mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-03-03 18:28:01 +01:00
c84bb79f70
Pull vfs nullfs update from Christian Brauner:
"Add a completely catatonic minimal pseudo filesystem called "nullfs"
and make pivot_root() work in the initramfs.
Currently pivot_root() does not work on the real rootfs because it
cannot be unmounted. Userspace has to recursively delete initramfs
contents manually before continuing boot, using the fragile
switch_root sequence (overmount + chroot).
Add nullfs, a minimal immutable filesystem that serves as the true
root of the mount hierarchy. The mutable rootfs (tmpfs/ramfs) is
mounted on top of it. This allows userspace to simply:
chdir(new_root);
pivot_root(".", ".");
umount2(".", MNT_DETACH);
without the traditional switch_root workarounds. systemd already
handles this correctly. It tries pivot_root() first and falls back
to MS_MOVE only when that fails.
This also means rootfs mounts in unprivileged namespaces no longer
need MNT_LOCKED, since the immutable nullfs guarantees nothing can be
revealed by unmounting the covering mount.
nullfs is a single-instance filesystem (get_tree_single()) marked
SB_NOUSER | SB_I_NOEXEC | SB_I_NODEV with an immutable empty root
directory. This means sooner or later it can be used to overmount
other directories to hide their contents without any additional
protection needed.
We enable it unconditionally. If we see any real regression we'll
hide it behind a boot option.
nullfs has extensions beyond this in the future. It will serve as a
concept to support the creation of completely empty mount namespaces -
which is work coming up in the next cycle"
* tag 'vfs-7.0-rc1.nullfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: use nullfs unconditionally as the real rootfs
docs: mention nullfs
fs: add immutable rootfs
fs: add init_pivot_root()
fs: ensure that internal tmpfs mount gets mount id zero
132 lines
4.4 KiB
Makefile
132 lines
4.4 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for the Linux filesystems.
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#
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# 14 Sep 2000, Christoph Hellwig <hch@infradead.org>
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# Rewritten to use lists instead of if-statements.
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#
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obj-y := open.o read_write.o file_table.o super.o \
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char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
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ioctl.o readdir.o select.o dcache.o inode.o \
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attr.o bad_inode.o file.o filesystems.o namespace.o \
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seq_file.o xattr.o libfs.o fs-writeback.o \
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pnode.o splice.o sync.o utimes.o d_path.o \
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stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
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fs_dirent.o fs_context.o fs_parser.o fsopen.o init.o \
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kernel_read_file.o mnt_idmapping.o remap_range.o pidfs.o \
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file_attr.o fserror.o nullfs.o
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obj-$(CONFIG_BUFFER_HEAD) += buffer.o mpage.o
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obj-$(CONFIG_PROC_FS) += proc_namespace.o
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obj-$(CONFIG_LEGACY_DIRECT_IO) += direct-io.o
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obj-y += notify/
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obj-$(CONFIG_EPOLL) += eventpoll.o
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obj-y += anon_inodes.o
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obj-$(CONFIG_SIGNALFD) += signalfd.o
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obj-$(CONFIG_TIMERFD) += timerfd.o
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obj-$(CONFIG_EVENTFD) += eventfd.o
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obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
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obj-$(CONFIG_AIO) += aio.o
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obj-$(CONFIG_FS_DAX) += dax.o
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obj-$(CONFIG_FS_ENCRYPTION) += crypto/
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obj-$(CONFIG_FS_VERITY) += verity/
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obj-$(CONFIG_FILE_LOCKING) += locks.o
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obj-$(CONFIG_BINFMT_MISC) += binfmt_misc.o
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obj-$(CONFIG_BINFMT_SCRIPT) += binfmt_script.o
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obj-$(CONFIG_BINFMT_ELF) += binfmt_elf.o
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obj-$(CONFIG_COMPAT_BINFMT_ELF) += compat_binfmt_elf.o
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obj-$(CONFIG_BINFMT_ELF_FDPIC) += binfmt_elf_fdpic.o
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obj-$(CONFIG_BINFMT_FLAT) += binfmt_flat.o
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obj-$(CONFIG_FS_STACK) += backing-file.o
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obj-$(CONFIG_FS_MBCACHE) += mbcache.o
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obj-$(CONFIG_FS_POSIX_ACL) += posix_acl.o
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obj-$(CONFIG_NFS_COMMON) += nfs_common/
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obj-$(CONFIG_COREDUMP) += coredump.o
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obj-$(CONFIG_SYSCTL) += drop_caches.o sysctls.o
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obj-$(CONFIG_FHANDLE) += fhandle.o
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obj-y += iomap/
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obj-y += quota/
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obj-$(CONFIG_PROC_FS) += proc/
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obj-$(CONFIG_KERNFS) += kernfs/
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obj-$(CONFIG_SYSFS) += sysfs/
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obj-$(CONFIG_CONFIGFS_FS) += configfs/
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obj-y += devpts/
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obj-$(CONFIG_DLM) += dlm/
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# Do not add any filesystems before this line
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obj-$(CONFIG_NETFS_SUPPORT) += netfs/
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obj-$(CONFIG_EXT4_FS) += ext4/
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# We place ext4 before ext2 so that clean ext3 root fs's do NOT mount using the
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# ext2 driver, which doesn't know about journalling! Explicitly request ext2
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# by giving the rootfstype= parameter.
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obj-$(CONFIG_EXT2_FS) += ext2/
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obj-$(CONFIG_JBD2) += jbd2/
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obj-$(CONFIG_CRAMFS) += cramfs/
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obj-$(CONFIG_SQUASHFS) += squashfs/
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obj-y += ramfs/
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obj-$(CONFIG_HUGETLBFS) += hugetlbfs/
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obj-$(CONFIG_CODA_FS) += coda/
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obj-$(CONFIG_MINIX_FS) += minix/
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obj-$(CONFIG_FAT_FS) += fat/
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obj-$(CONFIG_EXFAT_FS) += exfat/
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obj-$(CONFIG_BFS_FS) += bfs/
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obj-$(CONFIG_ISO9660_FS) += isofs/
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obj-$(CONFIG_HFSPLUS_FS) += hfsplus/ # Before hfs to find wrapped HFS+
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obj-$(CONFIG_HFS_FS) += hfs/
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obj-$(CONFIG_ECRYPT_FS) += ecryptfs/
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obj-$(CONFIG_VXFS_FS) += freevxfs/
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obj-$(CONFIG_NFS_FS) += nfs/
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obj-$(CONFIG_EXPORTFS) += exportfs/
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obj-$(CONFIG_NFSD) += nfsd/
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obj-$(CONFIG_LOCKD) += lockd/
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obj-$(CONFIG_NLS) += nls/
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obj-y += unicode/
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obj-$(CONFIG_SMBFS) += smb/
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obj-$(CONFIG_HPFS_FS) += hpfs/
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obj-$(CONFIG_NTFS3_FS) += ntfs3/
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obj-$(CONFIG_UFS_FS) += ufs/
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obj-$(CONFIG_EFS_FS) += efs/
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obj-$(CONFIG_JFFS2_FS) += jffs2/
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obj-$(CONFIG_UBIFS_FS) += ubifs/
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obj-$(CONFIG_AFFS_FS) += affs/
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obj-$(CONFIG_ROMFS_FS) += romfs/
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obj-$(CONFIG_QNX4FS_FS) += qnx4/
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obj-$(CONFIG_QNX6FS_FS) += qnx6/
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obj-$(CONFIG_AUTOFS_FS) += autofs/
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obj-$(CONFIG_ADFS_FS) += adfs/
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obj-$(CONFIG_FUSE_FS) += fuse/
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obj-$(CONFIG_OVERLAY_FS) += overlayfs/
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obj-$(CONFIG_ORANGEFS_FS) += orangefs/
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obj-$(CONFIG_UDF_FS) += udf/
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obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/
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obj-$(CONFIG_OMFS_FS) += omfs/
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obj-$(CONFIG_JFS_FS) += jfs/
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obj-$(CONFIG_XFS_FS) += xfs/
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obj-$(CONFIG_9P_FS) += 9p/
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obj-$(CONFIG_AFS_FS) += afs/
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obj-$(CONFIG_NILFS2_FS) += nilfs2/
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obj-$(CONFIG_BEFS_FS) += befs/
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obj-y += hostfs/
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obj-$(CONFIG_CACHEFILES) += cachefiles/
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obj-$(CONFIG_DEBUG_FS) += debugfs/
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obj-$(CONFIG_TRACING) += tracefs/
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obj-$(CONFIG_OCFS2_FS) += ocfs2/
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obj-$(CONFIG_BTRFS_FS) += btrfs/
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obj-$(CONFIG_GFS2_FS) += gfs2/
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obj-$(CONFIG_F2FS_FS) += f2fs/
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obj-$(CONFIG_CEPH_FS) += ceph/
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obj-$(CONFIG_PSTORE) += pstore/
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obj-$(CONFIG_EFIVAR_FS) += efivarfs/
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obj-$(CONFIG_EROFS_FS) += erofs/
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obj-$(CONFIG_VBOXSF_FS) += vboxsf/
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obj-$(CONFIG_ZONEFS_FS) += zonefs/
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obj-$(CONFIG_BPF_LSM) += bpf_fs_kfuncs.o
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obj-$(CONFIG_RESCTRL_FS) += resctrl/
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