From 0bf3d5c1604ecbbd4e49e9f5b3c79152b87adb0d Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Wed, 20 Mar 2019 11:39:11 -0700
Subject: [PATCH] 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>
---
fs/dcache.c | 2 ++
include/linux/fscrypt.h | 16 ++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/fs/dcache.c b/fs/dcache.c
index aac41adf47433..647e6ed426e20 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -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);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 855f743c226e6..76c518f1e4c7a 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)
{
--
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