mirror of
https://github.com/libfuse/libfuse.git
synced 2026-07-07 14:47:41 +08:00
Bernd Schubert
1d70e30b52
The ENODEV fallback logic in both lib/mount.c and util/fusermount.c
incorrectly combined two conditions, causing block devices with fsname
to be treated as if they had no fsname.
Original behavior (before commit 50fa7f0bc2):
if (mo->fsname) {
if (!mo->blkdev)
sprintf(source, "%s#%s", mo->subtype, mo->fsname);
// else: keep existing source (fsname for blkdev)
} else {
strcpy(source, type);
}
This handled three cases:
1. fsname + non-blkdev -> "subtype#fsname"
2. fsname + blkdev -> fsname (unchanged)
3. no fsname -> type
Previous patches incorrectly changed this to:
if (mo->fsname && !mo->blkdev) {
source = fuse_mnt_build_source()
} else {
source = strdup(type);
}
This only handled two cases, causing case 2 (fsname + blkdev) to be
treated as case 3 (no fsname).
This patch restores the three-way logic.
Signed-off-by: Bernd Schubert <bernd@bsbernd.com>
243 lines
10 KiB
Python
243 lines
10 KiB
Python
#!/usr/bin/env python3
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'''
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Tests that observable mount state (as exposed by /proc/self/mountinfo)
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matches the options requested at mount time.
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Existing tests check filesystem behavior (read/write/xattr/...) but
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never inspect the post-mount metadata recorded by the kernel. That
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metadata is populated differently by the legacy mount(2) path and the
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new fsopen/fsconfig/fsmount path, so an option dropped on one path can
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go undetected — the subtype regression in 5e9e16d6 is one example.
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These tests assert what /proc/self/mountinfo reports for each mount,
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so a parity bug between the two paths fails loudly.
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'''
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if __name__ == '__main__':
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import pytest
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import sys
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sys.exit(pytest.main([__file__] + sys.argv[1:]))
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import os
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import subprocess
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import pytest
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from contextlib import contextmanager
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from os.path import join as pjoin
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from util import (wait_for_mount, umount, cleanup, base_cmdline, basename,
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fuse_test_marker, parse_mountinfo)
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pytestmark = fuse_test_marker()
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@contextmanager
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def hello_mount(tmpdir, output_checker, name, options=()):
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mnt_dir = str(tmpdir)
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cmdline = base_cmdline + [pjoin(basename, 'example', name),
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'-f', mnt_dir]
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if name == 'hello_ll':
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cmdline.append('-s')
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if options:
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cmdline += ['-o', ','.join(options)]
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mp = subprocess.Popen(cmdline, stdout=output_checker.fd,
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stderr=output_checker.fd)
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try:
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wait_for_mount(mp, mnt_dir)
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yield mnt_dir
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except:
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cleanup(mp, mnt_dir)
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raise
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else:
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umount(mp, mnt_dir)
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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def test_mountinfo_baseline(tmpdir, output_checker, name):
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# libfuse's add_default_subtype() (lib/helper.c) defaults the
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# subtype to basename(argv[0]) when the caller didn't pass
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# -o fsname=/-o subtype=, so the bare-mount fstype is
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# 'fuse.<example-name>', not 'fuse'. The override case is what
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# test_mountinfo_subtype below verifies; here we just assert the
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# fuse-ness and the standard kernel-side identity options.
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with hello_mount(tmpdir, output_checker, name) as mnt:
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info = parse_mountinfo(mnt)
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assert info is not None, 'mountpoint not found in /proc/self/mountinfo'
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assert info['fstype'] in ('fuse', 'fuse.' + name), \
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'unexpected fstype %r (expected fuse or fuse.%s)' % \
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(info['fstype'], name)
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assert any(o.startswith('user_id=') for o in info['super_options'])
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assert any(o.startswith('group_id=') for o in info['super_options'])
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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def test_mountinfo_subtype(tmpdir, output_checker, name):
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# Regression guard for 5e9e16d6: the new mount API needs an
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# explicit fsconfig(SET_STRING,"subtype",...). Without it the
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# kernel records fstype=='fuse' (or whatever basename default
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# leaks through) instead of the user-requested 'fuse.<subtype>'.
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# An explicit -o subtype= must override the basename default.
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with hello_mount(tmpdir, output_checker, name,
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('subtype=mysub',)) as mnt:
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info = parse_mountinfo(mnt)
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assert info is not None
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assert info['fstype'] == 'fuse.mysub', \
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'explicit subtype not propagated: fstype=%r' % info['fstype']
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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def test_mountinfo_fsname(tmpdir, output_checker, name):
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with hello_mount(tmpdir, output_checker, name,
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('fsname=myfsname',)) as mnt:
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info = parse_mountinfo(mnt)
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assert info is not None
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assert info['source'] == 'myfsname', \
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'fsname not propagated: source=%r' % info['source']
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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def test_mountinfo_subtype_fsname(tmpdir, output_checker, name):
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with hello_mount(tmpdir, output_checker, name,
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('subtype=mysub', 'fsname=myfsname')) as mnt:
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info = parse_mountinfo(mnt)
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assert info is not None
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assert info['fstype'] == 'fuse.mysub'
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# 'mysub#myfsname' is the ENODEV-fallback form when the kernel
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# rejects fuse.<subtype>; accept either so the test isn't fragile.
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assert info['source'] in ('myfsname', 'mysub#myfsname'), \
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'unexpected source: %r' % info['source']
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# (label, options, must-be-in mount_options, must-NOT-be-in mount_options)
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#
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# Library defaults are MS_NOSUID|MS_NODEV (lib/mount.c,
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# util/fusermount.c), so a no-options mount is expected to land
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# with both attrs set. The negation forms (suid/dev) clear the default
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# flags via lib/mount.c:set_mount_flag(), which on the new mount API
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# path means MOUNT_ATTR_NOSUID/MOUNT_ATTR_NODEV are not set in the
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# fsmount() call. Asserting their absence catches a routing bug where
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# the negation wasn't honored.
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ATTR_CASES = [
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('default', (), ('rw', 'nosuid', 'nodev'), ('ro',)),
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('ro', ('ro',), ('ro',), ('rw',)),
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('nosuid', ('nosuid',), ('nosuid',), ()),
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('nodev', ('nodev',), ('nodev',), ()),
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]
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# suid/dev are root-only: the kernel rejects MS_NOSUID/MS_NODEV being
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# cleared for unprivileged mounts, and fusermount3 hard-codes them on
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# anyway (util/fusermount.c:988).
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ATTR_CASES_ROOT = [
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('suid', ('suid',), (), ('nosuid',)),
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('dev', ('dev',), (), ('nodev',)),
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]
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def _check_attrs(info, must_have, must_not_have):
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assert info is not None
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for opt in must_have:
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assert opt in info['mount_options'], \
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'%r missing from mount_options=%r' % (opt, info['mount_options'])
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for opt in must_not_have:
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assert opt not in info['mount_options'], \
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'unexpected %r in mount_options=%r' % (opt, info['mount_options'])
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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@pytest.mark.parametrize('label,opts,must_have,must_not_have', ATTR_CASES,
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ids=[c[0] for c in ATTR_CASES])
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def test_mountinfo_attrs(tmpdir, output_checker, name,
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label, opts, must_have, must_not_have):
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with hello_mount(tmpdir, output_checker, name, opts) as mnt:
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info = parse_mountinfo(mnt)
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_check_attrs(info, must_have, must_not_have)
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# ro/rw also surface in super_options; if we asked for ro the
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# superblock must agree. Catches a path that sets MOUNT_ATTR_RDONLY
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# but forgets the FSCONFIG-side MS_RDONLY (or vice versa).
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if 'ro' in must_have:
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assert 'ro' in info['super_options'], \
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'ro on mount but rw on superblock: super_options=%r' % \
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info['super_options']
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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@pytest.mark.parametrize('label,opts,must_have,must_not_have',
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ATTR_CASES_ROOT,
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ids=[c[0] for c in ATTR_CASES_ROOT])
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def test_mountinfo_attrs_root(tmpdir, output_checker, name,
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label, opts, must_have, must_not_have):
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if os.getuid() != 0:
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pytest.skip('clearing nosuid/nodev requires root')
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with hello_mount(tmpdir, output_checker, name, opts) as mnt:
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info = parse_mountinfo(mnt)
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_check_attrs(info, must_have, must_not_have)
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@pytest.mark.parametrize('name', ('hello', 'hello_ll'))
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def test_mountinfo_blkdev_with_fsname(tmpdir, output_checker, name):
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"""
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Test block device mount with fsname and subtype.
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This test validates the ENODEV fallback logic for block devices with fsname.
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When mounting with blkdev=1, fsname=<device>, and subtype=mysub, the mount
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source should be the device name (fsname), not the filesystem type string.
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The ENODEV fallback has three cases:
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1. fsname + non-blkdev -> "subtype#fsname" (legacy format for regular FUSE)
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2. fsname + blkdev -> fsname only (THIS TEST - for block devices)
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3. no fsname -> type string
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This test catches a regression where the logic was incorrectly simplified
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from nested conditionals to a single combined condition (fsname && !blkdev),
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causing case 2 to fall through to case 3 and use 'fuseblk' instead of the
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device name.
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Requires root to create loop devices; skipped otherwise.
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"""
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if os.getuid() != 0:
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pytest.skip('blkdev option requires root')
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import tempfile
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# Create a file to use as a loop device
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with tempfile.NamedTemporaryFile(mode='wb', delete=False,
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dir=str(tmpdir)) as f:
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loop_file = f.name
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# Create a 1MB file
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f.write(b'\0' * (1024 * 1024))
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try:
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# Create loop device from file
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result = subprocess.run(['losetup', '-f', '--show', loop_file],
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capture_output=True, text=True, check=True)
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loop_dev = result.stdout.strip()
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try:
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# Mount with blkdev, fsname, and subtype
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# The fsname should be the loop device
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with hello_mount(tmpdir.mkdir('mnt'), output_checker, name,
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('blkdev', f'fsname={loop_dev}', 'subtype=mysub')) as mnt:
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info = parse_mountinfo(mnt)
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assert info is not None, 'mountpoint not found in /proc/self/mountinfo'
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# For block devices, fstype should be 'fuseblk' or 'fuseblk.mysub'
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# depending on whether the kernel supports the subtype
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assert info['fstype'] in ('fuseblk', 'fuseblk.mysub'), \
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f"unexpected fstype for blkdev: {info['fstype']}"
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# CRITICAL: Source should be the loop device name (fsname), NOT 'fuseblk'
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# This is what the fix ensures - before the fix, it would be 'fuseblk'
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# because the incorrect condition treated (fsname && blkdev) as (no fsname)
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assert info['source'] == loop_dev, \
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f"blkdev source should be fsname ({loop_dev}), got {info['source']}"
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finally:
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# Detach loop device
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subprocess.run(['losetup', '-d', loop_dev], check=False)
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finally:
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# Clean up file
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try:
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os.unlink(loop_file)
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except OSError:
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# Ignore cleanup errors - file may already be deleted or inaccessible
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pass
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