Re: [PATCH 3/3] ceph: add support for encrypted snapshot names

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2022-03-04 at 16:14 +0000, Luís Henriques wrote:
> Since filenames in encrypted directories are already encrypted and shown
> as a base64-encoded string when the directory is locked, snapshot names
> should show a similar behaviour.
> 
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
>  fs/ceph/dir.c   |  9 +++++++++
>  fs/ceph/inode.c | 13 +++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 934402f5e9e6..17d2f18a1fd1 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -1069,6 +1069,15 @@ static int ceph_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
>  		op = CEPH_MDS_OP_MKSNAP;
>  		dout("mksnap dir %p snap '%pd' dn %p\n", dir,
>  		     dentry, dentry);
> +		/*
> +		 * Encrypted snapshots require d_revalidate to force a
> +		 * LOOKUPSNAP to cleanup dcache
> +		 */
> +		if (IS_ENCRYPTED(dir)) {
> +			spin_lock(&dentry->d_lock);
> +			dentry->d_flags |= DCACHE_NOKEY_NAME;
> +			spin_unlock(&dentry->d_lock);
> +		}
>  	} else if (ceph_snap(dir) == CEPH_NOSNAP) {
>  		dout("mkdir dir %p dn %p mode 0%ho\n", dir, dentry, mode);
>  		op = CEPH_MDS_OP_MKDIR;
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index 8b0832271fdf..357335a11384 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -182,6 +182,19 @@ struct inode *ceph_get_snapdir(struct inode *parent)
>  	ci->i_rbytes = 0;
>  	ci->i_btime = ceph_inode(parent)->i_btime;
>  
> +	/* if encrypted, just borrow fscrypt_auth from parent */
> +	if (IS_ENCRYPTED(parent)) {
> +		struct ceph_inode_info *pci = ceph_inode(parent);
> +
> +		ci->fscrypt_auth = kmemdup(pci->fscrypt_auth,
> +					   pci->fscrypt_auth_len,
> +					   GFP_KERNEL);
> +		if (ci->fscrypt_auth) {
> +			inode->i_flags |= S_ENCRYPTED;
> +			ci->fscrypt_auth_len = pci->fscrypt_auth_len;
> +		} else
> +			dout("Failed to alloc memory for fscrypt_auth in snapdir\n");

Should we return an error in this case?

> +	}
>  	if (inode->i_state & I_NEW) {
>  		inode->i_op = &ceph_snapdir_iops;
>  		inode->i_fop = &ceph_snapdir_fops;

Seems simple and straightforward at first glance.
-- 
Jeff Layton <jlayton@kernel.org>