[PATCH] fscrypto: lock inode while setting encryption policy

[PATCH] fscrypto: lock inode while setting encryption policy

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

commit 8906a8223ad4909b391c5628f7991ebceda30e52 upstream.  Please apply
to 4.4-stable; it is already in 4.9-stable.  This is a backport of the
fix to fs/ext4/ and fs/f2fs/ for old kernels.

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

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 1fb12f9c97a6..789e2d6724a9 100644
--- 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;
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index a197215ad52b..4b449d263333 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1535,12 +1535,19 @@ static int f2fs_ioc_set_encryption_policy(struct file *filp, unsigned long arg)
 #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
-- 
2.12.0.367.g23dc2f6d3c-goog

Re: [PATCH] fscrypto: lock inode while setting encryption policy

[Greg Kroah-Hartman]

On Thu, Mar 16, 2017 at 03:22:29PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> commit 8906a8223ad4909b391c5628f7991ebceda30e52 upstream.  Please apply
> to 4.4-stable; it is already in 4.9-stable.  This is a backport of the
> fix to fs/ext4/ and fs/f2fs/ for old kernels.

Thanks, now applied.

greg k-h

Re: [PATCH] fscrypto: lock inode while setting encryption policy

[Theodore Ts'o]

On Thu, Sep 29, 2016 at 07:20:20PM +0200, Richard Weinberger wrote:
> On 28.09.2016 20:34, Eric Biggers wrote:
> > 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>
> 
> Reviewed-by: Richard Weinberger <richard@nod.at>

Thanks, applied.

					- Ted

Re: [PATCH] fscrypto: lock inode while setting encryption policy

[Eric Biggers]

On Thu, Sep 29, 2016 at 07:20:20PM +0200, Richard Weinberger wrote:
> On 28.09.2016 20:34, Eric Biggers wrote:
> > 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>
> 
> Reviewed-by: Richard Weinberger <richard@nod.at>
> 
> Thanks,
> //richard

Thanks.  Does anyone else have comments on this patch?  It hasn't been applied
yet.

Eric

Re: [PATCH] fscrypto: lock inode while setting encryption policy

[Eric Biggers]

On Thu, Sep 29, 2016 at 07:20:20PM +0200, Richard Weinberger wrote:
> On 28.09.2016 20:34, Eric Biggers wrote:
> > 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>
> 
> Reviewed-by: Richard Weinberger <richard@nod.at>
> 
> Thanks,
> //richard

Thanks.  Does anyone else have comments on this patch?  It hasn't been applied
yet.

Eric

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Re: [PATCH] fscrypto: lock inode while setting encryption policy

[Richard Weinberger]

On 28.09.2016 20:34, Eric Biggers wrote:
> 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>

Reviewed-by: Richard Weinberger <richard@nod.at>

Thanks,
//richard

[PATCH] fscrypto: lock inode while setting encryption policy

[Eric Biggers]

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>

---
Note: to be applied without conflict, this patch needs the changes from
v4.8-rc6.

---
 fs/crypto/policy.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index ed115ac..6865663 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -109,6 +109,8 @@ int fscrypt_process_policy(struct file *filp,
 	if (ret)
 		return ret;
 
+	inode_lock(inode);
+
 	if (!inode_has_encryption_context(inode)) {
 		if (!S_ISDIR(inode->i_mode))
 			ret = -EINVAL;
@@ -127,6 +129,8 @@ int fscrypt_process_policy(struct file *filp,
 		ret = -EINVAL;
 	}
 
+	inode_unlock(inode);
+
 	mnt_drop_write_file(filp);
 	return ret;
 }
-- 
2.8.0.rc3.226.g39d4020