Re: [RFC PATCH v3 06/16] ceph: add fscrypt ioctls

[Eric Biggers <ebiggers@kernel.org>]

On Mon, Sep 14, 2020 at 03:16:57PM -0400, Jeff Layton wrote:
> Boilerplate ioctls for controlling encryption.
> 
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/ceph/ioctl.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/fs/ceph/ioctl.c b/fs/ceph/ioctl.c
> index 6e061bf62ad4..381e44b2d60a 100644
> --- a/fs/ceph/ioctl.c
> +++ b/fs/ceph/ioctl.c
> @@ -6,6 +6,7 @@
>  #include "mds_client.h"
>  #include "ioctl.h"
>  #include <linux/ceph/striper.h>
> +#include <linux/fscrypt.h>
>  
>  /*
>   * ioctls
> @@ -289,6 +290,30 @@ long ceph_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  
>  	case CEPH_IOC_SYNCIO:
>  		return ceph_ioctl_syncio(file);
> +
> +	case FS_IOC_SET_ENCRYPTION_POLICY:
> +		return fscrypt_ioctl_set_policy(file, (const void __user *)arg);
> +
> +	case FS_IOC_GET_ENCRYPTION_POLICY:
> +		return fscrypt_ioctl_get_policy(file, (void __user *)arg);
> +
> +	case FS_IOC_GET_ENCRYPTION_POLICY_EX:
> +		return fscrypt_ioctl_get_policy_ex(file, (void __user *)arg);
> +
> +	case FS_IOC_ADD_ENCRYPTION_KEY:
> +		return fscrypt_ioctl_add_key(file, (void __user *)arg);
> +
> +	case FS_IOC_REMOVE_ENCRYPTION_KEY:
> +		return fscrypt_ioctl_remove_key(file, (void __user *)arg);
> +
> +	case FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS:
> +		return fscrypt_ioctl_remove_key_all_users(file, (void __user *)arg);
> +
> +	case FS_IOC_GET_ENCRYPTION_KEY_STATUS:
> +		return fscrypt_ioctl_get_key_status(file, (void __user *)arg);
> +
> +	case FS_IOC_GET_ENCRYPTION_NONCE:
> +		return fscrypt_ioctl_get_nonce(file, (void __user *)arg);

Will you be implementing an encryption feature flag for ceph, similar to what
ext4 and f2fs have?  E.g., ext4 doesn't allow these ioctls unless the filesystem
was formatted with '-O encrypt' (or 'tune2fs -O encrypt' was run later).  There
would be various problems if we didn't do that; for example, old versions of
e2fsck would consider encrypted directories to be corrupted.

- Eric