From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org,
Sarthak Kukreti <sarthakkukreti@chromium.org>,
Gao Xiang <gaoxiang25@huawei.com>
Subject: [PATCH 3/5] fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory
Date: Sun, 17 Mar 2019 13:04:42 -0700 [thread overview]
Message-ID: <20190317200444.5967-4-ebiggers@kernel.org> (raw)
In-Reply-To: <20190317200444.5967-1-ebiggers@kernel.org>
From: Eric Biggers <ebiggers@google.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@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.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
next prev parent reply other threads:[~2019-03-17 20:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-17 20:04 [PATCH 0/5] fscrypt: d_revalidate fixes and cleanups Eric Biggers
2019-03-17 20:04 ` [PATCH 1/5] fscrypt: clean up and improve dentry revalidation Eric Biggers
2019-03-17 20:38 ` Al Viro
2019-03-18 20:29 ` Eric Biggers
2019-03-18 21:25 ` Al Viro
2019-03-17 20:04 ` [PATCH 2/5] fscrypt: fix race allowing rename() and link() of ciphertext dentries Eric Biggers
2019-03-17 20:04 ` Eric Biggers [this message]
2019-03-17 20:04 ` [PATCH 4/5] fscrypt: only set dentry_operations on " Eric Biggers
2019-03-17 20:04 ` [PATCH 5/5] fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext Eric Biggers
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