When a key is added, existing directory dentries in the
DCACHE_NOKEY_NAME form are moved by the VFS to the plaintext version.
But, since they have the DCACHE_OP_REVALIDATE flag set, revalidation
will be done at each lookup only to return immediately, since plaintext
dentries can't go stale until eviction. This patch optimizes this case,
by dropping the flag once the nokey_name dentry becomes plain-text.
Note that non-directory dentries are not moved this way, so they won't
be affected.
Of course, this can only be done if fscrypt is the only thing requiring
revalidation for a dentry. For this reason, we only disable
d_revalidate if the .d_revalidate hook is fscrypt_d_revalidate itself.
It is safe to do it here because when moving the dentry to the
plain-text version, we are holding the d_lock. We might race with a
concurrent RCU lookup but this is harmless because, at worst, we will
get an extra d_revalidate on the keyed dentry, which will still find the
dentry to be valid.
Finally, now that we do more than just clear the DCACHE_NOKEY_NAME in
fscrypt_handle_d_move, skip it entirely for plaintext dentries, to avoid
extra costs.
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20240221171412.10710-5-krisman@suse.de
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Unencrypted and encrypted-dentries where the key is available don't need
to be revalidated by fscrypt, since they don't go stale from under VFS
and the key cannot be removed for the encrypted case without evicting
the dentry. Disable their d_revalidate hook on the first lookup, to
avoid repeated revalidation later. This is done in preparation to always
configuring d_op through sb->s_d_op.
The only part detail is that, since the filesystem might have other
features that require revalidation, we only apply this optimization if
the d_revalidate handler is fscrypt_d_revalidate itself.
Finally, we need to clean the dentry->flags even for unencrypted
dentries, so the ->d_lock might be acquired even for them. In order to
avoid doing it for filesystems that don't care about fscrypt at all, we
peek ->d_flags without the lock at first, and only acquire it if we
actually need to write the flag.
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20240221171412.10710-4-krisman@suse.de
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Both fscrypt_prepare_lookup_partial and fscrypt_prepare_lookup will set
DCACHE_NOKEY_NAME for dentries when the key is not available. Extract
out a helper to set this flag in a single place, in preparation to also
add the optimization that will disable ->d_revalidate if possible.
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20240221171412.10710-3-krisman@suse.de
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
We are going to track per-extent information, so it'll be necessary to
distinguish between inode infos and extent infos. Rename fscrypt_info
to fscrypt_inode_info, adjusting any lines that now exceed 80
characters.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ebiggers: rebased onto fscrypt tree, renamed fscrypt_get_info(),
adjusted two comments, and fixed some lines over 80 characters]
Link: https://lore.kernel.org/r/20231005025757.33521-1-ebiggers@kernel.org
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Until now, fscrypt has always used the filesystem block size as the
granularity of file contents encryption. Two scenarios have come up
where a sub-block granularity of contents encryption would be useful:
1. Inline crypto hardware that only supports a crypto data unit size
that is less than the filesystem block size.
2. Support for direct I/O at a granularity less than the filesystem
block size, for example at the block device's logical block size in
order to match the traditional direct I/O alignment requirement.
(1) first came up with older eMMC inline crypto hardware that only
supports a crypto data unit size of 512 bytes. That specific case
ultimately went away because all systems with that hardware continued
using out of tree code and never actually upgraded to the upstream
inline crypto framework. But, now it's coming back in a new way: some
current UFS controllers only support a data unit size of 4096 bytes, and
there is a proposal to increase the filesystem block size to 16K.
(2) was discussed as a "nice to have" feature, though not essential,
when support for direct I/O on encrypted files was being upstreamed.
Still, the fact that this feature has come up several times does suggest
it would be wise to have available. Therefore, this patch implements it
by using one of the reserved bytes in fscrypt_policy_v2 to allow users
to select a sub-block data unit size. Supported data unit sizes are
powers of 2 between 512 and the filesystem block size, inclusively.
Support is implemented for both the FS-layer and inline crypto cases.
This patch focuses on the basic support for sub-block data units. Some
things are out of scope for this patch but may be addressed later:
- Supporting sub-block data units in combination with
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64, in most cases. Unfortunately this
combination usually causes data unit indices to exceed 32 bits, and
thus fscrypt_supported_policy() correctly disallows it. The users who
potentially need this combination are using f2fs. To support it, f2fs
would need to provide an option to slightly reduce its max file size.
- Supporting sub-block data units in combination with
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32. This has the same problem
described above, but also it will need special code to make DUN
wraparound still happen on a FS block boundary.
- Supporting use case (2) mentioned above. The encrypted direct I/O
code will need to stop requiring and assuming FS block alignment.
This won't be hard, but it belongs in a separate patch.
- Supporting this feature on filesystems other than ext4 and f2fs.
(Filesystems declare support for it via their fscrypt_operations.)
On UBIFS, sub-block data units don't make sense because UBIFS encrypts
variable-length blocks as a result of compression. CephFS could
support it, but a bit more work would be needed to make the
fscrypt_*_block_inplace functions play nicely with sub-block data
units. I don't think there's a use case for this on CephFS anyway.
Link: https://lore.kernel.org/r/20230925055451.59499-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Now that fs/crypto/ computes the filesystem's lblk_bits from its maximum
file size, it is no longer necessary for filesystems to provide
lblk_bits via fscrypt_operations::get_ino_and_lblk_bits.
It is still necessary for fs/crypto/ to retrieve ino_bits from the
filesystem. However, this is used only to decide whether inode numbers
fit in 32 bits. Also, ino_bits is static for all relevant filesystems,
i.e. it doesn't depend on the filesystem instance.
Therefore, in the interest of keeping things as simple as possible,
replace 'get_ino_and_lblk_bits' with a flag 'has_32bit_inodes'. This
can always be changed back to a function if a filesystem needs it to be
dynamic, but for now a static flag is all that's needed.
Link: https://lore.kernel.org/r/20230925055451.59499-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Replace FS_CFLG_OWN_PAGES with a bit flag 'needs_bounce_pages' which has
the opposite meaning. I.e., filesystems now opt into the bounce page
pool instead of opt out. Make fscrypt_alloc_bounce_page() check that
the bounce page pool has been initialized.
I believe the opt-in makes more sense, since nothing else in
fscrypt_operations is opt-out, and these days filesystems can choose to
use blk-crypto which doesn't need the fscrypt bounce page pool. Also, I
happen to be planning to add two more flags, and I wanted to fix the
"FS_CFLG_" name anyway as it wasn't prefixed with "FSCRYPT_".
Link: https://lore.kernel.org/r/20230925055451.59499-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
fscrypt_operations::key_prefix should not be set by any filesystems that
aren't setting it already. This is already documented, but apparently
it's not sufficiently clear, as both ceph and btrfs have tried to set
it. Rename the field to legacy_key_prefix and improve the documentation
to hopefully make it clearer.
Link: https://lore.kernel.org/r/20230925055451.59499-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
* The data=journal writepath has been significantly cleaned up and
simplified, and reduces a large number of data=journal special cases
by Jan Kara.
* Ojaswin Muhoo has replaced linked list used to track extents that
have been used for inode preallocation with a red-black tree in the
multi-block allocator. This improves performance for workloads
which do a large number of random allocating writes.
* Thanks to Kemeng Shi for a lot of cleanup and bug fixes in the
multi-block allocator.
* Matthew wilcox has converted the code paths for reading and writing
ext4 pages to use folios.
* Jason Yan has continued to factor out ext4_fill_super() into smaller
functions for improve ease of maintenance and comprehension.
* Josh Triplett has created an uapi header for ext4 userspace API's.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"There are a number of major cleanups in ext4 this cycle:
- The data=journal writepath has been significantly cleaned up and
simplified, and reduces a large number of data=journal special
cases by Jan Kara.
- Ojaswin Muhoo has replaced linked list used to track extents that
have been used for inode preallocation with a red-black tree in the
multi-block allocator. This improves performance for workloads
which do a large number of random allocating writes.
- Thanks to Kemeng Shi for a lot of cleanup and bug fixes in the
multi-block allocator.
- Matthew wilcox has converted the code paths for reading and writing
ext4 pages to use folios.
- Jason Yan has continued to factor out ext4_fill_super() into
smaller functions for improve ease of maintenance and
comprehension.
- Josh Triplett has created an uapi header for ext4 userspace API's"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (105 commits)
ext4: Add a uapi header for ext4 userspace APIs
ext4: remove useless conditional branch code
ext4: remove unneeded check of nr_to_submit
ext4: move dax and encrypt checking into ext4_check_feature_compatibility()
ext4: factor out ext4_block_group_meta_init()
ext4: move s_reserved_gdt_blocks and addressable checking into ext4_check_geometry()
ext4: rename two functions with 'check'
ext4: factor out ext4_flex_groups_free()
ext4: use ext4_group_desc_free() in ext4_put_super() to save some duplicated code
ext4: factor out ext4_percpu_param_init() and ext4_percpu_param_destroy()
ext4: factor out ext4_hash_info_init()
Revert "ext4: Fix warnings when freezing filesystem with journaled data"
ext4: Update comment in mpage_prepare_extent_to_map()
ext4: Simplify handling of journalled data in ext4_bmap()
ext4: Drop special handling of journalled data from ext4_quota_on()
ext4: Drop special handling of journalled data from ext4_evict_inode()
ext4: Fix special handling of journalled data from extent zeroing
ext4: Drop special handling of journalled data from extent shifting operations
ext4: Drop special handling of journalled data from ext4_sync_file()
ext4: Commit transaction before writing back pages in data=journal mode
...
fscrypt_is_bounce_folio() is the equivalent of fscrypt_is_bounce_page()
and fscrypt_pagecache_folio() is the equivalent of fscrypt_pagecache_page().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230324180129.1220691-3-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This patch introduces a new helper function which can be used both in
lookups and in atomic_open operations by filesystems that want to handle
filename encryption and no-key dentries themselves.
The reason for this function to be used in atomic open is that this
operation can act as a lookup if handed a dentry that is negative. And in
this case we may need to set DCACHE_NOKEY_NAME.
Signed-off-by: Luís Henriques <lhenriques@suse.de>
Tested-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
[ebiggers: improved the function comment, and moved the function to just
below __fscrypt_prepare_lookup()]
Link: https://lore.kernel.org/r/20230320220149.21863-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Fix the longstanding implementation limitation that fsverity was only
supported when the Merkle tree block size, filesystem block size, and
PAGE_SIZE were all equal. Specifically, add support for Merkle tree
block sizes less than PAGE_SIZE, and make ext4 support fsverity on
filesystems where the filesystem block size is less than PAGE_SIZE.
Effectively, this means that fsverity can now be used on systems with
non-4K pages, at least on ext4. These changes have been tested using
the verity group of xfstests, newly updated to cover the new code paths.
Also update fs/verity/ to support verifying data from large folios.
There's also a similar patch for fs/crypto/, to support decrypting data
from large folios, which I'm including in this pull request to avoid a
merge conflict between the fscrypt and fsverity branches.
There will be a merge conflict in fs/buffer.c with some of the foliation
work in the mm tree. Please use the merge resolution from linux-next.
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Merge tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fsverity/linux
Pull fsverity updates from Eric Biggers:
"Fix the longstanding implementation limitation that fsverity was only
supported when the Merkle tree block size, filesystem block size, and
PAGE_SIZE were all equal.
Specifically, add support for Merkle tree block sizes less than
PAGE_SIZE, and make ext4 support fsverity on filesystems where the
filesystem block size is less than PAGE_SIZE.
Effectively, this means that fsverity can now be used on systems with
non-4K pages, at least on ext4. These changes have been tested using
the verity group of xfstests, newly updated to cover the new code
paths.
Also update fs/verity/ to support verifying data from large folios.
There's also a similar patch for fs/crypto/, to support decrypting
data from large folios, which I'm including in here to avoid a merge
conflict between the fscrypt and fsverity branches"
* tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fsverity/linux:
fscrypt: support decrypting data from large folios
fsverity: support verifying data from large folios
fsverity.rst: update git repo URL for fsverity-utils
ext4: allow verity with fs block size < PAGE_SIZE
fs/buffer.c: support fsverity in block_read_full_folio()
f2fs: simplify f2fs_readpage_limit()
ext4: simplify ext4_readpage_limit()
fsverity: support enabling with tree block size < PAGE_SIZE
fsverity: support verification with tree block size < PAGE_SIZE
fsverity: replace fsverity_hash_page() with fsverity_hash_block()
fsverity: use EFBIG for file too large to enable verity
fsverity: store log2(digest_size) precomputed
fsverity: simplify Merkle tree readahead size calculation
fsverity: use unsigned long for level_start
fsverity: remove debug messages and CONFIG_FS_VERITY_DEBUG
fsverity: pass pos and size to ->write_merkle_tree_block
fsverity: optimize fsverity_cleanup_inode() on non-verity files
fsverity: optimize fsverity_prepare_setattr() on non-verity files
fsverity: optimize fsverity_file_open() on non-verity files
Now that fscrypt_add_test_dummy_key() is only called by
setup_file_encryption_key() and not by the individual filesystems,
un-export it. Also change its prototype to take the
fscrypt_key_specifier directly, as the caller already has it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230208062107.199831-6-ebiggers@kernel.org
Try to make the filesystem-level decryption functions in fs/crypto/
aware of large folios. This includes making fscrypt_decrypt_bio()
support the case where the bio contains large folios, and making
fscrypt_decrypt_pagecache_blocks() take a folio instead of a page.
There's no way to actually test this with large folios yet, but I've
tested that this doesn't cause any regressions.
Note that this patch just handles *decryption*, not encryption which
will be a little more difficult.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230127224202.355629-1-ebiggers@kernel.org
Commit d7e7b9af10 ("fscrypt: stop using keyrings subsystem for
fscrypt_master_key") moved the keyring destruction from __put_super() to
generic_shutdown_super() so that the filesystem's block device(s) are
still available. Unfortunately, this causes a memory leak in the case
where a mount is attempted with the test_dummy_encryption mount option,
but the mount fails after the option has already been processed.
To fix this, attempt the keyring destruction in both places.
Reported-by: syzbot+104c2a89561289cec13e@syzkaller.appspotmail.com
Fixes: d7e7b9af10 ("fscrypt: stop using keyrings subsystem for fscrypt_master_key")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20221011213838.209879-1-ebiggers@kernel.org
Make statx() support reporting direct I/O (DIO) alignment information.
This provides a generic interface for userspace programs to determine
whether a file supports DIO, and if so with what alignment restrictions.
Specifically, STATX_DIOALIGN works on block devices, and on regular
files when their containing filesystem has implemented support.
An interface like this has been requested for years, since the
conditions for when DIO is supported in Linux have gotten increasingly
complex over time. Today, DIO support and alignment requirements can be
affected by various filesystem features such as multi-device support,
data journalling, inline data, encryption, verity, compression,
checkpoint disabling, log-structured mode, etc. Further complicating
things, Linux v6.0 relaxed the traditional rule of DIO needing to be
aligned to the block device's logical block size; now user buffers (but
not file offsets) only need to be aligned to the DMA alignment.
The approach of uplifting the XFS specific ioctl XFS_IOC_DIOINFO was
discarded in favor of creating a clean new interface with statx().
For more information, see the individual commits and the man page update
https://lore.kernel.org/r/20220722074229.148925-1-ebiggers@kernel.org.
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Merge tag 'statx-dioalign-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux
Pull STATX_DIOALIGN support from Eric Biggers:
"Make statx() support reporting direct I/O (DIO) alignment information.
This provides a generic interface for userspace programs to determine
whether a file supports DIO, and if so with what alignment
restrictions. Specifically, STATX_DIOALIGN works on block devices, and
on regular files when their containing filesystem has implemented
support.
An interface like this has been requested for years, since the
conditions for when DIO is supported in Linux have gotten increasingly
complex over time. Today, DIO support and alignment requirements can
be affected by various filesystem features such as multi-device
support, data journalling, inline data, encryption, verity,
compression, checkpoint disabling, log-structured mode, etc.
Further complicating things, Linux v6.0 relaxed the traditional rule
of DIO needing to be aligned to the block device's logical block size;
now user buffers (but not file offsets) only need to be aligned to the
DMA alignment.
The approach of uplifting the XFS specific ioctl XFS_IOC_DIOINFO was
discarded in favor of creating a clean new interface with statx().
For more information, see the individual commits and the man page
update[1]"
Link: https://lore.kernel.org/r/20220722074229.148925-1-ebiggers@kernel.org [1]
* tag 'statx-dioalign-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux:
xfs: support STATX_DIOALIGN
f2fs: support STATX_DIOALIGN
f2fs: simplify f2fs_force_buffered_io()
f2fs: move f2fs_force_buffered_io() into file.c
ext4: support STATX_DIOALIGN
fscrypt: change fscrypt_dio_supported() to prepare for STATX_DIOALIGN
vfs: support STATX_DIOALIGN on block devices
statx: add direct I/O alignment information
request_queues are a block layer implementation detail that should not
leak into file systems. Change the fscrypt inline crypto code to
retrieve block devices instead of request_queues from the file system.
As part of that, clean up the interaction with multi-device file systems
by returning both the number of devices and the actual device array in a
single method call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[ebiggers: bug fixes and minor tweaks]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220901193208.138056-4-ebiggers@kernel.org
The approach of fs/crypto/ internally managing the fscrypt_master_key
structs as the payloads of "struct key" objects contained in a
"struct key" keyring has outlived its usefulness. The original idea was
to simplify the code by reusing code from the keyrings subsystem.
However, several issues have arisen that can't easily be resolved:
- When a master key struct is destroyed, blk_crypto_evict_key() must be
called on any per-mode keys embedded in it. (This started being the
case when inline encryption support was added.) Yet, the keyrings
subsystem can arbitrarily delay the destruction of keys, even past the
time the filesystem was unmounted. Therefore, currently there is no
easy way to call blk_crypto_evict_key() when a master key is
destroyed. Currently, this is worked around by holding an extra
reference to the filesystem's request_queue(s). But it was overlooked
that the request_queue reference is *not* guaranteed to pin the
corresponding blk_crypto_profile too; for device-mapper devices that
support inline crypto, it doesn't. This can cause a use-after-free.
- When the last inode that was using an incompletely-removed master key
is evicted, the master key removal is completed by removing the key
struct from the keyring. Currently this is done via key_invalidate().
Yet, key_invalidate() takes the key semaphore. This can deadlock when
called from the shrinker, since in fscrypt_ioctl_add_key(), memory is
allocated with GFP_KERNEL under the same semaphore.
- More generally, the fact that the keyrings subsystem can arbitrarily
delay the destruction of keys (via garbage collection delay, or via
random processes getting temporary key references) is undesirable, as
it means we can't strictly guarantee that all secrets are ever wiped.
- Doing the master key lookups via the keyrings subsystem results in the
key_permission LSM hook being called. fscrypt doesn't want this, as
all access control for encrypted files is designed to happen via the
files themselves, like any other files. The workaround which SELinux
users are using is to change their SELinux policy to grant key search
access to all domains. This works, but it is an odd extra step that
shouldn't really have to be done.
The fix for all these issues is to change the implementation to what I
should have done originally: don't use the keyrings subsystem to keep
track of the filesystem's fscrypt_master_key structs. Instead, just
store them in a regular kernel data structure, and rework the reference
counting, locking, and lifetime accordingly. Retain support for
RCU-mode key lookups by using a hash table. Replace fscrypt_sb_free()
with fscrypt_sb_delete(), which releases the keys synchronously and runs
a bit earlier during unmount, so that block devices are still available.
A side effect of this patch is that neither the master keys themselves
nor the filesystem keyrings will be listed in /proc/keys anymore.
("Master key users" and the master key users keyrings will still be
listed.) However, this was mostly an implementation detail, and it was
intended just for debugging purposes. I don't know of anyone using it.
This patch does *not* change how "master key users" (->mk_users) works;
that still uses the keyrings subsystem. That is still needed for key
quotas, and changing that isn't necessary to solve the issues listed
above. If we decide to change that too, it would be a separate patch.
I've marked this as fixing the original commit that added the fscrypt
keyring, but as noted above the most important issue that this patch
fixes wasn't introduced until the addition of inline encryption support.
Fixes: 22d94f493b ("fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220901193208.138056-2-ebiggers@kernel.org
To prepare for STATX_DIOALIGN support, make two changes to
fscrypt_dio_supported().
First, remove the filesystem-block-alignment check and make the
filesystems handle it instead. It previously made sense to have it in
fs/crypto/; however, to support STATX_DIOALIGN the alignment restriction
would have to be returned to filesystems. It ends up being simpler if
filesystems handle this part themselves, especially for f2fs which only
allows fs-block-aligned DIO in the first place.
Second, make fscrypt_dio_supported() work on inodes whose encryption key
hasn't been set up yet, by making it set up the key if needed. This is
required for statx(), since statx() doesn't require a file descriptor.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220827065851.135710-4-ebiggers@kernel.org
As a step towards freeing the PG_error flag for other uses, change ext4
and f2fs to stop using PG_error to track decryption errors. Instead, if
a decryption error occurs, just mark the whole bio as failed. The
coarser granularity isn't really a problem since it isn't any worse than
what the block layer provides, and errors from a multi-page readahead
aren't reported to applications unless a single-page read fails too.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <chao@kernel.org> # for f2fs part
Link: https://lore.kernel.org/r/20220815235052.86545-2-ebiggers@kernel.org
Now that all its callers have been converted to
fscrypt_parse_test_dummy_encryption() and fscrypt_add_test_dummy_key()
instead, fscrypt_set_test_dummy_encryption() can be removed.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220513231605.175121-6-ebiggers@kernel.org
Most filesystems just call fscrypt_set_context on new inodes, which
usually causes a setxattr. That's a bit late for ceph, which can send
along a full set of attributes with the create request.
Doing so allows it to avoid race windows that where the new inode could
be seen by other clients without the crypto context attached. It also
avoids the separate round trip to the server.
Refactor the fscrypt code a bit to allow us to create a new crypto
context, attach it to the inode, and write it to the buffer, but without
calling set_context on it. ceph can later use this to marshal the
context into the attributes we send along with the create request.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
For ceph, we want to use our own scheme for handling filenames that are
are longer than NAME_MAX after encryption and Base64 encoding. This
allows us to have a consistent view of the encrypted filenames for
clients that don't support fscrypt and clients that do but that don't
have the key.
Currently, fs/crypto only supports encrypting filenames using
fscrypt_setup_filename, but that also handles encoding nokey names. Ceph
can't use that because it handles nokey names in a different way.
Export fscrypt_fname_encrypt. Rename fscrypt_fname_encrypted_size to
__fscrypt_fname_encrypted_size and add a new wrapper called
fscrypt_fname_encrypted_size that takes an inode argument rather than a
pointer to a fscrypt_policy union.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Unfortunately the design of fscrypt_set_test_dummy_encryption() doesn't
work properly for the new mount API, as it combines too many steps into
one function:
- Parse the argument to test_dummy_encryption
- Check the setting against the filesystem instance
- Apply the setting to the filesystem instance
The new mount API has split these into separate steps. ext4 partially
worked around this by duplicating some of the logic, but it still had
some bugs. To address this, add some new helper functions that split up
the steps of fscrypt_set_test_dummy_encryption():
- fscrypt_parse_test_dummy_encryption()
- fscrypt_dummy_policies_equal()
- fscrypt_add_test_dummy_key()
While we're add it, also add a function fscrypt_is_dummy_policy_set()
which will be useful to avoid some #ifdef's.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220501050857.538984-5-ebiggers@kernel.org
FS_CRYPTO_BLOCK_SIZE is neither the filesystem block size nor the
granularity of encryption. Rather, it defines two logically separate
constraints that both arise from the block size of the AES cipher:
- The alignment required for the lengths of file contents blocks
- The minimum input/output length for the filenames encryption modes
Since there are way too many things called the "block size", and the
connection with the AES block size is not easily understood, split
FS_CRYPTO_BLOCK_SIZE into two constants FSCRYPT_CONTENTS_ALIGNMENT and
FSCRYPT_FNAME_MIN_MSG_LEN that more clearly describe what they are.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220405010914.18519-1-ebiggers@kernel.org
Encrypted files traditionally haven't supported DIO, due to the need to
encrypt/decrypt the data. However, when the encryption is implemented
using inline encryption (blk-crypto) instead of the traditional
filesystem-layer encryption, it is straightforward to support DIO.
In preparation for supporting this, add the following functions:
- fscrypt_dio_supported() checks whether a DIO request is supported as
far as encryption is concerned. Encrypted files will only support DIO
when inline encryption is used and the I/O request is properly
aligned; this function checks these preconditions.
- fscrypt_limit_io_blocks() limits the length of a bio to avoid crossing
a place in the file that a bio with an encryption context cannot
cross due to a DUN discontiguity. This function is needed by
filesystems that use the iomap DIO implementation (which operates
directly on logical ranges, so it won't use fscrypt_mergeable_bio())
and that support FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32.
Co-developed-by: Satya Tangirala <satyat@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220128233940.79464-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
The max_namelen field is unnecessary, as it is set to 255 (NAME_MAX) on
all filesystems that support fscrypt (or plan to support fscrypt). For
simplicity, just use NAME_MAX directly instead.
Link: https://lore.kernel.org/r/20210909184513.139281-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add a helper function fscrypt_symlink_getattr() which will be called
from the various filesystems' ->getattr() methods to read and decrypt
the target of encrypted symlinks in order to report the correct st_size.
Detailed explanation:
As required by POSIX and as documented in various man pages, st_size for
a symlink is supposed to be the length of the symlink target.
Unfortunately, st_size has always been wrong for encrypted symlinks
because st_size is populated from i_size from disk, which intentionally
contains the length of the encrypted symlink target. That's slightly
greater than the length of the decrypted symlink target (which is the
symlink target that userspace usually sees), and usually won't match the
length of the no-key encoded symlink target either.
This hadn't been fixed yet because reporting the correct st_size would
require reading the symlink target from disk and decrypting or encoding
it, which historically has been considered too heavyweight to do in
->getattr(). Also historically, the wrong st_size had only broken a
test (LTP lstat03) and there were no known complaints from real users.
(This is probably because the st_size of symlinks isn't used too often,
and when it is, typically it's for a hint for what buffer size to pass
to readlink() -- which a slightly-too-large size still works for.)
However, a couple things have changed now. First, there have recently
been complaints about the current behavior from real users:
- Breakage in rpmbuild:
https://github.com/rpm-software-management/rpm/issues/1682https://github.com/google/fscrypt/issues/305
- Breakage in toybox cpio:
https://www.mail-archive.com/toybox@lists.landley.net/msg07193.html
- Breakage in libgit2: https://issuetracker.google.com/issues/189629152
(on Android public issue tracker, requires login)
Second, we now cache decrypted symlink targets in ->i_link. Therefore,
taking the performance hit of reading and decrypting the symlink target
in ->getattr() wouldn't be as big a deal as it used to be, since usually
it will just save having to do the same thing later.
Also note that eCryptfs ended up having to read and decrypt symlink
targets in ->getattr() as well, to fix this same issue; see
commit 3a60a1686f ("eCryptfs: Decrypt symlink target for stat size").
So, let's just bite the bullet, and read and decrypt the symlink target
in ->getattr() in order to report the correct st_size. Add a function
fscrypt_symlink_getattr() which the filesystems will call to do this.
(Alternatively, we could store the decrypted size of symlinks on-disk.
But there isn't a great place to do so, and encryption is meant to hide
the original size to some extent; that property would be lost.)
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
In this round, we've made more work into per-file compression support. For
example, F2FS_IOC_GET|SET_COMPRESS_OPTION provides a way to change the
algorithm or cluster size per file. F2FS_IOC_COMPRESS|DECOMPRESS_FILE provides
a way to compress and decompress the existing normal files manually along with
a new mount option, compress_mode=fs|user, which can control who compresses the
data. Chao also added a checksum feature with a mount option so that we are able
to detect any corrupted cluster. In addition, Daniel contributed casefolding
with encryption patch, which will be used for Android devices.
Enhancement:
- add ioctls and mount option to manage per-file compression feature
- support casefolding with encryption
- support checksum for compressed cluster
- avoid IO starvation by replacing mutex with rwsem
- add sysfs, max_io_bytes, to control max bio size
Bug fix:
- fix use-after-free issue when compression and fsverity are enabled
- fix consistency corruption during fault injection test
- fix data offset for lseek
- get rid of buffer_head which has 32bits limit in fiemap
- fix some bugs in multi-partitions support
- fix nat entry count calculation in shrinker
- fix some stat information
And, we've refactored some logics and fix minor bugs as well.
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Merge tag 'f2fs-for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
"In this round, we've made more work into per-file compression support.
For example, F2FS_IOC_GET | SET_COMPRESS_OPTION provides a way to
change the algorithm or cluster size per file. F2FS_IOC_COMPRESS |
DECOMPRESS_FILE provides a way to compress and decompress the existing
normal files manually.
There is also a new mount option, compress_mode=fs|user, which can
control who compresses the data.
Chao also added a checksum feature with a mount option so that
we are able to detect any corrupted cluster.
In addition, Daniel contributed casefolding with encryption patch,
which will be used for Android devices.
Summary:
Enhancements:
- add ioctls and mount option to manage per-file compression feature
- support casefolding with encryption
- support checksum for compressed cluster
- avoid IO starvation by replacing mutex with rwsem
- add sysfs, max_io_bytes, to control max bio size
Bug fixes:
- fix use-after-free issue when compression and fsverity are enabled
- fix consistency corruption during fault injection test
- fix data offset for lseek
- get rid of buffer_head which has 32bits limit in fiemap
- fix some bugs in multi-partitions support
- fix nat entry count calculation in shrinker
- fix some stat information
And, we've refactored some logics and fix minor bugs as well"
* tag 'f2fs-for-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (36 commits)
f2fs: compress: fix compression chksum
f2fs: fix shift-out-of-bounds in sanity_check_raw_super()
f2fs: fix race of pending_pages in decompression
f2fs: fix to account inline xattr correctly during recovery
f2fs: inline: fix wrong inline inode stat
f2fs: inline: correct comment in f2fs_recover_inline_data
f2fs: don't check PAGE_SIZE again in sanity_check_raw_super()
f2fs: convert to F2FS_*_INO macro
f2fs: introduce max_io_bytes, a sysfs entry, to limit bio size
f2fs: don't allow any writes on readonly mount
f2fs: avoid race condition for shrinker count
f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE
f2fs: add compress_mode mount option
f2fs: Remove unnecessary unlikely()
f2fs: init dirty_secmap incorrectly
f2fs: remove buffer_head which has 32bits limit
f2fs: fix wrong block count instead of bytes
f2fs: use new conversion functions between blks and bytes
f2fs: rename logical_to_blk and blk_to_logical
f2fs: fix kbytes written stat for multi-device case
...
This shifts the responsibility of setting up dentry operations from
fscrypt to the individual filesystems, allowing them to have their own
operations while still setting fscrypt's d_revalidate as appropriate.
Most filesystems can just use generic_set_encrypted_ci_d_ops, unless
they have their own specific dentry operations as well. That operation
will set the minimal d_ops required under the circumstances.
Since the fscrypt d_ops are set later on, we must set all d_ops there,
since we cannot adjust those later on. This should not result in any
change in behavior.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Currently it's impossible to delete files that use an unsupported
encryption policy, as the kernel will just return an error when
performing any operation on the top-level encrypted directory, even just
a path lookup into the directory or opening the directory for readdir.
More specifically, this occurs in any of the following cases:
- The encryption context has an unrecognized version number. Current
kernels know about v1 and v2, but there could be more versions in the
future.
- The encryption context has unrecognized encryption modes
(FSCRYPT_MODE_*) or flags (FSCRYPT_POLICY_FLAG_*), an unrecognized
combination of modes, or reserved bits set.
- The encryption key has been added and the encryption modes are
recognized but aren't available in the crypto API -- for example, a
directory is encrypted with FSCRYPT_MODE_ADIANTUM but the kernel
doesn't have CONFIG_CRYPTO_ADIANTUM enabled.
It's desirable to return errors for most operations on files that use an
unsupported encryption policy, but the current behavior is too strict.
We need to allow enough to delete files, so that people can't be stuck
with undeletable files when downgrading kernel versions. That includes
allowing directories to be listed and allowing dentries to be looked up.
Fix this by modifying the key setup logic to treat an unsupported
encryption policy in the same way as "key unavailable" in the cases that
are required for a recursive delete to work: preparing for a readdir or
a dentry lookup, revalidating a dentry, or checking whether an inode has
the same encryption policy as its parent directory.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201203022041.230976-10-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Now that fscrypt_get_encryption_info() is only called from files in
fs/crypto/ (due to all key setup now being handled by higher-level
helper functions instead of directly by filesystems), unexport it and
move its declaration to fscrypt_private.h.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201203022041.230976-9-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
fscrypt_require_key() is now only used by files in fs/crypto/. So
reduce its visibility to fscrypt_private.h. This is also a prerequsite
for unexporting fscrypt_get_encryption_info().
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201203022041.230976-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
In preparation for reducing the visibility of fscrypt_require_key() by
moving it to fscrypt_private.h, move the call to it from
fscrypt_prepare_setattr() to an out-of-line function.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201203022041.230976-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
The last remaining use of fscrypt_get_encryption_info() from filesystems
is for readdir (->iterate_shared()). Every other call is now in
fs/crypto/ as part of some other higher-level operation.
We need to add a new argument to fscrypt_get_encryption_info() to
indicate whether the encryption policy is allowed to be unrecognized or
not. Doing this is easier if we can work with high-level operations
rather than direct filesystem use of fscrypt_get_encryption_info().
So add a function fscrypt_prepare_readdir() which wraps the call to
fscrypt_get_encryption_info() for the readdir use case.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201203022041.230976-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
In an encrypted directory, a regular dentry (one that doesn't have the
no-key name flag) can only be created if the directory's encryption key
is available.
Therefore the calls to fscrypt_require_key() in __fscrypt_prepare_link()
and __fscrypt_prepare_rename() are unnecessary, as these functions
already check that the dentries they're given aren't no-key names.
Remove these unnecessary calls to fscrypt_require_key().
Link: https://lore.kernel.org/r/20201118075609.120337-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
It's possible to create a duplicate filename in an encrypted directory
by creating a file concurrently with adding the encryption key.
Specifically, sys_open(O_CREAT) (or sys_mkdir(), sys_mknod(), or
sys_symlink()) can lookup the target filename while the directory's
encryption key hasn't been added yet, resulting in a negative no-key
dentry. The VFS then calls ->create() (or ->mkdir(), ->mknod(), or
->symlink()) because the dentry is negative. Normally, ->create() would
return -ENOKEY due to the directory's key being unavailable. However,
if the key was added between the dentry lookup and ->create(), then the
filesystem will go ahead and try to create the file.
If the target filename happens to already exist as a normal name (not a
no-key name), a duplicate filename may be added to the directory.
In order to fix this, we need to fix the filesystems to prevent
->create(), ->mkdir(), ->mknod(), and ->symlink() on no-key names.
(->rename() and ->link() need it too, but those are already handled
correctly by fscrypt_prepare_rename() and fscrypt_prepare_link().)
In preparation for this, add a helper function fscrypt_is_nokey_name()
that filesystems can use to do this check. Use this helper function for
the existing checks that fs/crypto/ does for rename and link.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201118075609.120337-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Dentries that represent no-key names must have a dentry_operations that
includes fscrypt_d_revalidate(). Currently, this is handled by
fscrypt_prepare_lookup() installing fscrypt_d_ops.
However, ceph support for encryption
(https://lore.kernel.org/r/20200914191707.380444-1-jlayton@kernel.org)
can't use fscrypt_d_ops, since ceph already has its own
dentry_operations.
Similarly, ext4 and f2fs support for directories that are both encrypted
and casefolded
(https://lore.kernel.org/r/20200923010151.69506-1-drosen@google.com)
can't use fscrypt_d_ops either, since casefolding requires some dentry
operations too.
To satisfy both users, we need to move the responsibility of installing
the dentry_operations to filesystems.
In preparation for this, export fscrypt_d_revalidate() and give it a
!CONFIG_FS_ENCRYPTION stub.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200924054721.187797-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Originally we used the term "encrypted name" or "ciphertext name" to
mean the encoded filename that is shown when an encrypted directory is
listed without its key. But these terms are ambiguous since they also
mean the filename stored on-disk. "Encrypted name" is especially
ambiguous since it could also be understood to mean "this filename is
encrypted on-disk", similar to "encrypted file".
So we've started calling these encoded names "no-key names" instead.
Therefore, rename DCACHE_ENCRYPTED_NAME to DCACHE_NOKEY_NAME to avoid
confusion about what this flag means.
Link: https://lore.kernel.org/r/20200924042624.98439-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Currently we're using the term "ciphertext name" ambiguously because it
can mean either the actual ciphertext filename, or the encoded filename
that is shown when an encrypted directory is listed without its key.
The latter we're now usually calling the "no-key name"; and while it's
derived from the ciphertext name, it's not the same thing.
To avoid this ambiguity, rename fscrypt_name::is_ciphertext_name to
fscrypt_name::is_nokey_name, and update comments that say "ciphertext
name" (or "encrypted name") to say "no-key name" instead when warranted.
Link: https://lore.kernel.org/r/20200924042624.98439-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
fscrypt_set_test_dummy_encryption() requires that the optional argument
to the test_dummy_encryption mount option be specified as a substring_t.
That doesn't work well with filesystems that use the new mount API,
since the new way of parsing mount options doesn't use substring_t.
Make it take the argument as a 'const char *' instead.
Instead of moving the match_strdup() into the callers in ext4 and f2fs,
make them just use arg->from directly. Since the pattern is
"test_dummy_encryption=%s", the argument will be null-terminated.
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-14-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
The behavior of the test_dummy_encryption mount option is that when a
new file (or directory or symlink) is created in an unencrypted
directory, it's automatically encrypted using a dummy encryption policy.
That's it; in particular, the encryption (or lack thereof) of existing
files (or directories or symlinks) doesn't change.
Unfortunately the implementation of test_dummy_encryption is a bit weird
and confusing. When test_dummy_encryption is enabled and a file is
being created in an unencrypted directory, we set up an encryption key
(->i_crypt_info) for the directory. This isn't actually used to do any
encryption, however, since the directory is still unencrypted! Instead,
->i_crypt_info is only used for inheriting the encryption policy.
One consequence of this is that the filesystem ends up providing a
"dummy context" (policy + nonce) instead of a "dummy policy". In
commit ed318a6cc0 ("fscrypt: support test_dummy_encryption=v2"), I
mistakenly thought this was required. However, actually the nonce only
ends up being used to derive a key that is never used.
Another consequence of this implementation is that it allows for
'inode->i_crypt_info != NULL && !IS_ENCRYPTED(inode)', which is an edge
case that can be forgotten about. For example, currently
FS_IOC_GET_ENCRYPTION_POLICY on an unencrypted directory may return the
dummy encryption policy when the filesystem is mounted with
test_dummy_encryption. That seems like the wrong thing to do, since
again, the directory itself is not actually encrypted.
Therefore, switch to a more logical and maintainable implementation
where the dummy encryption policy inheritance is done without setting up
keys for unencrypted directories. This involves:
- Adding a function fscrypt_policy_to_inherit() which returns the
encryption policy to inherit from a directory. This can be a real
policy, a dummy policy, or no policy.
- Replacing struct fscrypt_dummy_context, ->get_dummy_context(), etc.
with struct fscrypt_dummy_policy, ->get_dummy_policy(), etc.
- Making fscrypt_fname_encrypted_size() take an fscrypt_policy instead
of an inode.
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-13-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
In preparation for moving the logic for "get the encryption policy
inherited by new files in this directory" to a single place, make
fscrypt_prepare_symlink() a regular function rather than an inline
function that wraps __fscrypt_prepare_symlink().
This way, the new function fscrypt_policy_to_inherit() won't need to be
exported to filesystems.
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-12-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Now that all filesystems have been converted to use
fscrypt_prepare_new_inode() and fscrypt_set_context(),
fscrypt_inherit_context() is no longer used. Remove it.
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
fscrypt_get_encryption_info() is intended to be GFP_NOFS-safe. But
actually it isn't, since it uses functions like crypto_alloc_skcipher()
which aren't GFP_NOFS-safe, even when called under memalloc_nofs_save().
Therefore it can deadlock when called from a context that needs
GFP_NOFS, e.g. during an ext4 transaction or between f2fs_lock_op() and
f2fs_unlock_op(). This happens when creating a new encrypted file.
We can't fix this by just not setting up the key for new inodes right
away, since new symlinks need their key to encrypt the symlink target.
So we need to set up the new inode's key before starting the
transaction. But just calling fscrypt_get_encryption_info() earlier
doesn't work, since it assumes the encryption context is already set,
and the encryption context can't be set until the transaction.
The recently proposed fscrypt support for the ceph filesystem
(https://lkml.kernel.org/linux-fscrypt/20200821182813.52570-1-jlayton@kernel.org/T/#u)
will have this same ordering problem too, since ceph will need to
encrypt new symlinks before setting their encryption context.
Finally, f2fs can deadlock when the filesystem is mounted with
'-o test_dummy_encryption' and a new file is created in an existing
unencrypted directory. Similarly, this is caused by holding too many
locks when calling fscrypt_get_encryption_info().
To solve all these problems, add new helper functions:
- fscrypt_prepare_new_inode() sets up a new inode's encryption key
(fscrypt_info), using the parent directory's encryption policy and a
new random nonce. It neither reads nor writes the encryption context.
- fscrypt_set_context() persists the encryption context of a new inode,
using the information from the fscrypt_info already in memory. This
replaces fscrypt_inherit_context().
Temporarily keep fscrypt_inherit_context() around until all filesystems
have been converted to use fscrypt_set_context().
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Normally smp_store_release() or cmpxchg_release() is paired with
smp_load_acquire(). Sometimes smp_load_acquire() can be replaced with
the more lightweight READ_ONCE(). However, for this to be safe, all the
published memory must only be accessed in a way that involves the
pointer itself. This may not be the case if allocating the object also
involves initializing a static or global variable, for example.
fscrypt_info includes various sub-objects which are internal to and are
allocated by other kernel subsystems such as keyrings and crypto. So by
using READ_ONCE() for ->i_crypt_info, we're relying on internal
implementation details of these other kernel subsystems.
Remove this fragile assumption by using smp_load_acquire() instead.
(Note: I haven't seen any real-world problems here. This change is just
fixing the code to be guaranteed correct and less fragile.)
Fixes: e37a784d8b ("fscrypt: use READ_ONCE() to access ->i_crypt_info")
Link: https://lore.kernel.org/r/20200721225920.114347-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add support for inline encryption to fs/crypto/. With "inline
encryption", the block layer handles the decryption/encryption as part
of the bio, instead of the filesystem doing the crypto itself via
Linux's crypto API. This model is needed in order to take advantage of
the inline encryption hardware present on most modern mobile SoCs.
To use inline encryption, the filesystem needs to be mounted with
'-o inlinecrypt'. Blk-crypto will then be used instead of the traditional
filesystem-layer crypto whenever possible to encrypt the contents
of any encrypted files in that filesystem. Fscrypt still provides the key
and IV to use, and the actual ciphertext on-disk is still the same;
therefore it's testable using the existing fscrypt ciphertext verification
tests.
Note that since blk-crypto has a fallback to Linux's crypto API, and
also supports all the encryption modes currently supported by fscrypt,
this feature is usable and testable even without actual inline
encryption hardware.
Per-filesystem changes will be needed to set encryption contexts when
submitting bios and to implement the 'inlinecrypt' mount option. This
patch just adds the common code.
Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200702015607.1215430-3-satyat@google.com
Co-developed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
v1 encryption policies are deprecated in favor of v2, and some new
features (e.g. encryption+casefolding) are only being added for v2.
Therefore, the "test_dummy_encryption" mount option (which is used for
encryption I/O testing with xfstests) needs to support v2 policies.
To do this, extend its syntax to be "test_dummy_encryption=v1" or
"test_dummy_encryption=v2". The existing "test_dummy_encryption" (no
argument) also continues to be accepted, to specify the default setting
-- currently v1, but the next patch changes it to v2.
To cleanly support both v1 and v2 while also making it easy to support
specifying other encryption settings in the future (say, accepting
"$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
pointer to the dummy fscrypt_context rather than using mount flags.
To avoid concurrency issues, don't allow test_dummy_encryption to be set
or changed during a remount. (The former restriction is new, but
xfstests doesn't run into it, so no one should notice.)
Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'. On ext4,
there are two regressions, both of which are test bugs: ext4/023 and
ext4/028 fail because they set an xattr and expect it to be stored
inline, but the increase in size of the fscrypt_context from
24 to 40 bytes causes this xattr to be spilled into an external block.
Link: https://lore.kernel.org/r/20200512233251.118314-4-ebiggers@kernel.org
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Gabriel Krisman Bertazi