kernel/linux.git/fs/crypto/inline_crypt.c, branch v6.12.102

fscrypt: Avoid dynamic allocation in fscrypt_get_devices()

2026-08-03T09:17:29+00:00

commit 6fe4e4b8259e1330945b5f3c9476e08473b8e0e8 upstream. When a blk_crypto_key starts being used or is evicted, fs/crypto/ calls fscrypt_get_devices() to get the filesystem's list of block devices, then iterates over them and calls blk_crypto_config_supported(), blk_crypto_start_using_key(), or blk_crypto_evict_key() on each one. Currently, the block device pointers are placed in a dynamically allocated array. This dynamic allocation is problematic because: - It can fail, especially at the fscrypt_destroy_inline_crypt_key() call site when it's invoked for inode eviction under direct reclaim. - fscrypt_destroy_inline_crypt_key() doesn't handle the failure. It just zeroizes and frees the blk_crypto_key without calling blk_crypto_evict_key(). That causes a use-after-free. For now, let's fix this in the straightforward and easily-backportable way by switching to an on-stack array. Currently the fscrypt multi-device functionality is used only by f2fs, which has a hardcoded limit of 8 block devices. An on-stack array works fine for that. (Of course, this solution won't scale up to large number of block devices. For that we'd need a different solution, like moving the block device iteration into the filesystem. Or in the case of btrfs, which will only support blk-crypto-fallback, we should make it just call blk-crypto-fallback directly, so the block devices won't be needed.) Fixes: 22e9947a4b2b ("fscrypt: stop holding extra request_queue references") Cc: stable@vger.kernel.org Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260713023708.9245-1-ebiggers%40kernel.org Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/20260719055602.78828-1-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

fscrypt: Fix key setup in edge case with multiple data unit sizes

2026-07-24T14:11:54+00:00

commit dd015b566d505d698386103e9c80b739c7336eb8 upstream. The addition of support for customizable data unit sizes introduced an edge case where a file's contents can be en/decrypted with the wrong data unit size. It occurs when there are multiple v2 policies that: - Have *different* data unit sizes, via the log2_data_unit_size field - Share the same master_key_identifier, contents_encryption_mode, and either FSCRYPT_POLICY_FLAG_DIRECT_KEY, FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32, or FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 - Are being used on the same filesystem, which also must be mounted with the "inlinecrypt" mount option. Fortunately this edge case doesn't actually occur in practice. I just found it via code review. But it needs to be fixed regardless. The bug is caused by the data unit size not being fully considered when blk_crypto_keys are cached in mk_direct_keys, mk_iv_ino_lblk_32_keys, and mk_iv_ino_lblk_64_keys. They're differentiated only by master key, encryption mode, and flag. However, each one actually has a data unit size too. Only the first data unit size that is cached is used. To fix this, start using the data unit size to differentiate the cached keys. For several reasons, including avoiding increasing the size of struct fscrypt_master_key, just replace all three arrays with a single linked list instead of changing them into two-dimensional arrays. This works well when considering that in practice at most 2 entries are used across all three arrays, so it was already mostly wasted space. For simplicity, make the list also take over the publish/subscribe of the prepared key itself. That is, create separate list nodes for blk_crypto_keys vs crypto_skciphers, and add nodes to the list only when their key is actually prepared. (Note that the legacy fscrypt_direct_keys table in fs/crypto/keysetup_v1.c already works this way.) This eliminates the need for the additional memory barriers when reading and writing the fields of struct fscrypt_prepared_key. Note that I technically should have included the data unit size in the HKDF info string as well. But it's too late to change that. Fixes: 5b1188847180 ("fscrypt: support crypto data unit size less than filesystem block size") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260618180652.52742-1-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

fscrypt: convert bh_get_inode_and_lblk_num to use a folio

2024-05-06T00:53:47+00:00

Patch series "Remove page_mapping()". There are only a few users left. Convert them all to either call folio_mapping() or just use folio->mapping directly. This patch (of 6): Remove uses of page->index, page_mapping() and b_page. Saves a call to compound_head(). Link: https://lkml.kernel.org/r/20240423225552.4113447-1-willy@infradead.org Link: https://lkml.kernel.org/r/20240423225552.4113447-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Eric Biggers Reviewed-by: David Hildenbrand Cc: Sidhartha Kumar Signed-off-by: Andrew Morton

fscrypt: rename fscrypt_info => fscrypt_inode_info

2023-10-09T03:44:26+00:00

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 [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 Signed-off-by: Eric Biggers

fscrypt: support crypto data unit size less than filesystem block size

2023-09-26T05:34:33+00:00

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

fscrypt: compute max_lblk_bits from s_maxbytes and block size

2023-09-26T05:34:30+00:00

For a given filesystem, the number of bits used by the maximum file logical block number is computable from the maximum file size and the block size. These values are always present in struct super_block. Therefore, compute it this way instead of using the value from fscrypt_operations::get_ino_and_lblk_bits. Since filesystems always have to set the super_block fields anyway, this avoids having to provide this information redundantly via fscrypt_operations. This change is in preparation for adding support for sub-block data units. For that, the value that is needed will become "the maximum file data unit index". A hardcoded value won't suffice for that; it will need to be computed anyway. Link: https://lore.kernel.org/r/20230925055451.59499-4-ebiggers@kernel.org Signed-off-by: Eric Biggers

blk-crypto: add a blk_crypto_config_supported_natively helper

2022-11-21T18:39:05+00:00

Add a blk_crypto_config_supported_natively helper that wraps __blk_crypto_cfg_supported to retrieve the crypto_profile from the request queue. With this fscrypt can stop including blk-crypto-profile.h and rely on the public consumer interface in blk-crypto.h. Signed-off-by: Christoph Hellwig Reviewed-by: Eric Biggers Link: https://lore.kernel.org/r/20221114042944.1009870-3-hch@lst.de Signed-off-by: Jens Axboe

blk-crypto: don't use struct request_queue for public interfaces

2022-11-21T18:39:05+00:00

Switch all public blk-crypto interfaces to use struct block_device arguments to specify the device they operate on instead of th request_queue, which is a block layer implementation detail. Signed-off-by: Christoph Hellwig Reviewed-by: Eric Biggers Link: https://lore.kernel.org/r/20221114042944.1009870-2-hch@lst.de Signed-off-by: Jens Axboe

Merge tag 'statx-dioalign-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux

2022-10-04T03:33:41+00:00

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

fscrypt: work on block_devices instead of request_queues

2022-09-22T03:33:06+00:00

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 [ebiggers: bug fixes and minor tweaks] Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220901193208.138056-4-ebiggers@kernel.org