Commit Graph

953 Commits

Author SHA1 Message Date
Linus Torvalds 353ad6c083 integrity-v6.10
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Merge tag 'integrity-v6.10' of ssh://ra.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity updates from Mimi Zohar:
 "Two IMA changes, one EVM change, a use after free bug fix, and a code
  cleanup to address "-Wflex-array-member-not-at-end" warnings:

   - The existing IMA {ascii, binary}_runtime_measurements lists include
     a hard coded SHA1 hash. To address this limitation, define per TPM
     enabled hash algorithm {ascii, binary}_runtime_measurements lists

   - Close an IMA integrity init_module syscall measurement gap by
     defining a new critical-data record

   - Enable (partial) EVM support on stacked filesystems (overlayfs).
     Only EVM portable & immutable file signatures are copied up, since
     they do not contain filesystem specific metadata"

* tag 'integrity-v6.10' of ssh://ra.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: add crypto agility support for template-hash algorithm
  evm: Rename is_unsupported_fs to is_unsupported_hmac_fs
  fs: Rename SB_I_EVM_UNSUPPORTED to SB_I_EVM_HMAC_UNSUPPORTED
  evm: Enforce signatures on unsupported filesystem for EVM_INIT_X509
  ima: re-evaluate file integrity on file metadata change
  evm: Store and detect metadata inode attributes changes
  ima: Move file-change detection variables into new structure
  evm: Use the metadata inode to calculate metadata hash
  evm: Implement per signature type decision in security_inode_copy_up_xattr
  security: allow finer granularity in permitting copy-up of security xattrs
  ima: Rename backing_inode to real_inode
  integrity: Avoid -Wflex-array-member-not-at-end warnings
  ima: define an init_module critical data record
  ima: Fix use-after-free on a dentry's dname.name
2024-05-15 08:43:02 -07:00
Stefan Berger 1f65e57dc5 fs: Rename SB_I_EVM_UNSUPPORTED to SB_I_EVM_HMAC_UNSUPPORTED
Now that EVM supports RSA signatures for previously completely
unsupported filesystems rename the flag SB_I_EVM_UNSUPPORTED to
SB_I_EVM_HMAC_UNSUPPORTED to reflect that only HMAC is not supported.

Suggested-by: Amir Goldstein <amir73il@gmail.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2024-04-09 17:14:58 -04:00
Stefan Berger 3253804773 security: allow finer granularity in permitting copy-up of security xattrs
Copying up xattrs is solely based on the security xattr name. For finer
granularity add a dentry parameter to the security_inode_copy_up_xattr
hook definition, allowing decisions to be based on the xattr content as
well.

Co-developed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM,SELinux)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2024-04-09 17:14:57 -04:00
Luis Henriques (SUSE) 7b30851a70
fs_parser: move fsparam_string_empty() helper into header
Since both ext4 and overlayfs define the same macro to specify string
parameters that may allow empty values, define it in an header file so
that this helper can be shared.

Signed-off-by: Luis Henriques (SUSE) <luis.henriques@linux.dev>
Link: https://lore.kernel.org/r/20240312104757.27333-1-luis.henriques@linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-03-26 09:01:18 +01:00
Amir Goldstein 77a28aa476 ovl: relax WARN_ON in ovl_verify_area()
syzbot hit an assertion in copy up data loop which looks like it is
the result of a lower file whose size is being changed underneath
overlayfs.

This type of use case is documented to cause undefined behavior, so
returning EIO error for the copy up makes sense, but it should not be
causing a WARN_ON assertion.

Reported-and-tested-by: syzbot+3abd99031b42acf367ef@syzkaller.appspotmail.com
Fixes: ca7ab48240 ("ovl: add permission hooks outside of do_splice_direct()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2024-03-17 15:59:41 +02:00
Linus Torvalds f88c3fb81c mm, slab: remove last vestiges of SLAB_MEM_SPREAD
Yes, yes, I know the slab people were planning on going slow and letting
every subsystem fight this thing on their own.  But let's just rip off
the band-aid and get it over and done with.  I don't want to see a
number of unnecessary pull requests just to get rid of a flag that no
longer has any meaning.

This was mainly done with a couple of 'sed' scripts and then some manual
cleanup of the end result.

Link: https://lore.kernel.org/all/CAHk-=wji0u+OOtmAOD-5JV3SXcRJF___k_+8XNKmak0yd5vW1Q@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-03-12 20:32:19 -07:00
Linus Torvalds 0f1a876682 vfs-6.9.uuid
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Merge tag 'vfs-6.9.uuid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs uuid updates from Christian Brauner:
 "This adds two new ioctl()s for getting the filesystem uuid and
  retrieving the sysfs path based on the path of a mounted filesystem.
  Getting the filesystem uuid has been implemented in filesystem
  specific code for a while it's now lifted as a generic ioctl"

* tag 'vfs-6.9.uuid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  xfs: add support for FS_IOC_GETFSSYSFSPATH
  fs: add FS_IOC_GETFSSYSFSPATH
  fat: Hook up sb->s_uuid
  fs: FS_IOC_GETUUID
  ovl: convert to super_set_uuid()
  fs: super_set_uuid()
2024-03-11 11:02:06 -07:00
Linus Torvalds 7ea65c89d8 vfs-6.9.misc
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Merge tag 'vfs-6.9.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Misc features, cleanups, and fixes for vfs and individual filesystems.

  Features:

   - Support idmapped mounts for hugetlbfs.

   - Add RWF_NOAPPEND flag for pwritev2(). This allows us to fix a bug
     where the passed offset is ignored if the file is O_APPEND. The new
     flag allows a caller to enforce that the offset is honored to
     conform to posix even if the file was opened in append mode.

   - Move i_mmap_rwsem in struct address_space to avoid false sharing
     between i_mmap and i_mmap_rwsem.

   - Convert efs, qnx4, and coda to use the new mount api.

   - Add a generic is_dot_dotdot() helper that's used by various
     filesystems and the VFS code instead of open-coding it multiple
     times.

   - Recently we've added stable offsets which allows stable ordering
     when iterating directories exported through NFS on e.g., tmpfs
     filesystems. Originally an xarray was used for the offset map but
     that caused slab fragmentation issues over time. This switches the
     offset map to the maple tree which has a dense mode that handles
     this scenario a lot better. Includes tests.

   - Finally merge the case-insensitive improvement series Gabriel has
     been working on for a long time. This cleanly propagates case
     insensitive operations through ->s_d_op which in turn allows us to
     remove the quite ugly generic_set_encrypted_ci_d_ops() operations.
     It also improves performance by trying a case-sensitive comparison
     first and then fallback to case-insensitive lookup if that fails.
     This also fixes a bug where overlayfs would be able to be mounted
     over a case insensitive directory which would lead to all sort of
     odd behaviors.

  Cleanups:

   - Make file_dentry() a simple accessor now that ->d_real() is
     simplified because of the backing file work we did the last two
     cycles.

   - Use the dedicated file_mnt_idmap helper in ntfs3.

   - Use smp_load_acquire/store_release() in the i_size_read/write
     helpers and thus remove the hack to handle i_size reads in the
     filemap code.

   - The SLAB_MEM_SPREAD is a nop now. Remove it from various places in
     fs/

   - It's no longer necessary to perform a second built-in initramfs
     unpack call because we retain the contents of the previous
     extraction. Remove it.

   - Now that we have removed various allocators kfree_rcu() always
     works with kmem caches and kmalloc(). So simplify various places
     that only use an rcu callback in order to handle the kmem cache
     case.

   - Convert the pipe code to use a lockdep comparison function instead
     of open-coding the nesting making lockdep validation easier.

   - Move code into fs-writeback.c that was located in a header but can
     be made static as it's only used in that one file.

   - Rewrite the alignment checking iterators for iovec and bvec to be
     easier to read, and also significantly more compact in terms of
     generated code. This saves 270 bytes of text on x86-64 (with
     clang-18) and 224 bytes on arm64 (with gcc-13). In profiles it also
     saves a bit of time for the same workload.

   - Switch various places to use KMEM_CACHE instead of
     kmem_cache_create().

   - Use inode_set_ctime_to_ts() in inode_set_ctime_current()

   - Use kzalloc() in name_to_handle_at() to avoid kernel infoleak.

   - Various smaller cleanups for eventfds.

  Fixes:

   - Fix various comments and typos, and unneeded initializations.

   - Fix stack allocation hack for clang in the select code.

   - Improve dump_mapping() debug code on a best-effort basis.

   - Fix build errors in various selftests.

   - Avoid wrap-around instrumentation in various places.

   - Don't allow user namespaces without an idmapping to be used for
     idmapped mounts.

   - Fix sysv sb_read() call.

   - Fix fallback implementation of the get_name() export operation"

* tag 'vfs-6.9.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (70 commits)
  hugetlbfs: support idmapped mounts
  qnx4: convert qnx4 to use the new mount api
  fs: use inode_set_ctime_to_ts to set inode ctime to current time
  libfs: Drop generic_set_encrypted_ci_d_ops
  ubifs: Configure dentry operations at dentry-creation time
  f2fs: Configure dentry operations at dentry-creation time
  ext4: Configure dentry operations at dentry-creation time
  libfs: Add helper to choose dentry operations at mount-time
  libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops
  fscrypt: Drop d_revalidate once the key is added
  fscrypt: Drop d_revalidate for valid dentries during lookup
  fscrypt: Factor out a helper to configure the lookup dentry
  ovl: Always reject mounting over case-insensitive directories
  libfs: Attempt exact-match comparison first during casefolded lookup
  efs: remove SLAB_MEM_SPREAD flag usage
  jfs: remove SLAB_MEM_SPREAD flag usage
  minix: remove SLAB_MEM_SPREAD flag usage
  openpromfs: remove SLAB_MEM_SPREAD flag usage
  proc: remove SLAB_MEM_SPREAD flag usage
  qnx6: remove SLAB_MEM_SPREAD flag usage
  ...
2024-03-11 09:38:17 -07:00
Christian Brauner 09406ad8e5 case-insensitive updates for 6.9
- Patch case-insensitive lookup by trying the case-exact comparison
 first, before falling back to costly utf8 casefolded comparison.
 
 - Fix to forbid using a case-insensitive directory as part of an
 overlayfs mount.
 
 - Patchset to ensure d_op are set at d_alloc time for fscrypt and
 casefold volumes, ensuring filesystem dentries will all have the correct
 ops, whether they come from a lookup or not.
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Merge tag 'for-next-6.9' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/krisman/unicode into vfs.misc

Merge case-insensitive updates from Gabriel Krisman Bertazi:

- Patch case-insensitive lookup by trying the case-exact comparison
  first, before falling back to costly utf8 casefolded comparison.

- Fix to forbid using a case-insensitive directory as part of an
  overlayfs mount.

- Patchset to ensure d_op are set at d_alloc time for fscrypt and
  casefold volumes, ensuring filesystem dentries will all have the
  correct ops, whether they come from a lookup or not.

* tag 'for-next-6.9' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/krisman/unicode:
  libfs: Drop generic_set_encrypted_ci_d_ops
  ubifs: Configure dentry operations at dentry-creation time
  f2fs: Configure dentry operations at dentry-creation time
  ext4: Configure dentry operations at dentry-creation time
  libfs: Add helper to choose dentry operations at mount-time
  libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops
  fscrypt: Drop d_revalidate once the key is added
  fscrypt: Drop d_revalidate for valid dentries during lookup
  fscrypt: Factor out a helper to configure the lookup dentry
  ovl: Always reject mounting over case-insensitive directories
  libfs: Attempt exact-match comparison first during casefolded lookup

Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-03-07 11:55:41 +01:00
Gabriel Krisman Bertazi 2824083db7 ovl: Always reject mounting over case-insensitive directories
overlayfs relies on the filesystem setting DCACHE_OP_HASH or
DCACHE_OP_COMPARE to reject mounting over case-insensitive directories.

Since commit bb9cd9106b ("fscrypt: Have filesystems handle their
d_ops"), we set ->d_op through a hook in ->d_lookup, which
means the root dentry won't have them, causing the mount to accidentally
succeed.

In v6.7-rc7, the following sequence will succeed to mount, but any
dentry other than the root dentry will be a "weird" dentry to ovl and
fail with EREMOTE.

  mkfs.ext4 -O casefold lower.img
  mount -O loop lower.img lower
  mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=work ovl /mnt

Mounting on a subdirectory fails, as expected, because DCACHE_OP_HASH
and DCACHE_OP_COMPARE are properly set by ->lookup.

Fix by explicitly rejecting superblocks that allow case-insensitive
dentries. Yes, this will be solved when we move d_op configuration back
to ->s_d_op. Yet, we better have an explicit fix to avoid messing up
again.

While there, re-sort the entries to have more descriptive error messages
first.

Fixes: bb9cd9106b ("fscrypt: Have filesystems handle their d_ops")
Acked-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20240221171412.10710-2-krisman@suse.de
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
2024-02-27 16:55:34 -05:00
Linus Torvalds 716f4aaa7b vfs-6.8-rc5.fixes
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Merge tag 'vfs-6.8-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix performance regression introduced by moving the security
   permission hook out of do_clone_file_range() and into its caller
   vfs_clone_file_range().

   This causes the security hook to be called in situation were it
   wasn't called before as the fast permission checks were left in
   do_clone_file_range().

   Fix this by merging the two implementations back together and
   restoring the old ordering: fast permission checks first, expensive
   ones later.

 - Tweak mount_setattr() permission checking so that mount properties on
   the real rootfs can be changed.

   When we added mount_setattr() we added additional checks compared to
   legacy mount(2). If the mount had a parent then verify that the
   caller and the mount namespace the mount is attached to match and if
   not make sure that it's an anonymous mount.

   But the real rootfs falls into neither category. It is neither an
   anoymous mount because it is obviously attached to the initial mount
   namespace but it also obviously doesn't have a parent mount. So that
   means legacy mount(2) allows changing mount properties on the real
   rootfs but mount_setattr(2) blocks this. This causes regressions (See
   the commit for details).

   Fix this by relaxing the check. If the mount has a parent or if it
   isn't a detached mount, verify that the mount namespaces of the
   caller and the mount are the same. Technically, we could probably
   write this even simpler and check that the mount namespaces match if
   it isn't a detached mount. But the slightly longer check makes it
   clearer what conditions one needs to think about.

* tag 'vfs-6.8-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs: relax mount_setattr() permission checks
  remap_range: merge do_clone_file_range() into vfs_clone_file_range()
2024-02-12 07:15:45 -08:00
Kent Overstreet dd9019604c
ovl: convert to super_set_uuid()
We don't want to be settingc sb->s_uuid directly anymore, as there's a
length field that also has to be set, and this conversion was not
completely trivial.

Acked-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lore.kernel.org/r/20240207025624.1019754-3-kent.overstreet@linux.dev
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: linux-unionfs@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-08 21:20:11 +01:00
Amir Goldstein 853b8d7597
remap_range: merge do_clone_file_range() into vfs_clone_file_range()
commit dfad37051a ("remap_range: move permission hooks out of
do_clone_file_range()") moved the permission hooks from
do_clone_file_range() out to its caller vfs_clone_file_range(),
but left all the fast sanity checks in do_clone_file_range().

This makes the expensive security hooks be called in situations
that they would not have been called before (e.g. fs does not support
clone).

The only reason for the do_clone_file_range() helper was that overlayfs
did not use to be able to call vfs_clone_file_range() from copy up
context with sb_writers lock held.  However, since commit c63e56a4a6
("ovl: do not open/llseek lower file with upper sb_writers held"),
overlayfs just uses an open coded version of vfs_clone_file_range().

Merge_clone_file_range() into vfs_clone_file_range(), restoring the
original order of checks as it was before the regressing commit and adapt
the overlayfs code to call vfs_clone_file_range() before the permission
hooks that were added by commit ca7ab48240 ("ovl: add permission hooks
outside of do_splice_direct()").

Note that in the merge of do_clone_file_range(), the file_start_write()
context was reduced to cover ->remap_file_range() without holding it
over the permission hooks, which was the reason for doing the regressing
commit in the first place.

Reported-and-tested-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401312229.eddeb9a6-oliver.sang@intel.com
Fixes: dfad37051a ("remap_range: move permission hooks out of do_clone_file_range()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20240202102258.1582671-1-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-06 17:07:21 +01:00
Amir Goldstein 11b3f8ae70 fs: remove the inode argument to ->d_real() method
The only remaining user of ->d_real() method is d_real_inode(), which
passed NULL inode argument to get the real data dentry.

There are no longer any users that call ->d_real() with a non-NULL
inode argument for getting a detry from a specific underlying layer.

Remove the inode argument of the method and replace it with an integer
'type' argument, to allow callers to request the real metadata dentry
instead of the real data dentry.

All the current users of d_real_inode() (e.g. uprobe) continue to get
the real data inode.  Caller that need to get the real metadata inode
(e.g. IMA/EVM) can use d_inode(d_real(dentry, D_REAL_METADATA)).

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20240202110132.1584111-3-amir73il@gmail.com
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-06 17:00:12 +01:00
Amir Goldstein 420332b941 ovl: mark xwhiteouts directory with overlay.opaque='x'
An opaque directory cannot have xwhiteouts, so instead of marking an
xwhiteouts directory with a new xattr, overload overlay.opaque xattr
for marking both opaque dir ('y') and xwhiteouts dir ('x').

This is more efficient as the overlay.opaque xattr is checked during
lookup of directory anyway.

This also prevents unnecessary checking the xattr when reading a
directory without xwhiteouts, i.e. most of the time.

Note that the xwhiteouts marker is not checked on the upper layer and
on the last layer in lowerstack, where xwhiteouts are not expected.

Fixes: bc8df7a3dc ("ovl: Add an alternative type of whiteout")
Cc: <stable@vger.kernel.org> # v6.7
Reviewed-by: Alexander Larsson <alexl@redhat.com>
Tested-by: Alexander Larsson <alexl@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2024-01-23 12:39:48 +02:00
Linus Torvalds 499aa1ca4e dcache stuff for this cycle
change of locking rules for __dentry_kill(), regularized refcounting
 rules in that area, assorted cleanups and removal of weird corner
 cases (e.g. now ->d_iput() on child is always called before the parent
 might hit __dentry_kill(), etc.)
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache updates from Al Viro:
 "Change of locking rules for __dentry_kill(), regularized refcounting
  rules in that area, assorted cleanups and removal of weird corner
  cases (e.g. now ->d_iput() on child is always called before the parent
  might hit __dentry_kill(), etc)"

* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits)
  dcache: remove unnecessary NULL check in dget_dlock()
  kill DCACHE_MAY_FREE
  __d_unalias() doesn't use inode argument
  d_alloc_parallel(): in-lookup hash insertion doesn't need an RCU variant
  get rid of DCACHE_GENOCIDE
  d_genocide(): move the extern into fs/internal.h
  simple_fill_super(): don't bother with d_genocide() on failure
  nsfs: use d_make_root()
  d_alloc_pseudo(): move setting ->d_op there from the (sole) caller
  kill d_instantate_anon(), fold __d_instantiate_anon() into remaining caller
  retain_dentry(): introduce a trimmed-down lockless variant
  __dentry_kill(): new locking scheme
  d_prune_aliases(): use a shrink list
  switch select_collect{,2}() to use of to_shrink_list()
  to_shrink_list(): call only if refcount is 0
  fold dentry_kill() into dput()
  don't try to cut corners in shrink_lock_dentry()
  fold the call of retain_dentry() into fast_dput()
  Call retain_dentry() with refcount 0
  dentry_kill(): don't bother with retain_dentry() on slow path
  ...
2024-01-11 20:11:35 -08:00
Linus Torvalds bf4e7080ae fix directory locking scheme on rename
broken in 6.5; we really can't lock two unrelated directories
 without holding ->s_vfs_rename_mutex first and in case of
 same-parent rename of a subdirectory 6.5 ends up doing just
 that.
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull rename updates from Al Viro:
 "Fix directory locking scheme on rename

  This was broken in 6.5; we really can't lock two unrelated directories
  without holding ->s_vfs_rename_mutex first and in case of same-parent
  rename of a subdirectory 6.5 ends up doing just that"

* tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  rename(): avoid a deadlock in the case of parents having no common ancestor
  kill lock_two_inodes()
  rename(): fix the locking of subdirectories
  f2fs: Avoid reading renamed directory if parent does not change
  ext4: don't access the source subdirectory content on same-directory rename
  ext2: Avoid reading renamed directory if parent does not change
  udf_rename(): only access the child content on cross-directory rename
  ocfs2: Avoid touching renamed directory if parent does not change
  reiserfs: Avoid touching renamed directory if parent does not change
2024-01-11 20:00:22 -08:00
Linus Torvalds 4d925f6057 overlayfs updates for 6.8
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Merge tag 'ovl-update-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

Pull overlayfs updates from Amir Goldstein:
 "This is a very small update with no bug fixes and no new features.

  The larger update of overlayfs for this cycle, the re-factoring of
  overlayfs code into generic backing_file helpers, was already merged
  via Christian.

  Summary:

   - Simplify/clarify some code

     No bug fixes here, just some changes following questions from Al
     about overlayfs code that could be a little more simple to follow.

   - Overlayfs documentation style fixes

     Mainly fixes for ReST formatting suggested by documentation
     developers"

* tag 'ovl-update-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  overlayfs.rst: fix ReST formatting
  overlayfs.rst: use consistent feature names
  ovl: initialize ovl_copy_up_ctx.destname inside ovl_do_copy_up()
  ovl: remove redundant ofs->indexdir member
2024-01-10 10:48:22 -08:00
Linus Torvalds 6c1dd1fe5d integrity-v6.8
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Merge tag 'integrity-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity updates from Mimi Zohar:

 - Add a new IMA/EVM maintainer and reviewer

 - Disable EVM on overlayfs

   The EVM HMAC and the original file signatures contain filesystem
   specific metadata (e.g. i_ino, i_generation and s_uuid), preventing
   the security.evm xattr from directly being copied up to the overlay.
   Further before calculating and writing out the overlay file's EVM
   HMAC, EVM must first verify the existing backing file's
   'security.evm' value.

   For now until a solution is developed, disable EVM on overlayfs.

 - One bug fix and two cleanups

* tag 'integrity-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  overlay: disable EVM
  evm: add support to disable EVM on unsupported filesystems
  evm: don't copy up 'security.evm' xattr
  MAINTAINERS: Add Eric Snowberg as a reviewer to IMA
  MAINTAINERS: Add Roberto Sassu as co-maintainer to IMA and EVM
  KEYS: encrypted: Add check for strsep
  ima: Remove EXPERIMENTAL from Kconfig
  ima: Reword IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
2024-01-09 13:24:06 -08:00
Linus Torvalds bb93c5ed45 vfs-6.8.rw
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Merge tag 'vfs-6.8.rw' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs rw updates from Christian Brauner:
 "This contains updates from Amir for read-write backing file helpers
  for stacking filesystems such as overlayfs:

   - Fanotify is currently in the process of introducing pre content
     events. Roughly, a new permission event will be added indicating
     that it is safe to write to the file being accessed. These events
     are used by hierarchical storage managers to e.g., fill the content
     of files on first access.

     During that work we noticed that our current permission checking is
     inconsistent in rw_verify_area() and remap_verify_area().
     Especially in the splice code permission checking is done multiple
     times. For example, one time for the whole range and then again for
     partial ranges inside the iterator.

     In addition, we mostly do permission checking before we call
     file_start_write() except for a few places where we call it after.
     For pre-content events we need such permission checking to be done
     before file_start_write(). So this is a nice reason to clean this
     all up.

     After this series, all permission checking is done before
     file_start_write().

     As part of this cleanup we also massaged the splice code a bit. We
     got rid of a few helpers because we are alredy drowning in special
     read-write helpers. We also cleaned up the return types for splice
     helpers.

   - Introduce generic read-write helpers for backing files. This lifts
     some overlayfs code to common code so it can be used by the FUSE
     passthrough work coming in over the next cycles. Make Amir and
     Miklos the maintainers for this new subsystem of the vfs"

* tag 'vfs-6.8.rw' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (30 commits)
  fs: fix __sb_write_started() kerneldoc formatting
  fs: factor out backing_file_mmap() helper
  fs: factor out backing_file_splice_{read,write}() helpers
  fs: factor out backing_file_{read,write}_iter() helpers
  fs: prepare for stackable filesystems backing file helpers
  fsnotify: optionally pass access range in file permission hooks
  fsnotify: assert that file_start_write() is not held in permission hooks
  fsnotify: split fsnotify_perm() into two hooks
  fs: use splice_copy_file_range() inline helper
  splice: return type ssize_t from all helpers
  fs: use do_splice_direct() for nfsd/ksmbd server-side-copy
  fs: move file_start_write() into direct_splice_actor()
  fs: fork splice_file_range() from do_splice_direct()
  fs: create {sb,file}_write_not_started() helpers
  fs: create file_write_started() helper
  fs: create __sb_write_started() helper
  fs: move kiocb_start_write() into vfs_iocb_iter_write()
  fs: move permission hook out of do_iter_read()
  fs: move permission hook out of do_iter_write()
  fs: move file_start_write() into vfs_iter_write()
  ...
2024-01-08 11:11:51 -08:00
Amir Goldstein f567377e40 fs: factor out backing_file_mmap() helper
Assert that the file object is allocated in a backing_file container
so that file_user_path() could be used to display the user path and
not the backing file's path in /proc/<pid>/maps.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-12-23 16:35:09 +02:00
Amir Goldstein 9b7e9e2f5d fs: factor out backing_file_splice_{read,write}() helpers
There is not much in those helpers, but it makes sense to have them
logically next to the backing_file_{read,write}_iter() helpers as they
may grow more common logic in the future.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-12-23 16:35:09 +02:00
Amir Goldstein a6293b3e28 fs: factor out backing_file_{read,write}_iter() helpers
Overlayfs submits files io to backing files on other filesystems.
Factor out some common helpers to perform io to backing files, into
fs/backing-file.c.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/r/CAJfpeguhmZbjP3JLqtUy0AdWaHOkAPWeP827BBWwRFEAUgnUcQ@mail.gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-12-23 16:35:09 +02:00
Amir Goldstein f91a704f71 fs: prepare for stackable filesystems backing file helpers
In preparation for factoring out some backing file io helpers from
overlayfs, move backing_file_open() into a new file fs/backing-file.c
and header.

Add a MAINTAINERS entry for stackable filesystems and add a Kconfig
FS_STACK which stackable filesystems need to select.

For now, the backing_file struct, the backing_file alloc/free functions
and the backing_file_real_path() accessor remain internal to file_table.c.
We may change that in the future.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-12-23 16:35:08 +02:00
Linus Torvalds 1a44b0073b overlayfs fixes for 6.7-rc7
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Merge tag 'ovl-fixes-6.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

Pull overlayfs fix from Amir Goldstein:
 "Fix a regression from this merge window"

* tag 'ovl-fixes-6.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: fix dentry reference leak after changes to underlying layers
2023-12-20 12:04:03 -08:00
Mimi Zohar c00f94b3a5 overlay: disable EVM
Until a complete solution is developed, update 'sb->s_iflags' to
disable EVM.

Acked-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2023-12-20 07:40:50 -05:00
Amir Goldstein 413ba91089 ovl: fix dentry reference leak after changes to underlying layers
syzbot excercised the forbidden practice of moving the workdir under
lowerdir while overlayfs is mounted and tripped a dentry reference leak.

Fixes: c63e56a4a6 ("ovl: do not open/llseek lower file with upper sb_writers held")
Reported-and-tested-by: syzbot+8608bb4553edb8c78f41@syzkaller.appspotmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-12-17 13:33:46 +02:00
Amir Goldstein 0f292086c2
splice: return type ssize_t from all helpers
Not sure why some splice helpers return long, maybe historic reasons.
Change them all to return ssize_t to conform to the splice methods and
to the rest of the helpers.

Suggested-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20231208-horchen-helium-d3ec1535ede5@brauner/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231212094440.250945-2-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-12-12 16:19:59 +01:00
Amir Goldstein da40448ce4 fs: move file_start_write() into direct_splice_actor()
The callers of do_splice_direct() hold file_start_write() on the output
file.

This may cause file permission hooks to be called indirectly on an
overlayfs lower layer, which is on the same filesystem of the output
file and could lead to deadlock with fanotify permission events.

To fix this potential deadlock, move file_start_write() from the callers
into the direct_splice_actor(), so file_start_write() will not be held
while splicing from the input file.

Suggested-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20231128214258.GA2398475@perftesting/
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231130141624.3338942-3-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-12-01 11:39:50 +01:00
Al Viro a8b0026847 rename(): avoid a deadlock in the case of parents having no common ancestor
... and fix the directory locking documentation and proof of correctness.
Holding ->s_vfs_rename_mutex *almost* prevents ->d_parent changes; the
case where we really don't want it is splicing the root of disconnected
tree to somewhere.

In other words, ->s_vfs_rename_mutex is sufficient to stabilize "X is an
ancestor of Y" only if X and Y are already in the same tree.  Otherwise
it can go from false to true, and one can construct a deadlock on that.

Make lock_two_directories() report an error in such case and update the
callers of lock_rename()/lock_rename_child() to handle such errors.

And yes, such conditions are not impossible to create ;-/

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2023-11-25 02:54:14 -05:00
Linus Torvalds fa2b906f51 vfs-6.7-rc3.fixes
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Merge tag 'vfs-6.7-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Avoid calling back into LSMs from vfs_getattr_nosec() calls.

   IMA used to query inode properties accessing raw inode fields without
   dedicated helpers. That was finally fixed a few releases ago by
   forcing IMA to use vfs_getattr_nosec() helpers.

   The goal of the vfs_getattr_nosec() helper is to query for attributes
   without calling into the LSM layer which would be quite problematic
   because incredibly IMA is called from __fput()...

     __fput()
       -> ima_file_free()

   What it does is to call back into the filesystem to update the file's
   IMA xattr. Querying the inode without using vfs_getattr_nosec() meant
   that IMA didn't handle stacking filesystems such as overlayfs
   correctly. So the switch to vfs_getattr_nosec() is quite correct. But
   the switch to vfs_getattr_nosec() revealed another bug when used on
   stacking filesystems:

     __fput()
       -> ima_file_free()
          -> vfs_getattr_nosec()
             -> i_op->getattr::ovl_getattr()
                -> vfs_getattr()
                   -> i_op->getattr::$WHATEVER_UNDERLYING_FS_getattr()
                      -> security_inode_getattr() # calls back into LSMs

   Now, if that __fput() happens from task_work_run() of an exiting task
   current->fs and various other pointer could already be NULL. So
   anything in the LSM layer relying on that not being NULL would be
   quite surprised.

   Fix that by passing the information that this is a security request
   through to the stacking filesystem by adding a new internal
   ATT_GETATTR_NOSEC flag. Now the callchain becomes:

     __fput()
       -> ima_file_free()
          -> vfs_getattr_nosec()
             -> i_op->getattr::ovl_getattr()
                -> if (AT_GETATTR_NOSEC)
                          vfs_getattr_nosec()
                   else
                          vfs_getattr()
                   -> i_op->getattr::$WHATEVER_UNDERLYING_FS_getattr()

 - Fix a bug introduced with the iov_iter rework from last cycle.

   This broke /proc/kcore by copying too much and without the correct
   offset.

 - Add a missing NULL check when allocating the root inode in
   autofs_fill_super().

 - Fix stable writes for multi-device filesystems (xfs, btrfs etc) and
   the block device pseudo filesystem.

   Stable writes used to be a superblock flag only, making it a per
   filesystem property. Add an additional AS_STABLE_WRITES mapping flag
   to allow for fine-grained control.

 - Ensure that offset_iterate_dir() returns 0 after reaching the end of
   a directory so it adheres to getdents() convention.

* tag 'vfs-6.7-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  libfs: getdents() should return 0 after reaching EOD
  xfs: respect the stable writes flag on the RT device
  xfs: clean up FS_XFLAG_REALTIME handling in xfs_ioctl_setattr_xflags
  block: update the stable_writes flag in bdev_add
  filemap: add a per-mapping stable writes flag
  autofs: add: new_inode check in autofs_fill_super()
  iov_iter: fix copy_page_to_iter_nofault()
  fs: Pass AT_GETATTR_NOSEC flag to getattr interface function
2023-11-24 09:45:40 -08:00
Amir Goldstein 6ae654392b fs: move kiocb_start_write() into vfs_iocb_iter_write()
In vfs code, sb_start_write() is usually called after the permission hook
in rw_verify_area().  vfs_iocb_iter_write() is an exception to this rule,
where kiocb_start_write() is called by its callers.

Move kiocb_start_write() from the callers into vfs_iocb_iter_write()
after the rw_verify_area() checks, to make them "start-write-safe".

The semantics of vfs_iocb_iter_write() is changed, so that the caller is
responsible for calling kiocb_end_write() on completion only if async
iocb was queued.  The completion handlers of both callers were adapted
to this semantic change.

This is needed for fanotify "pre content" events.

Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-14-amir73il@gmail.com
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-24 10:37:44 +01:00
Amir Goldstein 269aed7014 fs: move file_start_write() into vfs_iter_write()
All the callers of vfs_iter_write() call file_start_write() just before
calling vfs_iter_write() except for target_core_file's fd_do_rw().

Move file_start_write() from the callers into vfs_iter_write().
fd_do_rw() calls vfs_iter_write() with a non-regular file, so
file_start_write() is a no-op.

This is needed for fanotify "pre content" events.

Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-11-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-24 10:09:51 +01:00
Amir Goldstein ca7ab48240 ovl: add permission hooks outside of do_splice_direct()
The main callers of do_splice_direct() also call rw_verify_area() for
the entire range that is being copied, e.g. by vfs_copy_file_range()
or do_sendfile() before calling do_splice_direct().

The only caller that does not have those checks for entire range is
ovl_copy_up_file().  In preparation for removing the checks inside
do_splice_direct(), add rw_verify_area() call in ovl_copy_up_file().

For extra safety, perform minimal sanity checks from rw_verify_area()
for non negative offsets also in the copy up do_splice_direct() loop
without calling the file permission hooks.

This is needed for fanotify "pre content" events.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-2-amir73il@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-24 09:22:27 +01:00
Amir Goldstein 2c3ef4f89c ovl: initialize ovl_copy_up_ctx.destname inside ovl_do_copy_up()
The ->destname member of struct ovl_copy_up_ctx is initialized inside
ovl_copy_up_one() to ->d_name of the overlayfs dentry being copied up
and then it may be overridden by index name inside ovl_do_copy_up().

ovl_inode_lock() in ovl_copy_up_start() and ovl_copy_up() in ovl_rename()
effectively stabilze ->d_name of the overlayfs dentry being copied up,
but ovl_inode_lock() is not held when ->d_name is being read.

It is not a correctness bug, because if ovl_do_copy_up() races with
ovl_rename() and ctx.destname is freed, we will not end up calling
ovl_do_copy_up() with the dead name reference.

The code becomes much easier to understand and to document if the
initialization of c->destname is always done inside ovl_do_copy_up(),
either to the index entry name, or to the overlay dentry ->d_name.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-11-20 16:01:45 +02:00
Amir Goldstein 02d70090e0 ovl: remove redundant ofs->indexdir member
When the index feature is disabled, ofs->indexdir is NULL.
When the index feature is enabled, ofs->indexdir has the same value as
ofs->workdir and takes an extra reference.

This makes the code harder to understand when it is not always clear
that ofs->indexdir in one function is the same dentry as ofs->workdir
in another function.

Remove this redundancy, by referencing ofs->workdir directly in index
helpers and by using the ovl_indexdir() accessor in generic code.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-11-20 09:49:09 +02:00
Amir Goldstein 484d4fbfda ovl: stop using d_alloc_anon()/d_instantiate_anon()
Commit f9c34674bc ("vfs: factor out helpers d_instantiate_anon() and
d_alloc_anon()") was introduced so overlayfs could initialize a non-dir
disconnected overlay dentry before overlay inode is attached to it.

Since commit ("0af950f57fef ovl: move ovl_entry into ovl_inode"), all
ovl_obtain_alias() can do is set DCACHE_OP_*REVALIDATE flags in ->d_flags
and OVL_E_UPPER_ALIAS flag in ->d_fsdata.

The DCACHE_OP_*REVALIDATE flags and OVL_E_UPPER_ALIAS flag are irrelevant
for a disconnected non-dir dentry, so it is better to use d_obtain_alias()
instead of open coding it.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2023-11-18 16:15:19 -05:00
Stefan Berger 8a924db2d7 fs: Pass AT_GETATTR_NOSEC flag to getattr interface function
When vfs_getattr_nosec() calls a filesystem's getattr interface function
then the 'nosec' should propagate into this function so that
vfs_getattr_nosec() can again be called from the filesystem's gettattr
rather than vfs_getattr(). The latter would add unnecessary security
checks that the initial vfs_getattr_nosec() call wanted to avoid.
Therefore, introduce the getattr flag GETATTR_NOSEC and allow to pass
with the new getattr_flags parameter to the getattr interface function.
In overlayfs and ecryptfs use this flag to determine which one of the
two functions to call.

In a recent code change introduced to IMA vfs_getattr_nosec() ended up
calling vfs_getattr() in overlayfs, which in turn called
security_inode_getattr() on an exiting process that did not have
current->fs set anymore, which then caused a kernel NULL pointer
dereference. With this change the call to security_inode_getattr() can
be avoided, thus avoiding the NULL pointer dereference.

Reported-by: <syzbot+a67fc5321ffb4b311c98@syzkaller.appspotmail.com>
Fixes: db1d1e8b98 ("IMA: use vfs_getattr_nosec to get the i_version")
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Tyler Hicks <code@tyhicks.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Suggested-by: Christian Brauner <brauner@kernel.org>
Co-developed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Link: https://lore.kernel.org/r/20231002125733.1251467-1-stefanb@linux.vnet.ibm.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-18 14:54:07 +01:00
Amir Goldstein 37f32f5264 ovl: fix memory leak in ovl_parse_param()
On failure to parse parameters in ovl_parse_param_lowerdir(), it is
necessary to update ctx->nr with the correct nr before using
ovl_reset_lowerdirs() to release l->name.

Reported-and-tested-by: syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com
Fixes: c835110b58 ("ovl: remove unused code in lowerdir param parsing")
Co-authored-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-11-14 08:09:36 +02:00
Amir Goldstein b28060db71 ovl: fix misformatted comment
Remove misleading /** prefix from a regular comment.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311121628.byHp8tkv-lkp@intel.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-11-14 08:09:36 +02:00
Linus Torvalds 13d88ac54d vfs-6.7.fsid
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Merge tag 'vfs-6.7.fsid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fanotify fsid updates from Christian Brauner:
 "This work is part of the plan to enable fanotify to serve as a drop-in
  replacement for inotify. While inotify is availabe on all filesystems,
  fanotify currently isn't.

  In order to support fanotify on all filesystems two things are needed:

   (1) all filesystems need to support AT_HANDLE_FID

   (2) all filesystems need to report a non-zero f_fsid

  This contains (1) and allows filesystems to encode non-decodable file
  handlers for fanotify without implementing any exportfs operations by
  encoding a file id of type FILEID_INO64_GEN from i_ino and
  i_generation.

  Filesystems that want to opt out of encoding non-decodable file ids
  for fanotify that don't support NFS export can do so by providing an
  empty export_operations struct.

  This also partially addresses (2) by generating f_fsid for simple
  filesystems as well as freevxfs. Remaining filesystems will be dealt
  with by separate patches.

  Finally, this contains the patch from the current exportfs maintainers
  which moves exportfs under vfs with Chuck, Jeff, and Amir as
  maintainers and vfs.git as tree"

* tag 'vfs-6.7.fsid' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  MAINTAINERS: create an entry for exportfs
  fs: fix build error with CONFIG_EXPORTFS=m or not defined
  freevxfs: derive f_fsid from bdev->bd_dev
  fs: report f_fsid from s_dev for "simple" filesystems
  exportfs: support encoding non-decodeable file handles by default
  exportfs: define FILEID_INO64_GEN* file handle types
  exportfs: make ->encode_fh() a mandatory method for NFS export
  exportfs: add helpers to check if filesystem can encode/decode file handles
2023-11-07 12:11:26 -08:00
Linus Torvalds 7f851936a0 overlayfs update for 6.7-rc1
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Merge tag 'ovl-update-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

Pull overlayfs updates from Amir Goldstein:

 - Overlayfs aio cleanups and fixes

   Cleanups and minor fixes in preparation for factoring out of
   read/write passthrough code.

 - Overlayfs lock ordering changes

   Hold mnt_writers only throughout copy up instead of a long lived
   elevated refcount.

 - Add support for nesting overlayfs private xattrs

   There are cases where you want to use an overlayfs mount as a
   lowerdir for another overlayfs mount. For example, if the system
   rootfs is on overlayfs due to composefs, or to make it volatile (via
   tmpfs), then you cannot currently store a lowerdir on the rootfs,
   because the inner overlayfs will eat all the whiteouts and overlay
   xattrs. This means you can't e.g. store on the rootfs a prepared
   container image for use with overlayfs.

   This adds support for nesting of overlayfs mounts by escaping the
   problematic features and unescaping them when exposing to the
   overlayfs user.

 - Add new mount options for appending lowerdirs

* tag 'ovl-update-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: add support for appending lowerdirs one by one
  ovl: refactor layer parsing helpers
  ovl: store and show the user provided lowerdir mount option
  ovl: remove unused code in lowerdir param parsing
  ovl: Add documentation on nesting of overlayfs mounts
  ovl: Add an alternative type of whiteout
  ovl: Support escaped overlay.* xattrs
  ovl: Add OVL_XATTR_TRUSTED/USER_PREFIX_LEN macros
  ovl: Move xattr support to new xattrs.c file
  ovl: do not encode lower fh with upper sb_writers held
  ovl: do not open/llseek lower file with upper sb_writers held
  ovl: reorder ovl_want_write() after ovl_inode_lock()
  ovl: split ovl_want_write() into two helpers
  ovl: add helper ovl_file_modified()
  ovl: protect copying of realinode attributes to ovl inode
  ovl: punt write aio completion to workqueue
  ovl: propagate IOCB_APPEND flag on writes to realfile
  ovl: use simpler function to convert iocb to rw flags
2023-11-07 11:46:31 -08:00
Linus Torvalds ca219be012 integrity-v6.7
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Merge tag 'integrity-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity updates from Mimi Zohar:
 "Four integrity changes: two IMA-overlay updates, an integrity Kconfig
  cleanup, and a secondary keyring update"

* tag 'integrity-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: detect changes to the backing overlay file
  certs: Only allow certs signed by keys on the builtin keyring
  integrity: fix indentation of config attributes
  ima: annotate iint mutex to avoid lockdep false positive warnings
2023-11-02 06:53:22 -10:00
Mimi Zohar b836c4d29f ima: detect changes to the backing overlay file
Commit 18b44bc5a6 ("ovl: Always reevaluate the file signature for
IMA") forced signature re-evaulation on every file access.

Instead of always re-evaluating the file's integrity, detect a change
to the backing file, by comparing the cached file metadata with the
backing file's metadata.  Verifying just the i_version has not changed
is insufficient.  In addition save and compare the i_ino and s_dev
as well.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Tested-by: Eric Snowberg <eric.snowberg@oracle.com>
Tested-by: Raul E Rangel <rrangel@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2023-10-31 08:22:36 -04:00
Amir Goldstein 24e16e385f ovl: add support for appending lowerdirs one by one
Add new mount options lowerdir+ and datadir+ that can be used to add
layers to lower layers stack one by one.

Unlike the legacy lowerdir mount option, special characters (i.e. colons
and cammas) are not unescaped with these new mount options.

The new mount options can be repeated to compose a large stack of lower
layers, but they may not be mixed with the lagacy lowerdir mount option,
because for displaying lower layers in mountinfo, we do not want to mix
escaped with unescaped lower layers path syntax.

Similar to data-only layer rules with the lowerdir mount option, the
datadir+ option must follow at least one lowerdir+ option and the
lowerdir+ option must not follow the datadir+ option.

If the legacy lowerdir mount option follows lowerdir+ and datadir+
mount options, it overrides them.  Sepcifically, calling:

  fsconfig(FSCONFIG_SET_STRING, "lowerdir", "", 0);

can be used to reset previously setup lower layers.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/r/CAJfpegt7VC94KkRtb1dfHG8+4OzwPBLYqhtc8=QFUxpFJE+=RQ@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-10-31 00:13:02 +02:00
Amir Goldstein 819829f031 ovl: refactor layer parsing helpers
In preparation for new mount options to add lowerdirs one by one,
generalize ovl_parse_param_upperdir() into helper ovl_parse_layer()
that will be used for parsing a single lower layers.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/r/CAJfpegt7VC94KkRtb1dfHG8+4OzwPBLYqhtc8=QFUxpFJE+=RQ@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-10-31 00:13:02 +02:00
Amir Goldstein 0cea4c097d ovl: store and show the user provided lowerdir mount option
We are about to add new mount options for adding lowerdir one by one,
but those mount options will not support escaping.

For the existing case, where lowerdir mount option is provided as a colon
separated list, store the user provided (possibly escaped) string and
display it as is when showing the lowerdir mount option.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-10-31 00:13:02 +02:00
Amir Goldstein c835110b58 ovl: remove unused code in lowerdir param parsing
Commit beae836e9c ("ovl: temporarily disable appending lowedirs")
removed the ability to append lowerdirs with syntax lowerdir=":<path>".
Remove leftover code and comments that are irrelevant with lowerdir
append mode disabled.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-10-31 00:13:02 +02:00
Alexander Larsson bc8df7a3dc ovl: Add an alternative type of whiteout
An xattr whiteout (called "xwhiteout" in the code) is a reguar file of
zero size with the "overlay.whiteout" xattr set. A file like this in a
directory with the "overlay.whiteouts" xattrs set will be treated the
same way as a regular whiteout.

The "overlay.whiteouts" directory xattr is used in order to
efficiently handle overlay checks in readdir(), as we only need to
checks xattrs in affected directories.

The advantage of this kind of whiteout is that they can be escaped
using the standard overlay xattr escaping mechanism. So, a file with a
"overlay.overlay.whiteout" xattr would be unescaped to
"overlay.whiteout", which could then be consumed by another overlayfs
as a whiteout.

Overlayfs itself doesn't create whiteouts like this, but a userspace
mechanism could use this alternative mechanism to convert images that
may contain whiteouts to be used with overlayfs.

To work as a whiteout for both regular overlayfs mounts as well as
userxattr mounts both the "user.overlay.whiteout*" and the
"trusted.overlay.whiteout*" xattrs will need to be created.

Signed-off-by: Alexander Larsson <alexl@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-10-31 00:12:59 +02:00
Alexander Larsson dad02fad84 ovl: Support escaped overlay.* xattrs
There are cases where you want to use an overlayfs mount as a lowerdir
for another overlayfs mount. For example, if the system rootfs is on
overlayfs due to composefs, or to make it volatile (via tmps), then
you cannot currently store a lowerdir on the rootfs. This means you
can't e.g. store on the rootfs a prepared container image for use
using overlayfs.

To work around this, we introduce an escapment mechanism for overlayfs
xattrs. Whenever the lower/upper dir has a xattr named
"overlay.overlay.XYZ", we list it as "overlay.XYZ" in listxattrs, and
when the user calls getxattr or setxattr on "overlay.XYZ", we apply to
"overlay.overlay.XYZ" in the backing directories.

This allows storing any kind of overlay xattrs in a overlayfs mount
that can be used as a lowerdir in another mount. It is possible to
stack this mechanism multiple times, such that
"overlay.overlay.overlay.XYZ" will survive two levels of overlay mounts,
however this is not all that useful in practice because of stack depth
limitations of overlayfs mounts.

Note: These escaped xattrs are copied to upper during copy-up.

Signed-off-by: Alexander Larsson <alexl@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
2023-10-31 00:12:59 +02:00