[PATCH] fscrypto: lock inode while setting encryption policy

[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

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

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

[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