mirror of https://gitee.com/openkylin/linux.git
13 Commits
| Author | SHA1 | Message | Date |
|---|---|---|---|
Linus Torvalds
|
7d6beb71da |
idmapped-mounts-v5.12
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCYCegywAKCRCRxhvAZXjc
ouJ6AQDlf+7jCQlQdeKKoN9QDFfMzG1ooemat36EpRRTONaGuAD8D9A4sUsG4+5f
4IU5Lj9oY4DEmF8HenbWK2ZHsesL2Qg=
=yPaw
-----END PGP SIGNATURE-----
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:
|
|
|
Linus Torvalds
|
d61c6a58ae |
\n
-----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEq1nRK9aeMoq1VSgcnJ2qBz9kQNkFAmAzoWUACgkQnJ2qBz9k QNnFgQgAlng0JOzeCQvLpwweqFl0FCxYbOsZXC1xDyvfX3TiA6A6oiOR4tx3uhQN cOQmJXaiMn4oCXjD1j6WZwGfy23yx0XchaoFK9jy2IqodaB/zUjkiWYYqt0G3XIX ud35mxjLAGS12BCD0c+vHy2RMsUFl5ep+5aBHRHZJJhCcYbl7e5ctXZ3xB1Q0mgI r639gD8JhH3ICdu9W0NaMvqOrVhJFNmhSGATKL/N96+oKub2x2ycYE4L2OXegxy3 mnFf26LjA8jt7K+KfHloTvkC6D4HVnnvKFvKiIbGKafiWhAE7q57ZO6BPCMajGue 3UHIhWGmwKXRU72+nW6N+089GbcO/g== =1e+z -----END PGP SIGNATURE----- Merge tag 'lazytime_for_v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs Pull lazytime updates from Jan Kara: "Cleanups of the lazytime handling in the writeback code making rules for calling ->dirty_inode() filesystem handlers saner" * tag 'lazytime_for_v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: ext4: simplify i_state checks in __ext4_update_other_inode_time() gfs2: don't worry about I_DIRTY_TIME in gfs2_fsync() fs: improve comments for writeback_single_inode() fs: drop redundant check from __writeback_single_inode() fs: clean up __mark_inode_dirty() a bit fs: pass only I_DIRTY_INODE flags to ->dirty_inode fs: don't call ->dirty_inode for lazytime timestamp updates fat: only specify I_DIRTY_TIME when needed in fat_update_time() fs: only specify I_DIRTY_TIME when needed in generic_update_time() fs: correctly document the inode dirty flags |
|
|
Christian Brauner
|
549c729771
|
fs: make helpers idmap mount aware
Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
|
|
Eric Biggers
|
a38ed483a7 |
fs: pass only I_DIRTY_INODE flags to ->dirty_inode
->dirty_inode is now only called when I_DIRTY_INODE (I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) is set. However it may still be passed other dirty flags at the same time, provided that these other flags happened to be passed to __mark_inode_dirty() at the same time as I_DIRTY_INODE. This doesn't make sense because there is no reason for filesystems to care about these extra flags. Nor are filesystems notified about all updates to these other flags. Therefore, mask the flags before passing them to ->dirty_inode. Also properly document ->dirty_inode in vfs.rst. Link: https://lore.kernel.org/r/20210112190253.64307-7-ebiggers@kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jan Kara <jack@suse.cz> |
|
|
Liao Pingfang
|
6a2195a104 |
docs: filesystems: vfs: Correct the struct name
The struct name should be file_system_type instead of file_system_operations. Signed-off-by: Liao Pingfang <winndows@163.com> Link: https://lore.kernel.org/r/1610265599-5101-1-git-send-email-winndows@163.com Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
|
|
Julia Lawall
|
cb56ecae4c |
docs: filesystems: vfs: correct flag name
There is no flag REMAP_CAN_SHORTEN. Commit |
|
|
Julia Lawall
|
e9b2f15b85 |
docs: filesystems: vfs: correct sync_mode flag names
Change the nonexistent flag names WBC_SYNC_ALL and WBC_SYNC_NONE to WB_SYNC_ALL and WB_SYNC_NONE, respectively, as used in the code with wbc->sync_mode. Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> Link: https://lore.kernel.org/r/1595791341-13209-1-git-send-email-Julia.Lawall@inria.fr Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
|
|
Randy Dunlap
|
8286de7c99 |
Documentation: filesystems: vfs: drop doubled words
Drop the doubled words "the". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20200703214325.31036-11-rdunlap@infradead.org Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
|
|
Alexander A. Klimov
|
c69f22f25f |
Replace HTTP links with HTTPS ones: Documentation/filesystems
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200621133552.46371-1-grandmaster@al2klimov.de
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
|
|
|
Matthew Wilcox (Oracle)
|
8151b4c8be |
mm: add readahead address space operation
This replaces ->readpages with a saner interface: - Return void instead of an ignored error code. - Page cache is already populated with locked pages when ->readahead is called. - New arguments can be passed to the implementation without changing all the filesystems that use a common helper function like mpage_readahead(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Cc: Chao Yu <yuchao0@huawei.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Gao Xiang <gaoxiang25@huawei.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Junxiao Bi <junxiao.bi@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com> Cc: Miklos Szeredi <mszeredi@redhat.com> Link: http://lkml.kernel.org/r/20200414150233.24495-12-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Mauro Carvalho Chehab
|
ec23eb54fb |
docs: fs: convert docs without extension to ReST
There are 3 remaining files without an extension inside the fs docs dir. Manually convert them to ReST. In the case of the nfs/exporting.rst file, as the nfs docs aren't ported yet, I opted to convert and add a :orphan: there, with should be removed when it gets added into a nfs-specific part of the fs documentation. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
|
|
Tobin C. Harding
|
ee5dc0491c |
docs: filesystems: vfs: Render method descriptions
Currently vfs.rst does not render well into HTML the method descriptions for VFS data structures. We can improve the HTML output by putting the description string on a new line following the method name. Suggested-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Tobin C. Harding <tobin@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
|
|
Tobin C. Harding
|
af96c1e304 |
docs: filesystems: vfs: Convert vfs.txt to RST
vfs.txt is currently stale. If we convert it to RST this is a good first step in the process of getting the VFS documentation up to date. This patch does the following (all as a single patch so as not to introduce any new SPHINX build warnings) - Use '.. code-block:: c' for C code blocks and indent the code blocks. - Use double backticks for struct member descriptions. - Fix a couple of build warnings by guarding pointers (*) with double backticks .e.g ``*ptr``. - Add vfs to Documentation/filesystems/index.rst The member descriptions paragraph indentation was not touched. It is not pretty but these do not cause build warnings. These descriptions all need updating anyways so leave it as it is for now. Signed-off-by: Tobin C. Harding <tobin@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> |