Ext4 and F2FS currently both support casefolding and encryption, but not at the same time. These patches aim to rectify that. Since directory names are stored case preserved, we cannot just take the hash of the ciphertext. Instead we use the siphash of the casefolded name. With this we no longer have a direct path from an encrypted name to the hash without the key. To deal with this, fscrypt now always includes the hash in the name it presents when the key is not present. There is a pre-existing bug where you can change parts of the hash and still match the name so long as the disruption to the hash does not happen to affect lookup on that filesystem. I'm not sure how to fix that without making ext4 lookups slower in the more common case. I moved the identical dcache operations for ext4 and f2fs into the VFS, as any filesystem that uses casefolding will need the same code. This will also allow further optimizations to that path, although my current changes don't take advantage of that yet. For Ext4, this also means that we need to store the hash on disk. We only do so for encrypted and casefolded directories to avoid on disk format changes. Previously encryption and casefolding could not live on the same filesystem, and we're relaxing that requirement. F2fs is a bit more straightforward since it already stores hashes on disk. I've updated the related tools with just enough to enable the feature. I still need to adjust their respective fsck's, although without access to the keys, they won't be able to verify the hashes of casefolded and encrypted names. Daniel Rosenberg (8): fscrypt: Add siphash and hash key for policy v2 fscrypt: Don't allow v1 policies with casefolding fscrypt: Change format of no-key token vfs: Fold casefolding into vfs f2fs: Handle casefolding with Encryption ext4: Use struct super_blocks' casefold data ext4: Hande casefolding with encryption ext4: Optimize match for casefolded encrypted dirs Documentation/filesystems/ext4/directory.rst | 27 ++ fs/crypto/Kconfig | 1 + fs/crypto/fname.c | 204 +++++++++--- fs/crypto/fscrypt_private.h | 9 + fs/crypto/keysetup.c | 29 +- fs/crypto/policy.c | 26 +- fs/dcache.c | 35 ++ fs/ext4/dir.c | 72 +---- fs/ext4/ext4.h | 87 +++-- fs/ext4/hash.c | 26 +- fs/ext4/ialloc.c | 5 +- fs/ext4/inline.c | 41 +-- fs/ext4/namei.c | 318 ++++++++++++------- fs/ext4/super.c | 21 +- fs/f2fs/dir.c | 115 +++---- fs/f2fs/f2fs.h | 14 +- fs/f2fs/hash.c | 25 +- fs/f2fs/inline.c | 9 +- fs/f2fs/super.c | 17 +- fs/f2fs/sysfs.c | 8 +- fs/inode.c | 8 + fs/namei.c | 43 ++- include/linux/fs.h | 12 + include/linux/fscrypt.h | 107 +++---- 24 files changed, 797 insertions(+), 462 deletions(-) -- 2.24.0.393.g34dc348eaf-goog
