From: Eric Biggers Date: Wed, 20 Mar 2019 18:39:12 +0000 (-0700) Subject: fscrypt: only set dentry_operations on ciphertext dentries X-Git-Tag: v5.4-rc1~1059^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d456a33f041af4b54f3ce495a86d00c246165032;p=platform%2Fkernel%2Flinux-rpi.git fscrypt: only set dentry_operations on ciphertext dentries Plaintext dentries are always valid, so only set fscrypt_d_ops on ciphertext dentries. Besides marginally improved performance, this allows overlayfs to use an fscrypt-encrypted upperdir, provided that all the following are true: (1) The fscrypt encryption key is placed in the keyring before mounting overlayfs, and remains while the overlayfs is mounted. (2) The overlayfs workdir uses the same encryption policy. (3) No dentries for the ciphertext names of subdirectories have been created in the upperdir or workdir yet. (Since otherwise d_splice_alias() will reuse the old dentry with ->d_op set.) One potential use case is using an ephemeral encryption key to encrypt all files created or changed by a container, so that they can be securely erased ("crypto-shredded") after the container stops. Signed-off-by: Eric Biggers Signed-off-by: Theodore Ts'o --- diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 2e7498a..9d8910e 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -115,9 +115,8 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry) spin_lock(&dentry->d_lock); dentry->d_flags |= DCACHE_ENCRYPTED_NAME; spin_unlock(&dentry->d_lock); + d_set_d_op(dentry, &fscrypt_d_ops); } - - d_set_d_op(dentry, &fscrypt_d_ops); return 0; } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);