_OFFSET) &&
mnt_optstr_get_option(optstr, "offset", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &offset);
if (rc) {
DBG(LOOP, ul_debugobj(cxt, "failed to parse offset="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* sizelimit=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_SIZELIMIT) &&
mnt_optstr_get_option(optstr, "sizelimit", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &sizelimit);
if (rc) {
DBG(LOOP, ul_debugobj(cxt, "failed to parse sizelimit="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* encryption=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_ENCRYPTION) &&
mnt_optstr_get_option(optstr, "encryption", &val, &len) == 0) {
DBG(LOOP, ul_debugobj(cxt, "encryption no longer supported"));
rc = -MNT_ERR_MOUNTOPT;
}
if (rc == 0 && is_mounted_same_loopfile(cxt,
mnt_context_get_target(cxt),
backing_file, offset))
rc = -EBUSY;
if (rc)
goto done_no_deinit;
/* It is possible to mount the same file more times. If we set more
* than one loop device referring to the same file, kernel has no
* mechanism to detect it. To prevent data corruption, the same loop
* device has to be recycled.
*/
if (backing_file) {
rc = loopcxt_init(&lc, 0);
if (rc)
goto done_no_deinit;
rc = loopcxt_find_overlap(&lc, backing_file, offset, sizelimit);
switch (rc) {
case 0: /* not found */
DBG(LOOP, ul_debugobj(cxt, "not found overlaping loopdev"));
loopcxt_deinit(&lc);
break;
case 1: /* overlap */
DBG(LOOP, ul_debugobj(cxt, "overlaping %s detected",
loopcxt_get_device(&lc)));
rc = -MNT_ERR_LOOPOVERLAP;
goto done;
case 2: /* overlap -- full size and offset match (reuse) */
{
uint32_t lc_encrypt_type;
DBG(LOOP, ul_debugobj(cxt, "re-using existing loop device %s",
loopcxt_get_device(&lc)));
/* Once a loop is initialized RO, there is no
* way to change its parameters. */
if (loopcxt_is_readonly(&lc)
&& !(lo_flags & LO_FLAGS_READ_ONLY)) {
DBG(LOOP, ul_debugobj(cxt, "%s is read-only",
loopcxt_get_device(&lc)));
rc = -EROFS;
goto done;
}
/* This is no more supported, but check to be safe. */
if (loopcxt_get_encrypt_type(&lc, &lc_encrypt_type) == 0
&& lc_encrypt_type != LO_CRYPT_NONE) {
DBG(LOOP, ul_debugobj(cxt, "encryption no longer supported for device %s",
loopcxt_get_device(&lc)));
rc = -MNT_ERR_LOOPOVERLAP;
goto done;
}
rc = 0;
goto success;
}
default: /* error */
goto done;
}
}
DBG(LOOP, ul_debugobj(cxt, "not found; create a new loop device"));
rc = loopcxt_init(&lc, 0);
if (rc)
goto done_no_deinit;
if (loopval) {
rc = loopcxt_set_device(&lc, loopval);
if (rc == 0)
loopdev = loopcxt_get_device(&lc);
}
if (rc)
goto done;
/* since 2.6.37 we don't have to store backing filename to mtab
* because kernel provides the name in /sys.
*/
if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
!mnt_context_mtab_writable(cxt)) {
DBG(LOOP, ul_debugobj(cxt, "enabling AUTOCLEAR flag"));
lo_flags |= LO_FLAGS_AUTOCLEAR;
}
do {
/* found free device */
if (!loopdev) {
rc = loopcxt_find_unused(&lc);
if (rc)
goto done;
DBG(LOOP, ul_debugobj(cxt, "trying to use %s",
loopcxt_get_device(&lc)));
}
/* set device attributes
* -- note that loopcxt_find_unused() resets "lc"
*/
rc = loopcxt_set_backing_file(&lc, backing_file);
if (!rc && offset)
rc = loopcxt_set_offset(&lc, offset);
if (!rc && sizelimit)
rc = loopcxt_set_sizelimit(&lc, sizelimit);
if (!rc)
loopcxt_set_flags(&lc, lo_flags);
if (rc) {
DBG(LOOP, ul_debugobj(cxt, "failed to set loop attributes"));
goto done;
}
/* setup the device */
rc = loopcxt_setup_device(&lc);
if (!rc)
break; /* success */
if (loopdev || rc != -EBUSY) {
DBG(LOOP, ul_debugobj(cxt, "failed to setup device"));
rc = -MNT_ERR_LOOPDEV;
goto done;
}
DBG(LOOP, ul_debugobj(cxt, "device stolen...trying again"));
} while (1);
success:
if (!rc)
rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));
if (!rc) {
/* success */
cxt->flags |= MNT_FL_LOOPDEV_READY;
if ((cxt->user_mountflags & MNT_MS_LOOP) &&
loopcxt_is_autoclear(&lc)) {
/*
* autoclear flag accepted by the kernel, don't store
* the "loop=" option to mtab.
*/
DBG(LOOP, ul_debugobj(cxt, "removing unnecessary loop= from mtab"));
cxt->user_mountflags &= ~MNT_MS_LOOP;
mnt_optstr_remove_option(&cxt->fs->user_optstr, "loop");
}
if (!(cxt->mountflags & MS_RDONLY) &&
loopcxt_is_readonly(&lc))
/*
* mount planned read-write, but loopdev is read-only,
* let's fix mount options...
*/
mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY);
/* we have to keep the device open until mount(1),
* otherwise it will be auto-cleared by kernel
*/
cxt->loopdev_fd = loopcxt_get_fd(&lc);
if (cxt->loopdev_fd < 0) {
DBG(LOOP, ul_debugobj(cxt, "failed to get loopdev FD"));
rc = -errno;
} else
loopcxt_set_fd(&lc, -1, 0);
}
done:
loopcxt_deinit(&lc);
done_no_deinit:
free(loopval);
return rc;
}
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
const char *backing_file, *optstr, *loopdev = NULL;
char *val = NULL;
size_t len;
struct loopdev_cxt lc;
int rc = 0, lo_flags = 0;
uint64_t offset = 0, sizelimit = 0;
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
if (!cxt)
return -EINVAL;
backing_file = mnt_fs_get_srcpath(cxt->fs);
if (!backing_file)
return -EINVAL;
DBG(CXT, ul_debugobj(cxt, "trying to setup loopdev for %s", backing_file));
if (cxt->mountflags & MS_RDONLY) {
DBG(CXT, ul_debugobj(cxt, "enabling READ-ONLY flag"));
lo_flags |= LO_FLAGS_READ_ONLY;
}
rc = loopcxt_init(&lc, 0);
if (rc)
return rc;
ON_DBG(CXT, loopcxt_enable_debug(&lc, 1));
optstr = mnt_fs_get_user_options(cxt->fs);
/*
* loop=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_LOOP) &&
mnt_optstr_get_option(optstr, "loop", &val, &len) == 0 && val) {
val = strndup(val, len);
rc = val ? loopcxt_set_device(&lc, val) : -ENOMEM;
free(val);
if (rc == 0)
loopdev = loopcxt_get_device(&lc);
}
/*
* offset=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_OFFSET) &&
mnt_optstr_get_option(optstr, "offset", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &offset);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "failed to parse offset="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* sizelimit=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_SIZELIMIT) &&
mnt_optstr_get_option(optstr, "sizelimit", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &sizelimit);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "failed to parse sizelimit="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* encryption=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_ENCRYPTION) &&
mnt_optstr_get_option(optstr, "encryption", &val, &len) == 0) {
DBG(CXT, ul_debugobj(cxt, "encryption no longer supported"));
rc = -MNT_ERR_MOUNTOPT;
}
if (rc == 0 && is_mounted_same_loopfile(cxt,
mnt_context_get_target(cxt),
backing_file, offset))
rc = -EBUSY;
if (rc)
goto done;
/* since 2.6.37 we don't have to store backing filename to mtab
* because kernel provides the name in /sys.
*/
if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
!mnt_context_mtab_writable(cxt)) {
DBG(CXT, ul_debugobj(cxt, "enabling AUTOCLEAR flag"));
lo_flags |= LO_FLAGS_AUTOCLEAR;
}
do {
/* found free device */
if (!loopdev) {
rc = loopcxt_find_unused(&lc);
if (rc)
goto done;
DBG(CXT, ul_debugobj(cxt, "trying to use %s",
loopcxt_get_device(&lc)));
}
/* set device attributes
* -- note that loopcxt_find_unused() resets "lc"
*/
rc = loopcxt_set_backing_file(&lc, backing_file);
if (!rc && offset)
rc = loopcxt_set_offset(&lc, offset);
if (!rc && sizelimit)
rc = loopcxt_set_sizelimit(&lc, sizelimit);
if (!rc)
loopcxt_set_flags(&lc, lo_flags);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "failed to set loopdev attributes"));
goto done;
}
/* setup the device */
rc = loopcxt_setup_device(&lc);
if (!rc)
break; /* success */
if (loopdev || rc != -EBUSY) {
DBG(CXT, ul_debugobj(cxt, "failed to setup device"));
rc = -MNT_ERR_LOOPDEV;
goto done;
}
DBG(CXT, ul_debugobj(cxt, "loopdev stolen...trying again"));
} while (1);
if (!rc)
rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));
if (!rc) {
/* success */
cxt->flags |= MNT_FL_LOOPDEV_READY;
if ((cxt->user_mountflags & MNT_MS_LOOP) &&
loopcxt_is_autoclear(&lc)) {
/*
* autoclear flag accepted by the kernel, don't store
* the "loop=" option to mtab.
*/
cxt->user_mountflags &= ~MNT_MS_LOOP;
mnt_optstr_remove_option(&cxt->fs->user_optstr, "loop");
}
if (!(cxt->mountflags & MS_RDONLY) &&
loopcxt_is_readonly(&lc))
/*
* mount planned read-write, but loopdev is read-only,
* let's fix mount options...
*/
mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY);
/* we have to keep the device open until mount(1),
* otherwise it will be auto-cleared by kernel
*/
cxt->loopdev_fd = loopcxt_get_fd(&lc);
loopcxt_set_fd(&lc, -1, 0);
}
done:
loopcxt_deinit(&lc);
return rc;
}
