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Date: Sun, 17 Mar 2019 13:04:42 -0700 From: Eric Biggers <ebiggers@...nel.org> To: linux-fscrypt@...r.kernel.org Cc: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, linux-mtd@...ts.infradead.org, linux-unionfs@...r.kernel.org, Sarthak Kukreti <sarthakkukreti@...omium.org>, Gao Xiang <gaoxiang25@...wei.com> Subject: [PATCH 3/5] fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory From: Eric Biggers <ebiggers@...gle.com> 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@...omium.org> Signed-off-by: Eric Biggers <ebiggers@...gle.com> --- fs/dcache.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index aac41adf4743..e27d11151d0e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2718,6 +2718,20 @@ static void copy_name(struct dentry *dentry, struct dentry *target) kfree_rcu(old_name, u.head); } +static void fscrypt_update_flags(struct dentry *dentry) +{ +#ifdef CONFIG_FS_ENCRYPTION + /* + * 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(). + */ + dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME; +#endif +} + /* * __d_move - move a dentry * @dentry: entry to move @@ -2795,6 +2809,7 @@ 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_update_flags(dentry); write_seqcount_end(&target->d_seq); write_seqcount_end(&dentry->d_seq); -- 2.21.0
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