Convert all callers from working on a page to working on one page
of a folio (support for working on an entire folio can come later).
Removes a lot of folio->page->folio conversions.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Most callers have a folio, and most implementations operate on a folio,
so remove the conversion from folio->page->folio to fit through this
interface.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Convert the passed page to a folio and operate on that.
Replaces four calls to compound_head() with one.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Merge tag 'vfs-6.11-rc1.fixes.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
"This contains two fixes for this merge window:
VFS:
- I noticed that it is possible for a privileged user to mount most
filesystems with a non-initial user namespace in sb->s_user_ns.
When fsopen() is called in a non-init namespace the caller's
namespace is recorded in fs_context->user_ns. If the returned file
descriptor is then passed to a process privileged in init_user_ns,
that process can call fsconfig(fd_fs, FSCONFIG_CMD_CREATE*),
creating a new superblock with sb->s_user_ns set to the namespace
of the process which called fsopen().
This is problematic as only filesystems that raise FS_USERNS_MOUNT
are known to be able to support a non-initial s_user_ns. Others may
suffer security issues, on-disk corruption or outright crash the
kernel. Prevent that by restricting such delegation to filesystems
that allow FS_USERNS_MOUNT.
Note, that this delegation requires a privileged process to
actually create the superblock so either the privileged process is
cooperaing or someone must have tricked a privileged process into
operating on a fscontext file descriptor whose origin it doesn't
know (a stupid idea).
The bug dates back to about 5 years afaict.
Misc:
- Fix hostfs parsing when the mount request comes in via the legacy
mount api.
In the legacy mount api hostfs allows to specify the host directory
mount without any key.
Restore that behavior"
* tag 'vfs-6.11-rc1.fixes.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
hostfs: fix the host directory parse when mounting.
fs: don't allow non-init s_user_ns for filesystems without FS_USERNS_MOUNT
hostfs not keep the host directory when mounting. When the host
directory is none (default), fc->source is used as the host root
directory, and this is wrong. Here we use `parse_monolithic` to
handle the old mount path for parsing the root directory. For new
mount path, The `parse_param` is used for the host directory parse.
Reported-and-tested-by: Maciej Żenczykowski <maze@google.com>
Fixes: cd140ce9f6 ("hostfs: convert hostfs to use the new mount API")
Link: https://lore.kernel.org/all/CANP3RGceNzwdb7w=vPf5=7BCid5HVQDmz1K5kC9JG42+HVAh_g@mail.gmail.com/
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20240725065130.1821964-1-lihongbo22@huawei.com
[brauner: minor fixes]
Signed-off-by: Christian Brauner <brauner@kernel.org>
- Support for preemption
- i386 Rust support
- Huge cleanup by Benjamin Berg
- UBSAN support
- Removal of dead code
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Merge tag 'uml-for-linus-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux
Pull UML updates from Richard Weinberger:
- Support for preemption
- i386 Rust support
- Huge cleanup by Benjamin Berg
- UBSAN support
- Removal of dead code
* tag 'uml-for-linus-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (41 commits)
um: vector: always reset vp->opened
um: vector: remove vp->lock
um: register power-off handler
um: line: always fill *error_out in setup_one_line()
um: remove pcap driver from documentation
um: Enable preemption in UML
um: refactor TLB update handling
um: simplify and consolidate TLB updates
um: remove force_flush_all from fork_handler
um: Do not flush MM in flush_thread
um: Delay flushing syscalls until the thread is restarted
um: remove copy_context_skas0
um: remove LDT support
um: compress memory related stub syscalls while adding them
um: Rework syscall handling
um: Add generic stub_syscall6 function
um: Create signal stack memory assignment in stub_data
um: Remove stub-data.h include from common-offsets.h
um: time-travel: fix signal blocking race/hang
um: time-travel: remove time_exit()
...
Commit e3ec0fe944 ("hostfs: Convert hostfs_read_folio() to use a
folio") simplified hostfs_read_folio(), but in the process of converting
to using folios natively also mis-used the folio_zero_tail() function
due to the very confusing API of that function.
Very arguably it's folio_zero_tail() API itself that is buggy, since it
would make more sense (and the documentation kind of implies) that the
third argument would be the pointer to the beginning of the folio
buffer.
But no, the third argument to folio_zero_tail() is where we should start
zeroing the tail (even if we already also pass in the offset separately
as the second argument).
So fix the hostfs caller, and we can leave any folio_zero_tail() sanity
cleanup for later.
Reported-and-tested-by: Maciej Żenczykowski <maze@google.com>
Fixes: e3ec0fe944 ("hostfs: Convert hostfs_read_folio() to use a folio")
Link: https://lore.kernel.org/all/CANP3RGceNzwdb7w=vPf5=7BCid5HVQDmz1K5kC9JG42+HVAh_g@mail.gmail.com/
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'vfs-6.11.mount.api' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs mount API updates from Christian Brauner:
- Add a generic helper to parse uid and gid mount options.
Currently we open-code the same logic in various filesystems which is
error prone, especially since the verification of uid and gid mount
options is a sensitive operation in the face of idmappings.
Add a generic helper and convert all filesystems over to it. Make
sure that filesystems that are mountable in unprivileged containers
verify that the specified uid and gid can be represented in the
owning namespace of the filesystem.
- Convert hostfs to the new mount api.
* tag 'vfs-6.11.mount.api' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fuse: Convert to new uid/gid option parsing helpers
fuse: verify {g,u}id mount options correctly
fat: Convert to new uid/gid option parsing helpers
fat: Convert to new mount api
fat: move debug into fat_mount_options
vboxsf: Convert to new uid/gid option parsing helpers
tracefs: Convert to new uid/gid option parsing helpers
smb: client: Convert to new uid/gid option parsing helpers
tmpfs: Convert to new uid/gid option parsing helpers
ntfs3: Convert to new uid/gid option parsing helpers
isofs: Convert to new uid/gid option parsing helpers
hugetlbfs: Convert to new uid/gid option parsing helpers
ext4: Convert to new uid/gid option parsing helpers
exfat: Convert to new uid/gid option parsing helpers
efivarfs: Convert to new uid/gid option parsing helpers
debugfs: Convert to new uid/gid option parsing helpers
autofs: Convert to new uid/gid option parsing helpers
fs_parse: add uid & gid option option parsing helpers
hostfs: Add const qualifier to host_root in hostfs_fill_super()
hostfs: convert hostfs to use the new mount API
With ARCH=um, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in fs/hostfs/hostfs.o
Add the missing invocation of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://patch.msgid.link/20240702-md-um-fs-hostfs-v1-1-fd2b565027e7@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
dev_t is a kernel type and may have different definitions
in kernel and userspace. On 32-bit x86 this currently makes
the stat structure being 4 bytes longer in the user code,
causing stack corruption.
However, this is (potentially) not the only problem, since
dev_t is a different type on user/kernel side, so we don't
know that the major/minor encoding isn't also different.
Decode/encode it instead to address both problems.
Cc: stable@vger.kernel.org
Fixes: 74ce793bcb ("hostfs: Fix ephemeral inodes")
Link: https://patch.msgid.link/20240702092440.acc960585dd5.Id0767e12f562a69c6cd3c3262dc3d765db350cf6@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
After the recent conversion to the new mount API, there is a warning
when building hostfs (which may be upgraded to an error via
CONFIG_WERROR=y):
fs/hostfs/hostfs_kern.c: In function 'hostfs_fill_super':
fs/hostfs/hostfs_kern.c:942:27: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
942 | char *host_root = fc->source;
| ^~
Add the 'const' qualifier, as host_root will not be modified after its
assignment. Move the assignment to keep the existing reverse Christmas
tree order intact.
Fixes: cd140ce9f6 ("hostfs: convert hostfs to use the new mount API")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20240611-hostfs-fix-mount-api-conversion-v1-1-ef75bbc77f44@kernel.org
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Convert the hostfs filesystem to the new internal mount API as the old
one will be obsoleted and removed. This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.
See Documentation/filesystems/mount_api.txt for more information.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20240530120111.3794664-1-lihongbo22@huawei.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Remove the use of page APIs, including setting/clearing the error flag
which is never checked on hostfs folios. This does not include support
for large folios as kmap_local_folio() maps only one page at a time.
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-um@lists.infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240530202110.2653630-8-willy@infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230705190309.579783-48-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Merge tag 'landlock-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux
Pull landlock updates from Mickaël Salaün:
"Add support for Landlock to UML.
To do this, this fixes the way hostfs manages inodes according to the
underlying filesystem [1]. They are now properly handled as for other
filesystems, which enables Landlock support (and probably other
features).
This also extends Landlock's tests with 6 pseudo filesystems,
including hostfs"
[1] https://lore.kernel.org/all/20230612191430.339153-1-mic@digikod.net/
* tag 'landlock-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
selftests/landlock: Add hostfs tests
selftests/landlock: Add tests for pseudo filesystems
selftests/landlock: Make mounts configurable
selftests/landlock: Add supports_filesystem() helper
selftests/landlock: Don't create useless file layouts
hostfs: Fix ephemeral inodes
hostfs creates a new inode for each opened or created file, which
created useless inode allocations and forbade identifying a host file
with a kernel inode.
Fix this uncommon filesystem behavior by tying kernel inodes to host
file's inode and device IDs. Even if the host filesystem inodes may be
recycled, this cannot happen while a file referencing it is opened,
which is the case with hostfs. It should be noted that hostfs inode IDs
may not be unique for the same hostfs superblock because multiple host's
(backed) superblocks may be used.
Delete inodes when dropping them to force backed host's file descriptors
closing.
This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes
Landlock fully supported by UML. This is very useful for testing
changes.
These changes also factor out and simplify some helpers thanks to the
new hostfs_inode_update() and the hostfs_iget() revamp: read_name(),
hostfs_create(), hostfs_lookup(), hostfs_mknod(), and
hostfs_fill_sb_common().
A following commit with new Landlock tests check this new hostfs inode
consistency.
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Instead of exporting the set of functions provided by
glibc that are needed for hostfs_user.c, just build that
into the kernel image whenever hostfs is built, and then
export _those_ functions cleanly, to be independent of
the libc implementation.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
- Add support for rust (yay!)
- Add support for LTO
- Add platform bus support to virtio-pci
- Various virtio fixes
- Coding style, spelling cleanups
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Merge tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux
Pull UML updates from Richard Weinberger:
- Add support for rust (yay!)
- Add support for LTO
- Add platform bus support to virtio-pci
- Various virtio fixes
- Coding style, spelling cleanups
* tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (27 commits)
Documentation: rust: Fix arch support table
uml: vector: Remove unused definitions VECTOR_{WRITE,HEADERS}
um: virt-pci: properly remove PCI device from bus
um: virtio_uml: move device breaking into workqueue
um: virtio_uml: mark device as unregistered when breaking it
um: virtio_uml: free command if adding to virtqueue failed
UML: define RUNTIME_DISCARD_EXIT
virt-pci: add platform bus support
um-virt-pci: Make max delay configurable
um: virt-pci: implement pcibios_get_phb_of_node()
um: Support LTO
um: put power options in a menu
um: Use CFLAGS_vmlinux
um: Prevent building modules incompatible with MODVERSIONS
um: Avoid pcap multiple definition errors
um: Make the definition of cpu_data more compatible
x86: um: vdso: Add '%rcx' and '%r11' to the syscall clobber list
rust: arch/um: Add support for CONFIG_RUST under x86_64 UML
rust: arch/um: Disable FP/SIMD instruction to match x86
rust: arch/um: Use 'pie' relocation mode under UML
...
- Change V=1 option to print both short log and full command log.
- Allow V=1 and V=2 to be combined as V=12.
- Make W=1 detect wrong .gitignore files.
- Tree-wide cleanups for unused command line arguments passed to Clang.
- Stop using -Qunused-arguments with Clang.
- Make scripts/setlocalversion handle only correct release tags instead
of any arbitrary annotated tag.
- Create Debian and RPM source packages without cleaning the source tree.
- Various cleanups for packaging.
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Merge tag 'kbuild-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Change V=1 option to print both short log and full command log
- Allow V=1 and V=2 to be combined as V=12
- Make W=1 detect wrong .gitignore files
- Tree-wide cleanups for unused command line arguments passed to Clang
- Stop using -Qunused-arguments with Clang
- Make scripts/setlocalversion handle only correct release tags instead
of any arbitrary annotated tag
- Create Debian and RPM source packages without cleaning the source
tree
- Various cleanups for packaging
* tag 'kbuild-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (74 commits)
kbuild: rpm-pkg: remove unneeded KERNELRELEASE from modules/headers_install
docs: kbuild: remove description of KBUILD_LDS_MODULE
.gitattributes: use 'dts' diff driver for *.dtso files
kbuild: deb-pkg: improve the usability of source package
kbuild: deb-pkg: fix binary-arch and clean in debian/rules
kbuild: tar-pkg: use tar rules in scripts/Makefile.package
kbuild: make perf-tar*-src-pkg work without relying on git
kbuild: deb-pkg: switch over to source format 3.0 (quilt)
kbuild: deb-pkg: make .orig tarball a hard link if possible
kbuild: deb-pkg: hide KDEB_SOURCENAME from Makefile
kbuild: srcrpm-pkg: create source package without cleaning
kbuild: rpm-pkg: build binary packages from source rpm
kbuild: deb-pkg: create source package without cleaning
kbuild: add a tool to list files ignored by git
Documentation/llvm: add Chimera Linux, Google and Meta datacenters
setlocalversion: use only the correct release tag for git-describe
setlocalversion: clean up the construction of version output
.gitignore: ignore *.cover and *.mbx
kbuild: remove --include-dir MAKEFLAG from top Makefile
kbuild: fix trivial typo in comment
...
I added $(srctree)/ to some included Makefiles in the following commits:
- 3204a7fb98 ("kbuild: prefix $(srctree)/ to some included Makefiles")
- d828563955 ("kbuild: do not require sub-make for separate output tree builds")
They were a preparation for removing --include-dir flag.
I have never thought --include-dir useful. Rather, it _is_ harmful.
For example, run the following commands:
$ make -s ARCH=x86 mrproper defconfig
$ make ARCH=arm O=foo dtbs
make[1]: Entering directory '/tmp/linux/foo'
HOSTCC scripts/basic/fixdep
Error: kernelrelease not valid - run 'make prepare' to update it
UPD include/config/kernel.release
make[1]: Leaving directory '/tmp/linux/foo'
The first command configures the source tree for x86. The next command
tries to build ARM device trees in the separate foo/ directory - this
must stop because the directory foo/ has not been configured yet.
However, due to --include-dir=$(abs_srctree), the top Makefile includes
the wrong include/config/auto.conf from the source tree and continues
building. Kbuild traverses the directory tree, but of course it does
not work correctly. The Error message is also pointless - 'make prepare'
does not help at all for fixing the issue.
This commit fixes more arch Makefile, and finally removes --include-dir
from the top Makefile.
There are more breakages under drivers/, but I do not volunteer to fix
them all. I just moved --include-dir to drivers/Makefile.
With this commit, the second command will stop with a sensible message.
$ make -s ARCH=x86 mrproper defconfig
$ make ARCH=arm O=foo dtbs
make[1]: Entering directory '/tmp/linux/foo'
SYNC include/config/auto.conf.cmd
***
*** The source tree is not clean, please run 'make ARCH=arm mrproper'
*** in /tmp/linux
***
make[2]: *** [../Makefile:646: outputmakefile] Error 1
/tmp/linux/Makefile:770: include/config/auto.conf.cmd: No such file or directory
make[1]: *** [/tmp/linux/Makefile:793: include/config/auto.conf.cmd] Error 2
make[1]: Leaving directory '/tmp/linux/foo'
make: *** [Makefile:226: __sub-make] Error 2
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The use of kmap() is being deprecated in favor of kmap_local_page().
There are two main problems with kmap(): (1) It comes with an overhead as
the mapping space is restricted and protected by a global lock for
synchronization and (2) it also requires global TLB invalidation when the
kmap’s pool wraps and it might block when the mapping space is fully
utilized until a slot becomes available.
With kmap_local_page() the mappings are per thread, CPU local, can take
page faults, and can be called from any context (including interrupts).
It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore,
the tasks can be preempted and, when they are scheduled to run again, the
kernel virtual addresses are restored and still valid.
Therefore, replace kmap() with kmap_local_page() in hostfs_kern.c, it
being the only file with kmap() call sites currently left in fs/hostfs.
Cc: "Venkataramanan, Anirudh" <anirudh.venkataramanan@intel.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.
Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If a page can't be written back, we need to call mapping_set_error(),
not clear the page's Uptodate flag. Also remove the clearing of PageError
on success; that flag is used for read errors, not write errors.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
This is a "weak" conversion which converts straight back to using pages.
A full conversion should be performed at some point, hopefully by
someone familiar with the filesystem.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
There are no more aop flags left, so remove the parameter.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
There are no more aop flags left, so remove the parameter.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Primarily this series converts some of the address_space operations
to take a folio instead of a page.
->is_partially_uptodate() takes a folio instead of a page and changes the
type of the 'from' and 'count' arguments to make it obvious they're bytes.
->invalidatepage() becomes ->invalidate_folio() and has a similar type change.
->launder_page() becomes ->launder_folio()
->set_page_dirty() becomes ->dirty_folio() and adds the address_space as
an argument.
There are a couple of other misc changes up front that weren't worth
separating into their own pull request.
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Merge tag 'folio-5.18b' of git://git.infradead.org/users/willy/pagecache
Pull filesystem folio updates from Matthew Wilcox:
"Primarily this series converts some of the address_space operations to
take a folio instead of a page.
Notably:
- a_ops->is_partially_uptodate() takes a folio instead of a page and
changes the type of the 'from' and 'count' arguments to make it
obvious they're bytes.
- a_ops->invalidatepage() becomes ->invalidate_folio() and has a
similar type change.
- a_ops->launder_page() becomes ->launder_folio()
- a_ops->set_page_dirty() becomes ->dirty_folio() and adds the
address_space as an argument.
There are a couple of other misc changes up front that weren't worth
separating into their own pull request"
* tag 'folio-5.18b' of git://git.infradead.org/users/willy/pagecache: (53 commits)
fs: Remove aops ->set_page_dirty
fb_defio: Use noop_dirty_folio()
fs: Convert __set_page_dirty_no_writeback to noop_dirty_folio
fs: Convert __set_page_dirty_buffers to block_dirty_folio
nilfs: Convert nilfs_set_page_dirty() to nilfs_dirty_folio()
mm: Convert swap_set_page_dirty() to swap_dirty_folio()
ubifs: Convert ubifs_set_page_dirty to ubifs_dirty_folio
f2fs: Convert f2fs_set_node_page_dirty to f2fs_dirty_node_folio
f2fs: Convert f2fs_set_data_page_dirty to f2fs_dirty_data_folio
f2fs: Convert f2fs_set_meta_page_dirty to f2fs_dirty_meta_folio
afs: Convert afs_dir_set_page_dirty() to afs_dir_dirty_folio()
btrfs: Convert extent_range_redirty_for_io() to use folios
fs: Convert trivial uses of __set_page_dirty_nobuffers to filemap_dirty_folio
btrfs: Convert from set_page_dirty to dirty_folio
fscache: Convert fscache_set_page_dirty() to fscache_dirty_folio()
fs: Add aops->dirty_folio
fs: Remove aops->launder_page
orangefs: Convert launder_page to launder_folio
nfs: Convert from launder_page to launder_folio
fuse: Convert from launder_page to launder_folio
...
The inode allocation is supposed to use alloc_inode_sb(), so convert
kmem_cache_alloc() of all filesystems to alloc_inode_sb().
Link: https://lkml.kernel.org/r/20220228122126.37293-5-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Theodore Ts'o <tytso@mit.edu> [ext4]
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These filesystems use __set_page_dirty_nobuffers() either directly or
with a very thin wrapper; convert them en masse.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs
Tested-by: David Howells <dhowells@redhat.com> # afs
Hostfs was not setting up the backing device information, which means it
uses the noop bdi. The noop bdi does not have the writeback capability
enabled, which in turns means dirty pages never got written back to
storage.
In other words programs using mmap to write to files on hostfs never
actually got their data written out...
Fix this by simply setting up the bdi with default settings as all the
required code for writeback is already in place.
Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>
Reviewed-by: Christopher Obbard <chris.obbard@collabora.com>
Tested-by: Ritesh Raj Sarraf <ritesh@collabora.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
There's really no good reason not to, and e.g. trace-cmd
currently requires it for the temporary per-CPU files.
Hook up splice_write just like everyone else does.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Pull misc vfs updates from Al Viro:
"Assorted stuff all over the place"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
useful constants: struct qstr for ".."
hostfs_open(): don't open-code file_dentry()
whack-a-mole: kill strlen_user() (again)
autofs: should_expire() argument is guaranteed to be positive
apparmor:match_mn() - constify devpath argument
buffer: a small optimization in grow_buffers
get rid of autofs_getpath()
constify dentry argument of dentry_path()/dentry_path_raw()
Pull vfs inode type handling updates from Al Viro:
"We should never change the type bits of ->i_mode or the method tables
(->i_op and ->i_fop) of a live inode.
Unfortunately, not all filesystems took care to prevent that"
* 'work.inode-type-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
spufs: fix bogosity in S_ISGID handling
9p: missing chunk of "fs/9p: Don't update file type when updating file attributes"
openpromfs: don't do unlock_new_inode() until the new inode is set up
hostfs_mknod(): don't bother with init_special_inode()
cifs: have cifs_fattr_to_inode() refuse to change type on live inode
cifs: have ->mkdir() handle race with another client sanely
do_cifs_create(): don't set ->i_mode of something we had not created
gfs2: be careful with inode refresh
ocfs2_inode_lock_update(): make sure we don't change the type bits of i_mode
orangefs_inode_is_stale(): i_mode type bits do *not* form a bitmap...
vboxsf: don't allow to change the inode type
afs: Fix updating of i_mode due to 3rd party change
ceph: don't allow type or device number to change on non-I_NEW inodes
ceph: fix up error handling with snapdirs
new helper: inode_wrong_type()
1) argument should not be freed in any case - the caller already has
it as ->s_fs_info (and uses it a lot afterwards)
2) allocate readlink buffer with kmalloc() - the caller has no way
to tell if it's got that (on absolute symlink) or a result of
kasprintf(). Sure, for SLAB and SLUB kfree() works on results of
kmem_cache_alloc(), but that's not documented anywhere, might change
in the future *and* is already not true for SLOB.
Fixes: 52b209f7b8 ("get rid of hostfs_read_inode()")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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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.pdfhttps://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
...
This collects all of them together and makes it possible to
e.g. exclude it from slub debugging.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
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>
When file attributes are changed most filesystems rely on the
setattr_prepare(), setattr_copy(), and notify_change() helpers for
initialization and permission checking. Let them handle idmapped mounts.
If the inode is accessed through an idmapped mount map it into the
mount's user namespace. Afterwards the checks are identical to
non-idmapped mounts. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.
Helpers that perform checks on the ia_uid and ia_gid fields in struct
iattr assume that ia_uid and ia_gid are intended values and have already
been mapped correctly at the userspace-kernelspace boundary as we
already do today. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-8-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>
