fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory
Make __d_move() clear DCACHE_ENCRYPTED_NAME on the source dentry. This
is needed for when d_splice_alias() moves a directory's encrypted alias
to its decrypted alias as a result of the encryption key being added.
Otherwise, the decrypted alias will incorrectly be invalidated on the
next lookup, causing problems such as unmounting a mount the user just
mount()ed there.
Note that we don't have to support arbitrary moves of this flag because
fscrypt doesn't allow dentries with DCACHE_ENCRYPTED_NAME to be the
source or target of a rename().
Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key")
Reported-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 855f743..76c518f 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -89,6 +89,18 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
inode->i_sb->s_cop->dummy_context(inode);
}
+/*
+ * When d_splice_alias() moves a directory's encrypted alias to its decrypted
+ * alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME
+ * must be cleared. Note that we don't have to support arbitrary moves of this
+ * flag because fscrypt doesn't allow encrypted aliases to be the source or
+ * target of a rename().
+ */
+static inline void fscrypt_handle_d_move(struct dentry *dentry)
+{
+ dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
+}
+
/* crypto.c */
extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
extern struct fscrypt_ctx *fscrypt_get_ctx(gfp_t);
@@ -244,6 +256,10 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
return false;
}
+static inline void fscrypt_handle_d_move(struct dentry *dentry)
+{
+}
+
/* crypto.c */
static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
{