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
Now that the fscrypt_master_key lifetime has been reworked to not be
subject to the quirks of the keyrings subsystem, blk_crypto_evict_key()
no longer gets called after the filesystem has already been unmounted.
Therefore, there is no longer any need to hold extra references to the
filesystem's request_queue(s). (And these references didn't always do
their intended job anyway, as pinning a request_queue doesn't
necessarily pin the corresponding blk_crypto_profile.)
Stop taking these extra references. Instead, just pass the super_block
to fscrypt_destroy_inline_crypt_key(), and use it to get the list of
block devices the key needs to be evicted from.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220901193208.138056-3-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
Luis and others, almost exclusively in the filesystem. Several patches
touch files outside of our normal purview to set the stage for bringing
in Jeff's long awaited ceph+fscrypt series in the near future. All of
them have appropriate acks and sat in linux-next for a while.
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Merge tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client
Pull ceph updates from Ilya Dryomov:
"We have a good pile of various fixes and cleanups from Xiubo, Jeff,
Luis and others, almost exclusively in the filesystem.
Several patches touch files outside of our normal purview to set the
stage for bringing in Jeff's long awaited ceph+fscrypt series in the
near future. All of them have appropriate acks and sat in linux-next
for a while"
* tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client: (27 commits)
libceph: clean up ceph_osdc_start_request prototype
libceph: fix ceph_pagelist_reserve() comment typo
ceph: remove useless check for the folio
ceph: don't truncate file in atomic_open
ceph: make f_bsize always equal to f_frsize
ceph: flush the dirty caps immediatelly when quota is approaching
libceph: print fsid and epoch with osd id
libceph: check pointer before assigned to "c->rules[]"
ceph: don't get the inline data for new creating files
ceph: update the auth cap when the async create req is forwarded
ceph: make change_auth_cap_ses a global symbol
ceph: fix incorrect old_size length in ceph_mds_request_args
ceph: switch back to testing for NULL folio->private in ceph_dirty_folio
ceph: call netfs_subreq_terminated with was_async == false
ceph: convert to generic_file_llseek
ceph: fix the incorrect comment for the ceph_mds_caps struct
ceph: don't leak snap_rwsem in handle_cap_grant
ceph: prevent a client from exceeding the MDS maximum xattr size
ceph: choose auth MDS for getxattr with the Xs caps
ceph: add session already open notify support
...
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>
HCTR2 is a tweakable, length-preserving encryption mode that is intended
for use on CPUs with dedicated crypto instructions. HCTR2 has the
property that a bitflip in the plaintext changes the entire ciphertext.
This property fixes a known weakness with filename encryption: when two
filenames in the same directory share a prefix of >= 16 bytes, with
AES-CTS-CBC their encrypted filenames share a common substring, leaking
information. HCTR2 does not have this problem.
More information on HCTR2 can be found here: "Length-preserving
encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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
Factor out a function that builds the fscrypt_key_specifier for an
fscrypt_policy. Before this was only needed when finding the key for a
file, but now it will also be needed for test_dummy_encryption support.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220501050857.538984-4-ebiggers@kernel.org
When inline encryption is used, the usual message "fscrypt: AES-256-XTS
using implementation <impl>" doesn't appear in the kernel log. Add a
similar message for the blk-crypto case that indicates that inline
encryption was used, and whether blk-crypto-fallback was used or not.
This can be useful for debugging performance problems.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220414053415.158986-1-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
All filesystems have now been converted to use ->readahead, so
remove the ->readpages operation and fix all the comments that
used to refer to it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Add support for direct I/O on encrypted files when blk-crypto (inline
encryption) is being used for file contents encryption.
There will be a merge conflict with the block pull request in
fs/iomap/direct-io.c, due to some bio interface cleanups. The merge
resolution is straightforward and can be found in linux-next.
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Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt
Pull fscrypt updates from Eric Biggers:
"Add support for direct I/O on encrypted files when blk-crypto (inline
encryption) is being used for file contents encryption"
* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
fscrypt: update documentation for direct I/O support
f2fs: support direct I/O with fscrypt using blk-crypto
ext4: support direct I/O with fscrypt using blk-crypto
iomap: support direct I/O with fscrypt using blk-crypto
fscrypt: add functions for direct I/O support
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>
Pass the block_device that we plan to use this bio for and the
operation to bio_reset to optimize the assigment. A NULL block_device
can be passed, both for the passthrough case on a raw request_queue and
to temporarily avoid refactoring some nasty code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-20-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the block_device and operation that we plan to use this bio for to
bio_alloc to optimize the assignment. NULL/0 can be passed, both for the
passthrough case on a raw request_queue and to temporarily avoid
refactoring some nasty code.
Also move the gfp_mask argument after the nr_vecs argument for a much
more logical calling convention matching what most of the kernel does.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
fscrypt currently requires a 512-bit master key when AES-256-XTS is
used, since AES-256-XTS keys are 512-bit and fscrypt requires that the
master key be at least as long any key that will be derived from it.
However, this is overly strict because AES-256-XTS doesn't actually have
a 512-bit security strength, but rather 256-bit. The fact that XTS
takes twice the expected key size is a quirk of the XTS mode. It is
sufficient to use 256 bits of entropy for AES-256-XTS, provided that it
is first properly expanded into a 512-bit key, which HKDF-SHA512 does.
Therefore, relax the check of the master key size to use the security
strength of the derived key rather than the size of the derived key
(except for v1 encryption policies, which don't use HKDF).
Besides making things more flexible for userspace, this is needed in
order for the use of a KDF which only takes a 256-bit key to be
introduced into the fscrypt key hierarchy. This will happen with
hardware-wrapped keys support, as all known hardware which supports that
feature uses an SP800-108 KDF using AES-256-CMAC, so the wrapped keys
are wrapped 256-bit AES keys. Moreover, there is interest in fscrypt
supporting the same type of AES-256-CMAC based KDF in software as an
alternative to HKDF-SHA512. There is no security problem with such
features, so fix the key length check to work properly with them.
Reviewed-by: Paul Crowley <paulcrowley@google.com>
Link: https://lore.kernel.org/r/20210921030303.5598-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
The file comment in bio.c is almost completely irrelevant to the actual
contents of the file; it was originally copied from crypto.c. Fix it
up, and also add a kerneldoc comment for fscrypt_decrypt_bio().
Link: https://lore.kernel.org/r/20210909190737.140841-1-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>
fscrypt uses a Base64 encoding to encode no-key filenames (the filenames
that are presented to userspace when a directory is listed without its
encryption key). There are many variants of Base64, but the most common
ones are specified by RFC 4648. fscrypt can't use the regular RFC 4648
"base64" variant because "base64" uses the '/' character, which isn't
allowed in filenames. However, RFC 4648 also specifies a "base64url"
variant for use in URLs and filenames. "base64url" is less common than
"base64", but it's still implemented in many programming libraries.
Unfortunately, what fscrypt actually uses is a custom Base64 variant
that differs from "base64url" in several ways:
- The binary data is divided into 6-bit chunks differently.
- Values 62 and 63 are encoded with '+' and ',' instead of '-' and '_'.
- '='-padding isn't used. This isn't a problem per se, as the padding
isn't technically necessary, and RFC 4648 doesn't strictly require it.
But it needs to be properly documented.
There have been two attempts to copy the fscrypt Base64 code into lib/
(https://lkml.kernel.org/r/20200821182813.52570-6-jlayton@kernel.org and
https://lkml.kernel.org/r/20210716110428.9727-5-hare@suse.de), and both
have been caught up by the fscrypt Base64 variant being nonstandard and
not properly documented. Also, the planned use of the fscrypt Base64
code in the CephFS storage back-end will prevent it from being changed
later (whereas currently it can still be changed), so we need to choose
an encoding that we're happy with before it's too late.
Therefore, switch the fscrypt Base64 variant to base64url, in order to
align more closely with RFC 4648 and other implementations and uses of
Base64. However, I opted not to implement '='-padding, as '='-padding
adds complexity, is unnecessary, and isn't required by the RFC.
Link: https://lore.kernel.org/r/20210718000125.59701-1-ebiggers@kernel.org
Reviewed-by: Hannes Reinecke <hare@suse.de>
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>
Typically, the cryptographic APIs that fscrypt uses take keys as byte
arrays, which avoids endianness issues. However, siphash_key_t is an
exception. It is defined as 'u64 key[2];', i.e. the 128-bit key is
expected to be given directly as two 64-bit words in CPU endianness.
fscrypt_derive_dirhash_key() and fscrypt_setup_iv_ino_lblk_32_key()
forgot to take this into account. Therefore, the SipHash keys used to
index encrypted+casefolded directories differ on big endian vs. little
endian platforms, as do the SipHash keys used to hash inode numbers for
IV_INO_LBLK_32-encrypted directories. This makes such directories
non-portable between these platforms.
Fix this by always using the little endian order. This is a breaking
change for big endian platforms, but this should be fine in practice
since these features (encrypt+casefold support, and the IV_INO_LBLK_32
flag) aren't known to actually be used on any big endian platforms yet.
Fixes: aa408f835d ("fscrypt: derive dirhash key for casefolded directories")
Fixes: e3b1078bed ("fscrypt: add support for IV_INO_LBLK_32 policies")
Cc: <stable@vger.kernel.org> # v5.6+
Link: https://lore.kernel.org/r/20210605075033.54424-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
When initializing a no-key name, fscrypt_fname_disk_to_usr() sets the
minor_hash to 0 if the (major) hash is 0.
This doesn't make sense because 0 is a valid hash code, so we shouldn't
ignore the filesystem-provided minor_hash in that case. Fix this by
removing the special case for 'hash == 0'.
This is an old bug that appears to have originated when the encryption
code in ext4 and f2fs was moved into fs/crypto/. The original ext4 and
f2fs code passed the hash by pointer instead of by value. So
'if (hash)' actually made sense then, as it was checking whether a
pointer was NULL. But now the hashes are passed by value, and
filesystems just pass 0 for any hashes they don't have. There is no
need to handle this any differently from the hashes actually being 0.
It is difficult to reproduce this bug, as it only made a difference in
the case where a filename's 32-bit major hash happened to be 0.
However, it probably had the largest chance of causing problems on
ubifs, since ubifs uses minor_hash to do lookups of no-key names, in
addition to using it as a readdir cookie. ext4 only uses minor_hash as
a readdir cookie, and f2fs doesn't use minor_hash at all.
Fixes: 0b81d07790 ("fs crypto: move per-file encryption from f2fs tree to fs/crypto")
Cc: <stable@vger.kernel.org> # v4.6+
Link: https://lore.kernel.org/r/20210527235236.2376556-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Pull crypto updates from Herbert Xu:
"API:
- crypto_destroy_tfm now ignores errors as well as NULL pointers
Algorithms:
- Add explicit curve IDs in ECDH algorithm names
- Add NIST P384 curve parameters
- Add ECDSA
Drivers:
- Add support for Green Sardine in ccp
- Add ecdh/curve25519 to hisilicon/hpre
- Add support for AM64 in sa2ul"
* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (184 commits)
fsverity: relax build time dependency on CRYPTO_SHA256
fscrypt: relax Kconfig dependencies for crypto API algorithms
crypto: camellia - drop duplicate "depends on CRYPTO"
crypto: s5p-sss - consistently use local 'dev' variable in probe()
crypto: s5p-sss - remove unneeded local variable initialization
crypto: s5p-sss - simplify getting of_device_id match data
ccp: ccp - add support for Green Sardine
crypto: ccp - Make ccp_dev_suspend and ccp_dev_resume void functions
crypto: octeontx2 - add support for OcteonTX2 98xx CPT block.
crypto: chelsio/chcr - Remove useless MODULE_VERSION
crypto: ux500/cryp - Remove duplicate argument
crypto: chelsio - remove unused function
crypto: sa2ul - Add support for AM64
crypto: sa2ul - Support for per channel coherency
dt-bindings: crypto: ti,sa2ul: Add new compatible for AM64
crypto: hisilicon - enable new error types for QM
crypto: hisilicon - add new error type for SEC
crypto: hisilicon - support new error types for ZIP
crypto: hisilicon - dynamic configuration 'err_info'
crypto: doc - fix kernel-doc notation in chacha.c and af_alg.c
...
Even if FS encryption has strict functional dependencies on various
crypto algorithms and chaining modes. those dependencies could potentially
be satisified by other implementations than the generic ones, and no link
time dependency exists on the 'depends on' claused defined by
CONFIG_FS_ENCRYPTION_ALGS.
So let's relax these clauses to 'imply', so that the default behavior
is still to pull in those generic algorithms, but in a way that permits
them to be disabled again in Kconfig.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Ever since the addition of multipage bio_vecs BIO_MAX_PAGES has been
horribly confusingly misnamed. Rename it to BIO_MAX_VECS to stop
confusing users of the bio API.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210311110137.1132391-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.
Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.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
...
Pull crypto updates from Herbert Xu:
"API:
- Add speed testing on 1420-byte blocks for networking
Algorithms:
- Improve performance of chacha on ARM for network packets
- Improve performance of aegis128 on ARM for network packets
Drivers:
- Add support for Keem Bay OCS AES/SM4
- Add support for QAT 4xxx devices
- Enable crypto-engine retry mechanism in caam
- Enable support for crypto engine on sdm845 in qce
- Add HiSilicon PRNG driver support"
* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (161 commits)
crypto: qat - add capability detection logic in qat_4xxx
crypto: qat - add AES-XTS support for QAT GEN4 devices
crypto: qat - add AES-CTR support for QAT GEN4 devices
crypto: atmel-i2c - select CONFIG_BITREVERSE
crypto: hisilicon/trng - replace atomic_add_return()
crypto: keembay - Add support for Keem Bay OCS AES/SM4
dt-bindings: Add Keem Bay OCS AES bindings
crypto: aegis128 - avoid spurious references crypto_aegis128_update_simd
crypto: seed - remove trailing semicolon in macro definition
crypto: x86/poly1305 - Use TEST %reg,%reg instead of CMP $0,%reg
crypto: x86/sha512 - Use TEST %reg,%reg instead of CMP $0,%reg
crypto: aesni - Use TEST %reg,%reg instead of CMP $0,%reg
crypto: cpt - Fix sparse warnings in cptpf
hwrng: ks-sa - Add dependency on IOMEM and OF
crypto: lib/blake2s - Move selftest prototype into header file
crypto: arm/aes-ce - work around Cortex-A57/A72 silion errata
crypto: ecdh - avoid unaligned accesses in ecdh_set_secret()
crypto: ccree - rework cache parameters handling
crypto: cavium - Use dma_set_mask_and_coherent to simplify code
crypto: marvell/octeontx - Use dma_set_mask_and_coherent to simplify code
...
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>
The stated reasons for separating fscrypt_master_key::mk_secret_sem from
the standard semaphore contained in every 'struct key' no longer apply.
First, due to commit a992b20cd4 ("fscrypt: add
fscrypt_prepare_new_inode() and fscrypt_set_context()"),
fscrypt_get_encryption_info() is no longer called from within a
filesystem transaction.
Second, due to commit d3ec10aa95 ("KEYS: Don't write out to userspace
while holding key semaphore"), the semaphore for the "keyring" key type
no longer ranks above page faults.
That leaves performance as the only possible reason to keep the separate
mk_secret_sem. Specifically, having mk_secret_sem reduces the
contention between setup_file_encryption_key() and
FS_IOC_{ADD,REMOVE}_ENCRYPTION_KEY. However, these ioctls aren't
executed often, so this doesn't seem to be worth the extra complexity.
Therefore, simplify the locking design by just using key->sem instead of
mk_secret_sem.
Link: https://lore.kernel.org/r/20201117032626.320275-1-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>
Currently <crypto/sha.h> contains declarations for both SHA-1 and SHA-2,
and <crypto/sha3.h> contains declarations for SHA-3.
This organization is inconsistent, but more importantly SHA-1 is no
longer considered to be cryptographically secure. So to the extent
possible, SHA-1 shouldn't be grouped together with any of the other SHA
versions, and usage of it should be phased out.
Therefore, split <crypto/sha.h> into two headers <crypto/sha1.h> and
<crypto/sha2.h>, and make everyone explicitly specify whether they want
the declarations for SHA-1, SHA-2, or both.
This avoids making the SHA-1 declarations visible to files that don't
want anything to do with SHA-1. It also prepares for potentially moving
sha1.h into a new insecure/ or dangerous/ directory.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
There isn't really any valid reason to use __FSCRYPT_MODE_MAX or
FSCRYPT_POLICY_FLAGS_VALID in a userspace program. These constants are
only meant to be used by the kernel internally, and they are defined in
the UAPI header next to the mode numbers and flags only so that kernel
developers don't forget to update them when adding new modes or flags.
In https://lkml.kernel.org/r/20201005074133.1958633-2-satyat@google.com
there was an example of someone wanting to use __FSCRYPT_MODE_MAX in a
user program, and it was wrong because the program would have broken if
__FSCRYPT_MODE_MAX were ever increased. So having this definition
available is harmful. FSCRYPT_POLICY_FLAGS_VALID has the same problem.
So, remove these definitions from the UAPI header. Replace
FSCRYPT_POLICY_FLAGS_VALID with just listing the valid flags explicitly
in the one kernel function that needs it. Move __FSCRYPT_MODE_MAX to
fscrypt_private.h, remove the double underscores (which were only
present to discourage use by userspace), and add a BUILD_BUG_ON() and
comments to (hopefully) ensure it is kept in sync.
Keep the old name FS_POLICY_FLAGS_VALID, since it's been around for
longer and there's a greater chance that removing it would break source
compatibility with some program. Indeed, mtd-utils is using it in
an #ifdef, and removing it would introduce compiler warnings (about
FS_POLICY_FLAGS_PAD_* being redefined) into the mtd-utils build.
However, reduce its value to 0x07 so that it only includes the flags
with old names (the ones present before Linux 5.4), and try to make it
clear that it's now "frozen" and no new flags should be added to it.
Fixes: 2336d0deb2 ("fscrypt: use FSCRYPT_ prefix for uapi constants")
Cc: <stable@vger.kernel.org> # v5.4+
Link: https://lore.kernel.org/r/20201024005132.495952-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
The new helper function fscrypt_prepare_new_inode() runs before
S_ENCRYPTED has been set on the new inode. This accidentally made
fscrypt_select_encryption_impl() never enable inline encryption on newly
created files, due to its use of fscrypt_needs_contents_encryption()
which only returns true when S_ENCRYPTED is set.
Fix this by using S_ISREG() directly instead of
fscrypt_needs_contents_encryption(), analogous to what
select_encryption_mode() does.
I didn't notice this earlier because by design, the user-visible
behavior is the same (other than performance, potentially) regardless of
whether inline encryption is used or not.
Fixes: a992b20cd4 ("fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()")
Reviewed-by: Satya Tangirala <satyat@google.com>
Link: https://lore.kernel.org/r/20201111015224.303073-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
I_CREATING isn't actually set until the inode has been assigned an inode
number and inserted into the inode hash table. So the WARN_ON() in
fscrypt_setup_iv_ino_lblk_32_key() is wrong, and it can trigger when
creating an encrypted file on ext4. Remove it.
This was sometimes causing xfstest generic/602 to fail on ext4. I
didn't notice it before because due to a separate oversight, new inodes
that haven't been assigned an inode number yet don't necessarily have
i_ino == 0 as I had thought, so by chance I never saw the test fail.
Fixes: a992b20cd4 ("fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()")
Reported-by: Theodore Y. Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20201031004556.87862-1-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>
Linus Torvalds
Christoph Hellwig
Eric Biggers
Jeff Layton
Nathan Huckleberry
Matthew Wilcox (Oracle)
Ard Biesheuvel
Christian Brauner
Daniel Rosenberg