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Subject[PATCH 4.4 24/28] fscrypto: lock inode while setting encryption policy
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@google.com>

commit 8906a8223ad4909b391c5628f7991ebceda30e52 upstream.

i_rwsem needs to be acquired while setting an encryption policy so that
concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
serialized (especially the ->get_context() + ->set_context() pair), and
so that new files cannot be created in the directory during or after the
->empty_dir() check.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Richard Weinberger <richard@nod.at>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
fs/ext4/ioctl.c | 4 ++++
fs/f2fs/file.c | 9 ++++++++-
2 files changed, 12 insertions(+), 1 deletion(-)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -633,8 +633,12 @@ resizefs_out:
if (err)
goto encryption_policy_out;

+ mutex_lock(&inode->i_mutex);
+
err = ext4_process_policy(&policy, inode);

+ mutex_unlock(&inode->i_mutex);
+
mnt_drop_write_file(filp);
encryption_policy_out:
return err;
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1535,12 +1535,19 @@ static int f2fs_ioc_set_encryption_polic
#ifdef CONFIG_F2FS_FS_ENCRYPTION
struct f2fs_encryption_policy policy;
struct inode *inode = file_inode(filp);
+ int err;

if (copy_from_user(&policy, (struct f2fs_encryption_policy __user *)arg,
sizeof(policy)))
return -EFAULT;

- return f2fs_process_policy(&policy, inode);
+ mutex_lock(&inode->i_mutex);
+
+ err = f2fs_process_policy(&policy, inode);
+
+ mutex_unlock(&inode->i_mutex);
+
+ return err;
#else
return -EOPNOTSUPP;
#endif

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