Patch "fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory" has been added to the 4.19-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fs-fscrypt-clear-dcache_encrypted_name-when-unaliasing-directory.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Sun Nov  1 11:35:18 AM CET 2020
From: Eric Biggers <ebiggers at kernel.org>
Date: Sat, 31 Oct 2020 15:05:51 -0700
Subject: fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory
To: stable at vger.kernel.org
Cc: linux-fscrypt at vger.kernel.org, linux-ext4 at vger.kernel.org, linux-f2fs-devel at lists.sourceforge.net, linux-mtd at lists.infradead.org, Sarthak Kukreti <sarthakkukreti at chromium.org>, Theodore Ts'o <tytso at mit.edu>
Message-ID: <20201031220553.1085782-4-ebiggers at kernel.org>

From: Eric Biggers <ebiggers at google.com>

commit 0bf3d5c1604ecbbd4e49e9f5b3c79152b87adb0d upstream.

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 at chromium.org>
Signed-off-by: Eric Biggers <ebiggers at google.com>
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 fs/dcache.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2713,6 +2713,20 @@ static void copy_name(struct dentry *den
 }
 
 /*
+ * 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)
+{
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+	dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
+#endif
+}
+
+/*
  * __d_move - move a dentry
  * @dentry: entry to move
  * @target: new dentry
@@ -2787,6 +2801,7 @@ static void __d_move(struct dentry *dent
 	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);


Patches currently in stable-queue which might be from ebiggers at kernel.org are

queue-4.19/fscrypt-only-set-dentry_operations-on-ciphertext-dentries.patch
queue-4.19/fscrypt-clean-up-and-improve-dentry-revalidation.patch
queue-4.19/fscrypt-fix-race-allowing-rename-and-link-of-ciphertext-dentries.patch
queue-4.19/fs-fscrypt-clear-dcache_encrypted_name-when-unaliasing-directory.patch
queue-4.19/fscrypt-fix-race-where-lookup-marks-plaintext-dentry-as-ciphertext.patch