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Commit 0bf3d5c1 authored by Eric Biggers's avatar Eric Biggers Committed by Theodore Ts'o
Browse files

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: 28b4c263 ("ext4 crypto: revalidate dentry after adding or removing the key")
Reported-by: default avatarSarthak Kukreti <sarthakkukreti@chromium.org>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 968dd6d0

fs/dcache.c

+2 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/string.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include <linux/fscrypt.h>

#include <linux/fsnotify.h>

#include <linux/slab.h>

#include <linux/init.h>
@@ -2795,6 +2796,7 @@ static void __d_move(struct dentry *dentry, struct dentry *target, 
	list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);

	__d_rehash(dentry);

	fsnotify_update_flags(dentry);

	fscrypt_handle_d_move(dentry);



	write_seqcount_end(&target->d_seq);

	write_seqcount_end(&dentry->d_seq);

include/linux/fscrypt.h

+16 −0
Original line number Diff line number Diff line
@@ -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)

{