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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Linus Torvalds](/assets/img/avatar_default.png)
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Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf
https://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
1d7b902e28
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
991 lines
23 KiB
C
991 lines
23 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2011 Novell Inc.
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* Copyright (C) 2016 Red Hat, Inc.
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*/
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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#include <linux/xattr.h>
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#include <linux/exportfs.h>
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#include <linux/uuid.h>
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#include <linux/namei.h>
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#include <linux/ratelimit.h>
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#include "overlayfs.h"
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int ovl_want_write(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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return mnt_want_write(ovl_upper_mnt(ofs));
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}
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void ovl_drop_write(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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mnt_drop_write(ovl_upper_mnt(ofs));
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}
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struct dentry *ovl_workdir(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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return ofs->workdir;
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}
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const struct cred *ovl_override_creds(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return override_creds(ofs->creator_cred);
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}
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/*
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* Check if underlying fs supports file handles and try to determine encoding
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* type, in order to deduce maximum inode number used by fs.
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*
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* Return 0 if file handles are not supported.
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* Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
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* Return -1 if fs uses a non default encoding with unknown inode size.
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*/
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int ovl_can_decode_fh(struct super_block *sb)
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{
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if (!capable(CAP_DAC_READ_SEARCH))
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return 0;
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if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry)
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return 0;
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return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
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}
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struct dentry *ovl_indexdir(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->indexdir;
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}
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/* Index all files on copy up. For now only enabled for NFS export */
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bool ovl_index_all(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->config.nfs_export && ofs->config.index;
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}
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/* Verify lower origin on lookup. For now only enabled for NFS export */
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bool ovl_verify_lower(struct super_block *sb)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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return ofs->config.nfs_export && ofs->config.index;
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}
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struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
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{
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size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
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struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
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if (oe)
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oe->numlower = numlower;
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return oe;
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}
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bool ovl_dentry_remote(struct dentry *dentry)
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{
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return dentry->d_flags &
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(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
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}
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void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
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unsigned int mask)
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{
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struct ovl_entry *oe = OVL_E(dentry);
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unsigned int i, flags = 0;
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if (upperdentry)
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flags |= upperdentry->d_flags;
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for (i = 0; i < oe->numlower; i++)
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flags |= oe->lowerstack[i].dentry->d_flags;
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spin_lock(&dentry->d_lock);
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dentry->d_flags &= ~mask;
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dentry->d_flags |= flags & mask;
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spin_unlock(&dentry->d_lock);
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}
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bool ovl_dentry_weird(struct dentry *dentry)
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{
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return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
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DCACHE_MANAGE_TRANSIT |
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DCACHE_OP_HASH |
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DCACHE_OP_COMPARE);
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}
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enum ovl_path_type ovl_path_type(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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enum ovl_path_type type = 0;
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if (ovl_dentry_upper(dentry)) {
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type = __OVL_PATH_UPPER;
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/*
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* Non-dir dentry can hold lower dentry of its copy up origin.
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*/
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if (oe->numlower) {
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if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
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type |= __OVL_PATH_ORIGIN;
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if (d_is_dir(dentry) ||
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!ovl_has_upperdata(d_inode(dentry)))
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type |= __OVL_PATH_MERGE;
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}
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} else {
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if (oe->numlower > 1)
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type |= __OVL_PATH_MERGE;
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}
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return type;
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}
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void ovl_path_upper(struct dentry *dentry, struct path *path)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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path->mnt = ovl_upper_mnt(ofs);
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path->dentry = ovl_dentry_upper(dentry);
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}
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void ovl_path_lower(struct dentry *dentry, struct path *path)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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if (oe->numlower) {
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path->mnt = oe->lowerstack[0].layer->mnt;
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path->dentry = oe->lowerstack[0].dentry;
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} else {
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*path = (struct path) { };
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}
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}
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void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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if (oe->numlower) {
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path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
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path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
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} else {
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*path = (struct path) { };
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}
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}
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enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
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{
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enum ovl_path_type type = ovl_path_type(dentry);
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if (!OVL_TYPE_UPPER(type))
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ovl_path_lower(dentry, path);
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else
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ovl_path_upper(dentry, path);
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return type;
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}
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struct dentry *ovl_dentry_upper(struct dentry *dentry)
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{
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return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
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}
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struct dentry *ovl_dentry_lower(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[0].dentry : NULL;
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}
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const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[0].layer : NULL;
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}
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/*
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* ovl_dentry_lower() could return either a data dentry or metacopy dentry
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* dependig on what is stored in lowerstack[0]. At times we need to find
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* lower dentry which has data (and not metacopy dentry). This helper
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* returns the lower data dentry.
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*/
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struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
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}
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struct dentry *ovl_dentry_real(struct dentry *dentry)
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{
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return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
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}
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struct dentry *ovl_i_dentry_upper(struct inode *inode)
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{
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return ovl_upperdentry_dereference(OVL_I(inode));
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}
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struct inode *ovl_inode_upper(struct inode *inode)
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{
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struct dentry *upperdentry = ovl_i_dentry_upper(inode);
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return upperdentry ? d_inode(upperdentry) : NULL;
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}
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struct inode *ovl_inode_lower(struct inode *inode)
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{
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return OVL_I(inode)->lower;
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}
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struct inode *ovl_inode_real(struct inode *inode)
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{
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return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
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}
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/* Return inode which contains lower data. Do not return metacopy */
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struct inode *ovl_inode_lowerdata(struct inode *inode)
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{
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if (WARN_ON(!S_ISREG(inode->i_mode)))
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return NULL;
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return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
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}
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/* Return real inode which contains data. Does not return metacopy inode */
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struct inode *ovl_inode_realdata(struct inode *inode)
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{
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struct inode *upperinode;
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upperinode = ovl_inode_upper(inode);
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if (upperinode && ovl_has_upperdata(inode))
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return upperinode;
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return ovl_inode_lowerdata(inode);
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}
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struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
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{
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return OVL_I(inode)->cache;
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}
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void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
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{
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OVL_I(inode)->cache = cache;
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}
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void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
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{
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set_bit(flag, &OVL_E(dentry)->flags);
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}
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void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
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{
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clear_bit(flag, &OVL_E(dentry)->flags);
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}
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|
|
bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
|
|
{
|
|
return test_bit(flag, &OVL_E(dentry)->flags);
|
|
}
|
|
|
|
bool ovl_dentry_is_opaque(struct dentry *dentry)
|
|
{
|
|
return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry);
|
|
}
|
|
|
|
bool ovl_dentry_is_whiteout(struct dentry *dentry)
|
|
{
|
|
return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
|
|
}
|
|
|
|
void ovl_dentry_set_opaque(struct dentry *dentry)
|
|
{
|
|
ovl_dentry_set_flag(OVL_E_OPAQUE, dentry);
|
|
}
|
|
|
|
/*
|
|
* For hard links and decoded file handles, it's possible for ovl_dentry_upper()
|
|
* to return positive, while there's no actual upper alias for the inode.
|
|
* Copy up code needs to know about the existence of the upper alias, so it
|
|
* can't use ovl_dentry_upper().
|
|
*/
|
|
bool ovl_dentry_has_upper_alias(struct dentry *dentry)
|
|
{
|
|
return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry);
|
|
}
|
|
|
|
void ovl_dentry_set_upper_alias(struct dentry *dentry)
|
|
{
|
|
ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
|
|
}
|
|
|
|
static bool ovl_should_check_upperdata(struct inode *inode)
|
|
{
|
|
if (!S_ISREG(inode->i_mode))
|
|
return false;
|
|
|
|
if (!ovl_inode_lower(inode))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
bool ovl_has_upperdata(struct inode *inode)
|
|
{
|
|
if (!ovl_should_check_upperdata(inode))
|
|
return true;
|
|
|
|
if (!ovl_test_flag(OVL_UPPERDATA, inode))
|
|
return false;
|
|
/*
|
|
* Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
|
|
* ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
|
|
* if setting of OVL_UPPERDATA is visible, then effects of writes
|
|
* before that are visible too.
|
|
*/
|
|
smp_rmb();
|
|
return true;
|
|
}
|
|
|
|
void ovl_set_upperdata(struct inode *inode)
|
|
{
|
|
/*
|
|
* Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
|
|
* if OVL_UPPERDATA flag is visible, then effects of write operations
|
|
* before it are visible as well.
|
|
*/
|
|
smp_wmb();
|
|
ovl_set_flag(OVL_UPPERDATA, inode);
|
|
}
|
|
|
|
/* Caller should hold ovl_inode->lock */
|
|
bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
|
|
{
|
|
if (!ovl_open_flags_need_copy_up(flags))
|
|
return false;
|
|
|
|
return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
|
|
}
|
|
|
|
bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
|
|
{
|
|
if (!ovl_open_flags_need_copy_up(flags))
|
|
return false;
|
|
|
|
return !ovl_has_upperdata(d_inode(dentry));
|
|
}
|
|
|
|
bool ovl_redirect_dir(struct super_block *sb)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
|
|
return ofs->config.redirect_dir && !ofs->noxattr;
|
|
}
|
|
|
|
const char *ovl_dentry_get_redirect(struct dentry *dentry)
|
|
{
|
|
return OVL_I(d_inode(dentry))->redirect;
|
|
}
|
|
|
|
void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
|
|
{
|
|
struct ovl_inode *oi = OVL_I(d_inode(dentry));
|
|
|
|
kfree(oi->redirect);
|
|
oi->redirect = redirect;
|
|
}
|
|
|
|
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
|
|
{
|
|
struct inode *upperinode = d_inode(upperdentry);
|
|
|
|
WARN_ON(OVL_I(inode)->__upperdentry);
|
|
|
|
/*
|
|
* Make sure upperdentry is consistent before making it visible
|
|
*/
|
|
smp_wmb();
|
|
OVL_I(inode)->__upperdentry = upperdentry;
|
|
if (inode_unhashed(inode)) {
|
|
inode->i_private = upperinode;
|
|
__insert_inode_hash(inode, (unsigned long) upperinode);
|
|
}
|
|
}
|
|
|
|
static void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
WARN_ON(!inode_is_locked(inode));
|
|
/*
|
|
* Version is used by readdir code to keep cache consistent. For merge
|
|
* dirs all changes need to be noted. For non-merge dirs, cache only
|
|
* contains impure (ones which have been copied up and have origins)
|
|
* entries, so only need to note changes to impure entries.
|
|
*/
|
|
if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity)
|
|
OVL_I(inode)->version++;
|
|
}
|
|
|
|
void ovl_dir_modified(struct dentry *dentry, bool impurity)
|
|
{
|
|
/* Copy mtime/ctime */
|
|
ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));
|
|
|
|
ovl_dentry_version_inc(dentry, impurity);
|
|
}
|
|
|
|
u64 ovl_dentry_version_get(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
WARN_ON(!inode_is_locked(inode));
|
|
return OVL_I(inode)->version;
|
|
}
|
|
|
|
bool ovl_is_whiteout(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = dentry->d_inode;
|
|
|
|
return inode && IS_WHITEOUT(inode);
|
|
}
|
|
|
|
struct file *ovl_path_open(struct path *path, int flags)
|
|
{
|
|
struct inode *inode = d_inode(path->dentry);
|
|
int err, acc_mode;
|
|
|
|
if (flags & ~(O_ACCMODE | O_LARGEFILE))
|
|
BUG();
|
|
|
|
switch (flags & O_ACCMODE) {
|
|
case O_RDONLY:
|
|
acc_mode = MAY_READ;
|
|
break;
|
|
case O_WRONLY:
|
|
acc_mode = MAY_WRITE;
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
err = inode_permission(&init_user_ns, inode, acc_mode | MAY_OPEN);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
/* O_NOATIME is an optimization, don't fail if not permitted */
|
|
if (inode_owner_or_capable(&init_user_ns, inode))
|
|
flags |= O_NOATIME;
|
|
|
|
return dentry_open(path, flags, current_cred());
|
|
}
|
|
|
|
/* Caller should hold ovl_inode->lock */
|
|
static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
|
|
{
|
|
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
|
|
|
|
if (ovl_dentry_upper(dentry) &&
|
|
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
|
|
!ovl_dentry_needs_data_copy_up_locked(dentry, flags))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool ovl_already_copied_up(struct dentry *dentry, int flags)
|
|
{
|
|
bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
|
|
|
|
/*
|
|
* Check if copy-up has happened as well as for upper alias (in
|
|
* case of hard links) is there.
|
|
*
|
|
* Both checks are lockless:
|
|
* - false negatives: will recheck under oi->lock
|
|
* - false positives:
|
|
* + ovl_dentry_upper() uses memory barriers to ensure the
|
|
* upper dentry is up-to-date
|
|
* + ovl_dentry_has_upper_alias() relies on locking of
|
|
* upper parent i_rwsem to prevent reordering copy-up
|
|
* with rename.
|
|
*/
|
|
if (ovl_dentry_upper(dentry) &&
|
|
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
|
|
!ovl_dentry_needs_data_copy_up(dentry, flags))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
int ovl_copy_up_start(struct dentry *dentry, int flags)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
int err;
|
|
|
|
err = ovl_inode_lock_interruptible(inode);
|
|
if (!err && ovl_already_copied_up_locked(dentry, flags)) {
|
|
err = 1; /* Already copied up */
|
|
ovl_inode_unlock(inode);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
void ovl_copy_up_end(struct dentry *dentry)
|
|
{
|
|
ovl_inode_unlock(d_inode(dentry));
|
|
}
|
|
|
|
bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry)
|
|
{
|
|
int res;
|
|
|
|
res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_ORIGIN, NULL, 0);
|
|
|
|
/* Zero size value means "copied up but origin unknown" */
|
|
if (res >= 0)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
|
|
enum ovl_xattr ox)
|
|
{
|
|
int res;
|
|
char val;
|
|
|
|
if (!d_is_dir(dentry))
|
|
return false;
|
|
|
|
res = ovl_do_getxattr(OVL_FS(sb), dentry, ox, &val, 1);
|
|
if (res == 1 && val == 'y')
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
#define OVL_XATTR_OPAQUE_POSTFIX "opaque"
|
|
#define OVL_XATTR_REDIRECT_POSTFIX "redirect"
|
|
#define OVL_XATTR_ORIGIN_POSTFIX "origin"
|
|
#define OVL_XATTR_IMPURE_POSTFIX "impure"
|
|
#define OVL_XATTR_NLINK_POSTFIX "nlink"
|
|
#define OVL_XATTR_UPPER_POSTFIX "upper"
|
|
#define OVL_XATTR_METACOPY_POSTFIX "metacopy"
|
|
|
|
#define OVL_XATTR_TAB_ENTRY(x) \
|
|
[x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
|
|
[true] = OVL_XATTR_USER_PREFIX x ## _POSTFIX }
|
|
|
|
const char *const ovl_xattr_table[][2] = {
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
|
|
OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
|
|
};
|
|
|
|
int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
|
|
enum ovl_xattr ox, const void *value, size_t size,
|
|
int xerr)
|
|
{
|
|
int err;
|
|
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
|
|
|
if (ofs->noxattr)
|
|
return xerr;
|
|
|
|
err = ovl_do_setxattr(ofs, upperdentry, ox, value, size);
|
|
|
|
if (err == -EOPNOTSUPP) {
|
|
pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
|
|
ofs->noxattr = true;
|
|
return xerr;
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
|
|
{
|
|
int err;
|
|
|
|
if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
|
|
return 0;
|
|
|
|
/*
|
|
* Do not fail when upper doesn't support xattrs.
|
|
* Upper inodes won't have origin nor redirect xattr anyway.
|
|
*/
|
|
err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE,
|
|
"y", 1, 0);
|
|
if (!err)
|
|
ovl_set_flag(OVL_IMPURE, d_inode(dentry));
|
|
|
|
return err;
|
|
}
|
|
|
|
void ovl_set_flag(unsigned long flag, struct inode *inode)
|
|
{
|
|
set_bit(flag, &OVL_I(inode)->flags);
|
|
}
|
|
|
|
void ovl_clear_flag(unsigned long flag, struct inode *inode)
|
|
{
|
|
clear_bit(flag, &OVL_I(inode)->flags);
|
|
}
|
|
|
|
bool ovl_test_flag(unsigned long flag, struct inode *inode)
|
|
{
|
|
return test_bit(flag, &OVL_I(inode)->flags);
|
|
}
|
|
|
|
/**
|
|
* Caller must hold a reference to inode to prevent it from being freed while
|
|
* it is marked inuse.
|
|
*/
|
|
bool ovl_inuse_trylock(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
bool locked = false;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
if (!(inode->i_state & I_OVL_INUSE)) {
|
|
inode->i_state |= I_OVL_INUSE;
|
|
locked = true;
|
|
}
|
|
spin_unlock(&inode->i_lock);
|
|
|
|
return locked;
|
|
}
|
|
|
|
void ovl_inuse_unlock(struct dentry *dentry)
|
|
{
|
|
if (dentry) {
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
spin_lock(&inode->i_lock);
|
|
WARN_ON(!(inode->i_state & I_OVL_INUSE));
|
|
inode->i_state &= ~I_OVL_INUSE;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
}
|
|
|
|
bool ovl_is_inuse(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
bool inuse;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
inuse = (inode->i_state & I_OVL_INUSE);
|
|
spin_unlock(&inode->i_lock);
|
|
|
|
return inuse;
|
|
}
|
|
|
|
/*
|
|
* Does this overlay dentry need to be indexed on copy up?
|
|
*/
|
|
bool ovl_need_index(struct dentry *dentry)
|
|
{
|
|
struct dentry *lower = ovl_dentry_lower(dentry);
|
|
|
|
if (!lower || !ovl_indexdir(dentry->d_sb))
|
|
return false;
|
|
|
|
/* Index all files for NFS export and consistency verification */
|
|
if (ovl_index_all(dentry->d_sb))
|
|
return true;
|
|
|
|
/* Index only lower hardlinks on copy up */
|
|
if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* Caller must hold OVL_I(inode)->lock */
|
|
static void ovl_cleanup_index(struct dentry *dentry)
|
|
{
|
|
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
|
|
struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
|
|
struct inode *dir = indexdir->d_inode;
|
|
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
|
|
struct dentry *upperdentry = ovl_dentry_upper(dentry);
|
|
struct dentry *index = NULL;
|
|
struct inode *inode;
|
|
struct qstr name = { };
|
|
int err;
|
|
|
|
err = ovl_get_index_name(ofs, lowerdentry, &name);
|
|
if (err)
|
|
goto fail;
|
|
|
|
inode = d_inode(upperdentry);
|
|
if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
|
|
pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
|
|
upperdentry, inode->i_ino, inode->i_nlink);
|
|
/*
|
|
* We either have a bug with persistent union nlink or a lower
|
|
* hardlink was added while overlay is mounted. Adding a lower
|
|
* hardlink and then unlinking all overlay hardlinks would drop
|
|
* overlay nlink to zero before all upper inodes are unlinked.
|
|
* As a safety measure, when that situation is detected, set
|
|
* the overlay nlink to the index inode nlink minus one for the
|
|
* index entry itself.
|
|
*/
|
|
set_nlink(d_inode(dentry), inode->i_nlink - 1);
|
|
ovl_set_nlink_upper(dentry);
|
|
goto out;
|
|
}
|
|
|
|
inode_lock_nested(dir, I_MUTEX_PARENT);
|
|
index = lookup_one_len(name.name, indexdir, name.len);
|
|
err = PTR_ERR(index);
|
|
if (IS_ERR(index)) {
|
|
index = NULL;
|
|
} else if (ovl_index_all(dentry->d_sb)) {
|
|
/* Whiteout orphan index to block future open by handle */
|
|
err = ovl_cleanup_and_whiteout(OVL_FS(dentry->d_sb),
|
|
dir, index);
|
|
} else {
|
|
/* Cleanup orphan index entries */
|
|
err = ovl_cleanup(dir, index);
|
|
}
|
|
|
|
inode_unlock(dir);
|
|
if (err)
|
|
goto fail;
|
|
|
|
out:
|
|
kfree(name.name);
|
|
dput(index);
|
|
return;
|
|
|
|
fail:
|
|
pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Operations that change overlay inode and upper inode nlink need to be
|
|
* synchronized with copy up for persistent nlink accounting.
|
|
*/
|
|
int ovl_nlink_start(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
const struct cred *old_cred;
|
|
int err;
|
|
|
|
if (WARN_ON(!inode))
|
|
return -ENOENT;
|
|
|
|
/*
|
|
* With inodes index is enabled, we store the union overlay nlink
|
|
* in an xattr on the index inode. When whiting out an indexed lower,
|
|
* we need to decrement the overlay persistent nlink, but before the
|
|
* first copy up, we have no upper index inode to store the xattr.
|
|
*
|
|
* As a workaround, before whiteout/rename over an indexed lower,
|
|
* copy up to create the upper index. Creating the upper index will
|
|
* initialize the overlay nlink, so it could be dropped if unlink
|
|
* or rename succeeds.
|
|
*
|
|
* TODO: implement metadata only index copy up when called with
|
|
* ovl_copy_up_flags(dentry, O_PATH).
|
|
*/
|
|
if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
|
|
err = ovl_copy_up(dentry);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = ovl_inode_lock_interruptible(inode);
|
|
if (err)
|
|
return err;
|
|
|
|
if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
|
|
goto out;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
/*
|
|
* The overlay inode nlink should be incremented/decremented IFF the
|
|
* upper operation succeeds, along with nlink change of upper inode.
|
|
* Therefore, before link/unlink/rename, we store the union nlink
|
|
* value relative to the upper inode nlink in an upper inode xattr.
|
|
*/
|
|
err = ovl_set_nlink_upper(dentry);
|
|
revert_creds(old_cred);
|
|
|
|
out:
|
|
if (err)
|
|
ovl_inode_unlock(inode);
|
|
|
|
return err;
|
|
}
|
|
|
|
void ovl_nlink_end(struct dentry *dentry)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
|
|
const struct cred *old_cred;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
ovl_cleanup_index(dentry);
|
|
revert_creds(old_cred);
|
|
}
|
|
|
|
ovl_inode_unlock(inode);
|
|
}
|
|
|
|
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
|
|
{
|
|
/* Workdir should not be the same as upperdir */
|
|
if (workdir == upperdir)
|
|
goto err;
|
|
|
|
/* Workdir should not be subdir of upperdir and vice versa */
|
|
if (lock_rename(workdir, upperdir) != NULL)
|
|
goto err_unlock;
|
|
|
|
return 0;
|
|
|
|
err_unlock:
|
|
unlock_rename(workdir, upperdir);
|
|
err:
|
|
pr_err("failed to lock workdir+upperdir\n");
|
|
return -EIO;
|
|
}
|
|
|
|
/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
|
|
int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct dentry *dentry)
|
|
{
|
|
int res;
|
|
|
|
/* Only regular files can have metacopy xattr */
|
|
if (!S_ISREG(d_inode(dentry)->i_mode))
|
|
return 0;
|
|
|
|
res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_METACOPY, NULL, 0);
|
|
if (res < 0) {
|
|
if (res == -ENODATA || res == -EOPNOTSUPP)
|
|
return 0;
|
|
/*
|
|
* getxattr on user.* may fail with EACCES in case there's no
|
|
* read permission on the inode. Not much we can do, other than
|
|
* tell the caller that this is not a metacopy inode.
|
|
*/
|
|
if (ofs->config.userxattr && res == -EACCES)
|
|
return 0;
|
|
goto out;
|
|
}
|
|
|
|
return 1;
|
|
out:
|
|
pr_warn_ratelimited("failed to get metacopy (%i)\n", res);
|
|
return res;
|
|
}
|
|
|
|
bool ovl_is_metacopy_dentry(struct dentry *dentry)
|
|
{
|
|
struct ovl_entry *oe = dentry->d_fsdata;
|
|
|
|
if (!d_is_reg(dentry))
|
|
return false;
|
|
|
|
if (ovl_dentry_upper(dentry)) {
|
|
if (!ovl_has_upperdata(d_inode(dentry)))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
return (oe->numlower > 1);
|
|
}
|
|
|
|
char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
|
|
int padding)
|
|
{
|
|
int res;
|
|
char *s, *next, *buf = NULL;
|
|
|
|
res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_REDIRECT, NULL, 0);
|
|
if (res == -ENODATA || res == -EOPNOTSUPP)
|
|
return NULL;
|
|
if (res < 0)
|
|
goto fail;
|
|
if (res == 0)
|
|
goto invalid;
|
|
|
|
buf = kzalloc(res + padding + 1, GFP_KERNEL);
|
|
if (!buf)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_REDIRECT, buf, res);
|
|
if (res < 0)
|
|
goto fail;
|
|
if (res == 0)
|
|
goto invalid;
|
|
|
|
if (buf[0] == '/') {
|
|
for (s = buf; *s++ == '/'; s = next) {
|
|
next = strchrnul(s, '/');
|
|
if (s == next)
|
|
goto invalid;
|
|
}
|
|
} else {
|
|
if (strchr(buf, '/') != NULL)
|
|
goto invalid;
|
|
}
|
|
|
|
return buf;
|
|
invalid:
|
|
pr_warn_ratelimited("invalid redirect (%s)\n", buf);
|
|
res = -EINVAL;
|
|
goto err_free;
|
|
fail:
|
|
pr_warn_ratelimited("failed to get redirect (%i)\n", res);
|
|
err_free:
|
|
kfree(buf);
|
|
return ERR_PTR(res);
|
|
}
|
|
|
|
/*
|
|
* ovl_sync_status() - Check fs sync status for volatile mounts
|
|
*
|
|
* Returns 1 if this is not a volatile mount and a real sync is required.
|
|
*
|
|
* Returns 0 if syncing can be skipped because mount is volatile, and no errors
|
|
* have occurred on the upperdir since the mount.
|
|
*
|
|
* Returns -errno if it is a volatile mount, and the error that occurred since
|
|
* the last mount. If the error code changes, it'll return the latest error
|
|
* code.
|
|
*/
|
|
|
|
int ovl_sync_status(struct ovl_fs *ofs)
|
|
{
|
|
struct vfsmount *mnt;
|
|
|
|
if (ovl_should_sync(ofs))
|
|
return 1;
|
|
|
|
mnt = ovl_upper_mnt(ofs);
|
|
if (!mnt)
|
|
return 0;
|
|
|
|
return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
|
|
}
|